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Neurologic complications after the frozen elephant trunk procedure: A meta-analysis of more than 3000 patients

Open AccessPublished:October 17, 2019DOI:https://doi.org/10.1016/j.jtcvs.2019.10.031

      Abstract

      Objective

      The frozen elephant trunk technique's safety regarding spinal cord ischemia has been questioned. We used a meta-analysis to determine the rates of adverse neurologic events and mortality.

      Methods

      We searched PubMed/Medline, Embase, Scopus, and Cochrane databases (inception to April 2018) to identify studies of neurologic events after the frozen elephant trunk procedure. Separate meta-analyses were conducted with random-effects models to assess frozen elephant trunk associations with spinal cord ischemia, stroke, operative mortality, and all adverse events combined. Subgroup analyses compared outcomes in patients with acute versus nonacute type A dissection and aneurysm and with different extents of coverage.

      Results

      Thirty-five studies (total N = 3154) met inclusion criteria. The pooled rates of the outcomes of interest were 4.7% (95% confidence interval, 3.5-6.2) for spinal cord ischemia, 7.6% (95% confidence interval, 5.0-11.5) for stroke, and 8.8% (95% confidence interval, 7.0-10.9) for operative mortality. The spinal cord ischemia event rate was higher with stent length 15 cm or greater or coverage to T8 or beyond than with stent length of 10 cm (11.6% vs 2.5%, P < .001). Adverse event rates in patients with acute type A aortic dissection versus nonacute dissection or aneurysm were as follows: mortality 9.2% versus 7.6% (P = .46), stroke 9.3% versus 6.6% (P = .51), and overall adverse events 22.0% versus 16.5% (P = .41).

      Conclusions

      As the frozen elephant trunk procedure becomes more popular, accurate data regarding outcomes are vital. We associated the frozen elephant trunk technique with (nonsignificantly) more adverse events overall in acute type A dissection cases. Stent length of 10 cm was associated with significantly less risk of spinal cord ischemia. Using a stent 15 cm or greater or coverage extending to T8 or farther should be avoided.

      Graphical abstract

      Key Words

      Abbreviations and Acronyms:

      CI (confidence interval), ET (elephant trunk), FET (frozen elephant trunk), SCI (spinal cord ischemia)
      Figure thumbnail fx2
      Visual summary of our meta-analysis of 35 FET studies, with results and subgroup analyses.
      In FET, 10-cm stent length is advisable; length 15 cm or greater or coverage to or beyond T8 should be avoided to prevent SCI. FET should be used cautiously for acute type A aortic dissection.
      This meta-analysis of 35 observational studies examines mortality and neurologic outcomes associated with the FET technique in patients who require total arch replacement. Currently, the results represent the best available evidence regarding the outcomes of FET in such patients. Judicious use of the technique is advisable.
      See Commentaries on pages 34 and 35.
      Traditionally, the elephant trunk (ET) procedure involves 2 stages, and the likelihood of death before the second stage is high.
      • Castrovinci S.
      • Murana G.
      • de Maat G.E.
      • Smith T.
      • Schepens M.A.
      • Heijmen R.H.
      • et al.
      The classic elephant trunk technique for staged thoracic and thoracoabdominal aortic repair: long-term results.
      • Crawford E.S.
      • Coselli J.S.
      • Svensson L.G.
      • Safi H.J.
      • Hess K.R.
      Diffuse aneurysmal disease (chronic aortic dissection, Marfan, and mega aorta syndromes) and multiple aneurysm. Treatment by subtotal and total aortic replacement emphasizing the elephant trunk operation.
      • Etz C.D.
      • Plestis K.A.
      • Kari F.A.
      • Luehr M.
      • Bodian C.A.
      • Spielvogel D.
      • et al.
      Staged repair of thoracic and thoracoabdominal aortic aneurysms using the elephant trunk technique: a consecutive series of 215 first stage and 120 complete repairs.
      • Ius F.
      • Hagl C.
      • Haverich A.
      • Pichlmaier M.
      Elephant trunk procedure 27 years after Borst: what remains and what is new?.
      • Safi H.J.
      • Miller 3rd, C.C.
      • Estrera A.L.
      • Huynh T.T.
      • Rubenstein F.S.
      • Subramaniam M.H.
      • et al.
      Staged repair of extensive aortic aneurysms: morbidity and mortality in the elephant trunk technique.
      • Svensson L.G.
      • Rushing G.D.
      • Valenzuela E.S.
      • Rafael A.E.
      • Batizy L.H.
      • Blackstone E.H.
      • et al.
      Modifications, classification, and outcomes of elephant-trunk procedures.
      The frozen elephant trunk (FET) procedure is a newer approach designed to treat extensive pathology of the thoracic aorta in a single stage or by facilitating the second stage of a 2-stage procedure.
      • Preventza O.
      • Al-Najjar R.
      • LeMaire S.A.
      • Weldon S.
      • Coselli J.S.
      Total arch replacement with frozen elephant trunk technique.
      Single-center institutional experiences and small series comprise most of the existing reports.
      • Shrestha M.
      • Bachet J.
      • Bavaria J.
      • Carrel T.P.
      • De Paulis R.
      • Di Bartolomeo R.
      • et al.
      Current status and recommendations for use of the frozen elephant trunk technique: a position paper by the Vascular Domain of EACTS.
      Figure thumbnail fx3
      Video 1Summary of meta-analysis study of more than 3000 patients in whom the FET technique was used and a discussion of this technique's importance. Video available at: https://www.jtcvs.org/article/S0022-5223(19)32242-1/fulltext.

      Patients and Methods

      Search Strategy

      Four databases (EMBASE, PubMed/Medline, Scopus, and Cochrane Library) were searched from their beginning to April 2018 to identify studies of the potential association between the FET approach and new postoperative neurologic symptoms (permanent or transient). The search terms used are listed in Table 1. Only English-language articles were searched. The references of all articles included in the study were examined for further relevant series.
      Table 1Search terms used to identify articles for review
      DatabaseSearch terms
      PubMed/MedlineMedical Subject Heading (MeSH) terms, search filter [tiab] (title/abstract) and other terms (ot) as follows:

      “Aortic Aneurysm, Thoracic” [Mesh:NoExp] OR “Aortic Aneurysm, Thoracic/surgery” [Mesh:NoExp] OR “Aorta, Thoracic/surgery” [Mesh] OR “Aneurysm, Dissecting” [Majr:NoExp] OR “Aneurysm, Dissecting/surgery” [Majr:NoExp] OR “elephant trunk” [tiab] OR “elephant trunk” OR “elephant trunk” [ot] AND (“Treatment Outcome” [Mesh] OR “Postoperative Complications” [Mesh] OR “Morbidity” [Mesh] OR “morbidity” [tiab] OR risk*[tiab] OR “patient outcome” [tiab] OR “stroke” [tiab] OR “CVA” [tiab] OR “cerebral vascular accident” [tiab] OR “spinal cord injury” [tiab] OR “Treatment Outcome” [tiab] OR “paraplegia” [tiab] OR “paraparesis” [tiab] OR “neurologic* complications” [tiab] OR “spinal cord ischemia” [tiab] NOT ((Animals NOT Humans)) AND ((randomized controlled trial [pt] OR controlled clinical trial [pt] OR randomized [tiab] OR placebo [tiab] OR clinical trials as topic [mesh:noexp] OR randomly [tiab] OR trial [ti] NOT (animals [mh] NOT humans)))
      Scopus(TITLE-ABS-KEY ((Stroke OR “cerebral vascular accident” OR “CVA” OR “spinal cord injury” OR “spinal cord ischemia” OR “paraplegia” OR “paraparesis” OR (neurologic* AND complication*)))) AND (TITLE-ABS-KEY (“elephant trunk” OR (elephant AND trunk))) AND (LIMIT-TO (LANGUAGE, “English”))
      Embase‘cerebrovascular accident’/exp OR ‘spinal cord injury’/exp OR ‘spinal cord ischemia’/exp OR ‘paraplegia’/exp OR ‘neurological complication’/exp OR ‘stroke’ OR ‘CVA’ OR ‘cerebral vascular accident’ OR ‘spinal cord injury’ OR paraplegia OR paraparesis OR ‘neurologic* complications’ OR (neurologic* AND complication*) OR ‘spinal cord ischemia’ ‘elephant trunk technique’/exp OR ‘elephant trunk procedure’/exp OR (elephant AND trunk) OR ‘elephant trunk’:ab,ti OR ‘elephant trunk’ AND [english]
      Cochrane Library“elephant trunk”

      Study Design and Eligibility Criteria

      A study was deemed eligible if it described aortic arch procedures performed by the ET technique, either “frozen” or “stented.” The definition of FET included a total arch operation. Proximal arch or hemiarch procedures (ie, procedures that did not involve the entire arch) with antegrade or retrograde stent delivery in the descending thoracic aorta were excluded from this analysis. Other inclusion criteria included a description of intrathoracic aortic arch repair performed via median sternotomy, the baseline characteristics of the patients, and the incidence of permanent or transient SCI, mortality, or permanent or transient stroke, as well as a sample size of 10 or more patients to prevent bias arising from small samples (Figure 1).
      Figure thumbnail gr1
      Figure 1Flow chart showing selection and screening process for articles considered for inclusion in the meta-analysis. FET, Frozen elephant trunk.
      When multiple publications by the same authors were identified and study cohorts overlapped, only the latest report was included. Other meta-analysis studies were excluded, as were reports that describe only surgical techniques. Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines were used.
      • Moher D.
      • Shamseer L.
      • Clarke M.
      • Ghersi D.
      • Liberati A.
      • Petticrew M.
      • et al.
      Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement.
      The abstracts of all articles were independently assessed by 2 reviewers (O.P. and J.S.C.); if the abstract suggested that the study met the inclusion criteria for our analysis, the full-text article was retrieved. Available data were analyzed, and if the 2 reviewers made different decisions about whether a given article should be included, a consensus was reached by reexamining the articles with regard to the exclusion and inclusion criteria and the specific techniques described. Data were extracted from abstracts, figures, and tables and entered into Microsoft Excel (Microsoft Corp, Redmond, Wash). In addition, attempts were made to contact the individual authors for any necessary clarifications.

      Statistical Analysis

      Standard descriptive statistics using meta-analysis software, which allowed us to account for the differing weights of the studies, were used to summarize the demographic, preoperative, intraoperative, and outcome data of the eligible studies. Data are presented as number and percentage or mean with 95% confidence interval (CI), as appropriate. The primary end points of the meta-analysis were stroke, SCI (reported as paralysis, paraplegia, or paraparesis), and operative mortality (within 30 days of surgery or before hospital discharge). The pooled effect estimates were calculated as the weighted mean by using a random-effects model (DerSimonian-Laird), which incorporates between-trial heterogeneity and gives wider and more conservative CIs when heterogeneity is present.
      • DerSimonian R.
      • Laird N.
      Meta-analysis in clinical trials.
      The analyses were performed after a logit transformation of the data, and the results were expressed as an event rate (%) with a 95% CI.
      Two subgroup analyses were performed, using the Z-test to obtain the P value comparing the 2 groups. The first one compared outcomes from studies that included only patients with acute type A aortic dissection versus studies that included only patients with nonacute type A dissection and aneurysm to determine whether FET operations yielded different results in these 2 patient populations. The second subgroup analysis compared the results from studies that used only a longer stent (≥15 cm or spinal cord coverage to T8 or farther) versus those that used only a shorter (10-cm) stent.
      The I2 statistic, defined as the percentage of total variability across studies attributable to heterogeneity rather than chance, was used to assess statistical heterogeneity. The I2 value lies between 0% and 100%, and is presented with a 95% CI. We used published guidelines to classify the heterogeneity as low (I2 = 25% to 49%), moderate (I2 = 50% to 74%), or high (I2 > 75%).
      • Higgins J.P.
      • Thompson S.G.
      • Deeks J.J.
      • Altman D.G.
      Measuring inconsistency in meta-analyses.
      ,
      • Borenstein M.
      • Higgins J.P.
      • Hedges L.V.
      • Rothstein H.R.
      Basics of meta-analysis: I2 is not an absolute measure of heterogeneity.
      In addition, the prediction interval was calculated to determine the range in which the true effect size would fall in 95% of all populations. The possibility of publication bias was evaluated quantitatively with the Egger test and assessed qualitatively with funnel plots. The funnel plots were constructed by Duval and Tweedie's “trim and fill” method, which offers a more nuanced perspective and estimates how the effect size would shift if the apparent bias were to be removed by imputing the missing studies. All statistical analyses were conducted with Comprehensive Meta-Analysis statistical software (version 3, Biostat Inc, Englewood, NJ).

      Results

      Study Selection and Characteristics of the Trials

      The search yielded 745 articles; 390 were excluded as duplicate or overlapping publications, and 355 were deemed potentially relevant. Another 320 articles were excluded after exclusion criteria were applied (Figure 1). Thus, our analysis included 34 publications that met the criteria for full review (Table 2).
      • Usui A.
      • Fujimoto K.
      • Ishiguchi T.
      • Yoshikawa M.
      • Akita T.
      • Ueda Y.
      Cerebrospinal dysfunction after endovascular stent-grafting via a median sternotomy: the frozen elephant trunk procedure.
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      • Shimamura K.
      • Kuratani T.
      • Matsumiya G.
      • Kato M.
      • Shirakawa Y.
      • Takano H.
      • et al.
      Long-term results of the open stent-grafting technique for extended aortic arch disease.
      • Li B.
      • Sun L.
      • Chang Q.
      • Zhu J.
      • Yu C.
      • Liu Y.
      • et al.
      Total arch replacement with stented elephant trunk technique: a proposed treatment for complicated Stanford type B aortic dissection.
      • Chen X.
      • Huang F.
      • Xu M.
      • Wang L.
      • Jiang Y.
      • Xiao L.
      • et al.
      The stented elephant trunk procedure combined total arch replacement for DeBakey I aortic dissection: operative result and follow-up.
      • Sun L.
      • Zhao X.
      • Chang Q.
      • Zhu J.
      • Liu Y.
      • Yu C.
      • et al.
      Repair of chronic type B dissection with aortic arch involvement using a stented elephant trunk procedure.
      • Lima B.
      • Roselli E.E.
      • Soltesz E.G.
      • Johnston D.R.
      • Pujara A.C.
      • Idrees J.
      • et al.
      Modified and “reverse” frozen elephant trunk repairs for extensive disease and complications after stent grafting.
      • Shen K.
      • Tang H.
      • Jing R.
      • Liu F.
      • Zhou X.
      Application of triple-branched stent graft for Stanford type A aortic dissection: potential risks.
      • Zhao H.P.
      • Zhu J.M.
      • Ma W.G.
      • Zheng J.
      • Liu Y.M.
      • Sun L.Z.
      Total arch replacement with stented elephant trunk technique for acute type B aortic dissection involving the aortic arch.
      • Hoffman A.
      • Damberg A.L.M.
      • Schalte G.
      • Mahnken A.H.
      • Raweh A.
      • Autschbach R.
      Thoracic stent graft sizing for frozen elephant trunk repair in acute type A dissection.
      • Di Marco L.
      • Pacini D.
      • Leone A.
      • Pantaleo A.
      • Cefarelli M.
      • Di Eusanio M.
      The Thoraflex hybrid frozen elephant trunk device: the Bologna experience.
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      • Nakamura K.
      • Nagahama H.
      • Nakamura E.
      • Yano M.
      • Matsuyama M.
      • Nishimura M.
      • et al.
      Predictors of early and late outcome after total arch replacement for atherosclerotic aortic arch aneurysm.
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      • Xiao Z.
      • Meng W.
      • Zhu D.
      • Guo Y.
      • Zhang E.
      Treatment strategies for left subclavian artery during total arch replacement combined with stented elephant trunk implantation.
      • Yang S.M.
      • Xu P.
      • Li C.X.
      • Huang Q.
      • Gao H.B.
      • Li Z.F.
      • et al.
      A modified total arch replacement combined with a stented elephant trunk implantation for acute type A dissection under deep hypothermic circulatory arrest and selective antegrade cerebral perfusion.
      • Zhang H.
      • Lang X.
      • Lu F.
      • Song Z.
      • Wang J.
      • Han L.
      • et al.
      Acute type A dissection without intimal tear in arch: proximal or extensive repair?.
      • Dias R.R.
      • Duncan J.A.
      • Vianna D.S.
      • de Faria L.B.
      • Fernandes F.
      • Ramirez F.J.
      • et al.
      Surgical treatment of complex aneurysms and thoracic aortic dissections with the Frozen Elephant Trunk technique.
      • Hiraoka A.
      • Chikazawa G.
      • Tamura K.
      • Totsugawa T.
      • Sakaguchi T.
      • Yoshitaka H.
      Clinical outcomes of different approaches to aortic arch disease.
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      • El-Sayed Ahmad A.
      • Risteski P.
      • Papadopoulos N.
      • Radwan M.
      • Moritz A.
      • Zierer A.
      Minimally invasive approach for aortic arch surgery employing the frozen elephant trunk technique.
      • Gong M.
      • Ma W.G.
      • Guan X.L.
      • Wang L.F.
      • Li J.C.
      • Lan F.
      • et al.
      Moderate hypothermic circulatory arrest in total arch repair for acute type A aortic dissection: clinical safety and efficacy.
      • Leontyev S.
      • Tsagakis K.
      • Pacini D.
      • Di Bartolomeo R.
      • Mohr F.W.
      • Weiss G.
      • et al.
      Impact of clinical factors and surgical techniques on early outcome of patients treated with frozen elephant trunk technique by using EVITA open stent-graft: results of a multicentre study.
      • Ma M.
      • Liu L.
      • Feng X.
      • Wang Y.
      • Hu M.
      • Pan T.
      • et al.
      Moderate hypothermic circulatory arrest with antegrade cerebral perfusion for rapid total arch replacement in acute type A aortic dissection.
      • Shrestha M.
      • Kaufeld T.
      • Beckmann E.
      • Fleissner F.
      • Umminger J.
      • Abd Alhadi F.
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: single-center results of the first 100 patients.
      • Aalaei-Andabili S.H.
      • Scali S.
      • Klodell C.
      • Lee T.
      • Hess P.
      • Martin T.
      • et al.
      Outcomes of antegrade stent graft deployment during hybrid aortic arch repair.
      • Chen L.
      • Qi R.D.
      • Liu W.
      • Li C.N.
      • Zhang N.
      • Zhu J.M.
      • et al.
      Repair of complicated chronic type B dissection with distal aortic arch involvement using left subclavian artery transposition with implantation of a stented elephant trunk.
      • Hu X.
      • Wang Z.
      • Ren Z.
      • Hu R.
      • Wu H.
      Simplified total aortic arch replacement with an in situ stent graft fenestration technique for acute type A aortic dissection.
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      • Koizumi S.
      • Nagasawa A.
      • Koyama T.
      Total aortic arch replacement using frozen elephant trunk technique with J Graft Open Stent Graft for distal aortic arch aneurysm.
      • Kreibich M.
      • Berger T.
      • Morlock J.
      • Kondov S.
      • Scheumann J.
      • Kari F.A.
      • et al.
      The frozen elephant trunk technique for the treatment of acute complicated type B aortic dissection.
      • Ma M.
      • Feng X.
      • Wang J.
      • Dong Y.
      • Chen T.
      • Liu L.
      • et al.
      Acute type I aortic dissection: a propensity-matched comparison of elephant trunk and arch debranching repairs.
      • Roselli E.E.
      • Idrees J.J.
      • Bakaeen F.G.
      • Tong M.Z.
      • Soltesz E.G.
      • Mick S.
      • et al.
      Evolution of simplified frozen elephant trunk repair for acute DeBakey type I dissection: midterm outcomes.
      One of these publications
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      reported on 2 separate cohorts, so we treated it as 2 studies for the purpose of our analyses. Thus, our effective sample size was 35 studies.
      Table 2Study characteristics
      First author (year)Study periodNCountryInstitution
      Usui (2002)
      • Usui A.
      • Fujimoto K.
      • Ishiguchi T.
      • Yoshikawa M.
      • Akita T.
      • Ueda Y.
      Cerebrospinal dysfunction after endovascular stent-grafting via a median sternotomy: the frozen elephant trunk procedure.
      1997-200224JapanNagoya University Graduate School of Medicine, Aichi Medical University
      Flores (2006)
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      1996-200425JapanHokkaido University Graduate School of Medicine
      Shimamura (2008)
      • Shimamura K.
      • Kuratani T.
      • Matsumiya G.
      • Kato M.
      • Shirakawa Y.
      • Takano H.
      • et al.
      Long-term results of the open stent-grafting technique for extended aortic arch disease.
      1994-2004126JapanOsaka University Graduate School of Medicine, Osaka General Medical Center, Morinomiya Hospital
      Li (2009)
      • Li B.
      • Sun L.
      • Chang Q.
      • Zhu J.
      • Yu C.
      • Liu Y.
      • et al.
      Total arch replacement with stented elephant trunk technique: a proposed treatment for complicated Stanford type B aortic dissection.
      2003-200831ChinaCardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College
      Chen (2010)
      • Chen X.
      • Huang F.
      • Xu M.
      • Wang L.
      • Jiang Y.
      • Xiao L.
      • et al.
      The stented elephant trunk procedure combined total arch replacement for DeBakey I aortic dissection: operative result and follow-up.
      2004-200928ChinaNanjing Cardiovascular Disease Research Institute, Nainjing First Hospital Affiliated to Nanjing Medical University
      Sun (2010)
      • Sun L.
      • Zhao X.
      • Chang Q.
      • Zhu J.
      • Liu Y.
      • Yu C.
      • et al.
      Repair of chronic type B dissection with aortic arch involvement using a stented elephant trunk procedure.
      2003-200819ChinaCardiovascular Institute and Fu Wai Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Tianjin Cardiovascular Institute and Tianjin Chest Hospital
      Lima (2012)
      • Lima B.
      • Roselli E.E.
      • Soltesz E.G.
      • Johnston D.R.
      • Pujara A.C.
      • Idrees J.
      • et al.
      Modified and “reverse” frozen elephant trunk repairs for extensive disease and complications after stent grafting.
      2001-201031United StatesHeart and Vascular Institute, Cleveland Clinic
      Shen (2012)
      • Shen K.
      • Tang H.
      • Jing R.
      • Liu F.
      • Zhou X.
      Application of triple-branched stent graft for Stanford type A aortic dissection: potential risks.
      201038ChinaThe Second Xiangya Hospital, Central South University
      Zhao (2012)
      • Zhao H.P.
      • Zhu J.M.
      • Ma W.G.
      • Zheng J.
      • Liu Y.M.
      • Sun L.Z.
      Total arch replacement with stented elephant trunk technique for acute type B aortic dissection involving the aortic arch.
      2006-201124ChinaBeijing Aortic Disease Center; Beijing Institute of Heart, Lung and Blood Vessel Diseases; Beijing Anzhen Hospital, Capital Medical University
      Hoffman (2013)
      • Hoffman A.
      • Damberg A.L.M.
      • Schalte G.
      • Mahnken A.H.
      • Raweh A.
      • Autschbach R.
      Thoracic stent graft sizing for frozen elephant trunk repair in acute type A dissection.
      2009-201132GermanyUniversity Hospital RWTH Aachen
      Di Marco (2014)
      • Di Marco L.
      • Pacini D.
      • Leone A.
      • Pantaleo A.
      • Cefarelli M.
      • Di Eusanio M.
      The Thoraflex hybrid frozen elephant trunk device: the Bologna experience.
      2013-201411ItalyS. Orsola-Malpighi Hospital, University of Bologna
      Ma (2014)
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      2003-2012456ChinaChinese multicenter
      Institutions included Beijing Aortic Disease Center, Beijing Anzhen Hospital of Capital Medical University, Beijing Institute of Heart, Lung and Blood Vessel Diseases, and Beijing Engineering Research Center of Vascular Prostheses; Fu Wai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Disease; and Aortic Institute at Yale-New Haven.
      Ma (2014B)
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      2003-2012347ChinaChinese multicenter
      Institutions included Beijing Aortic Disease Center, Beijing Anzhen Hospital of Capital Medical University, Beijing Institute of Heart, Lung and Blood Vessel Diseases, and Beijing Engineering Research Center of Vascular Prostheses; Fu Wai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Disease; and Aortic Institute at Yale-New Haven.
      Nakamura (2014)
      • Nakamura K.
      • Nagahama H.
      • Nakamura E.
      • Yano M.
      • Matsuyama M.
      • Nishimura M.
      • et al.
      Predictors of early and late outcome after total arch replacement for atherosclerotic aortic arch aneurysm.
      1998-201051JapanUniversity of Miyazaki, Miyazaki Prefectural Nobeoka Hospital
      Shi (2014)
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      2006-201184ChinaFirst Affiliated Hospital, China Medical University
      Xiao (2014)
      • Xiao Z.
      • Meng W.
      • Zhu D.
      • Guo Y.
      • Zhang E.
      Treatment strategies for left subclavian artery during total arch replacement combined with stented elephant trunk implantation.
      2008-201133ChinaWest China Hospital, Sichuan University Chengdu
      Yang (2014)
      • Yang S.M.
      • Xu P.
      • Li C.X.
      • Huang Q.
      • Gao H.B.
      • Li Z.F.
      • et al.
      A modified total arch replacement combined with a stented elephant trunk implantation for acute type A dissection under deep hypothermic circulatory arrest and selective antegrade cerebral perfusion.
      2008-201386ChinaAffiliated Hospital of Medical College, Qingdao University
      Zhang (2014)
      • Zhang H.
      • Lang X.
      • Lu F.
      • Song Z.
      • Wang J.
      • Han L.
      • et al.
      Acute type A dissection without intimal tear in arch: proximal or extensive repair?.
      2002-201088ChinaInstitute of Cardiothoracic Surgery, Changhai Hospital, Second Military Medical University
      Dias (2015)
      • Dias R.R.
      • Duncan J.A.
      • Vianna D.S.
      • de Faria L.B.
      • Fernandes F.
      • Ramirez F.J.
      • et al.
      Surgical treatment of complex aneurysms and thoracic aortic dissections with the Frozen Elephant Trunk technique.
      2009-201321BrazilHeart Institute of the University of São Paulo Medical School
      Hiraoka (2015)
      • Hiraoka A.
      • Chikazawa G.
      • Tamura K.
      • Totsugawa T.
      • Sakaguchi T.
      • Yoshitaka H.
      Clinical outcomes of different approaches to aortic arch disease.
      2005-201326JapanThe Sakakibara Heart Institute of Okayama
      Katayama (2015)
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      1997-2011224JapanHiroshima University Hospital; Hiroshima City Asa General Hospital
      Ahmad (2016)
      • El-Sayed Ahmad A.
      • Risteski P.
      • Papadopoulos N.
      • Radwan M.
      • Moritz A.
      • Zierer A.
      Minimally invasive approach for aortic arch surgery employing the frozen elephant trunk technique.
      2013-201514GermanyJohann-Wolfgang-Goethe University Frankfurt/Main, Frankfurt am Main, Germany
      Gong (2016)
      • Gong M.
      • Ma W.G.
      • Guan X.L.
      • Wang L.F.
      • Li J.C.
      • Lan F.
      • et al.
      Moderate hypothermic circulatory arrest in total arch repair for acute type A aortic dissection: clinical safety and efficacy.
      2014-201574ChinaBeijing Anzhen Hospital Capital Medical University and Beijing Institute of Heart Lung and Blood Vessel Disease
      Leontyev (2016)
      • Leontyev S.
      • Tsagakis K.
      • Pacini D.
      • Di Bartolomeo R.
      • Mohr F.W.
      • Weiss G.
      • et al.
      Impact of clinical factors and surgical techniques on early outcome of patients treated with frozen elephant trunk technique by using EVITA open stent-graft: results of a multicentre study.
      2005-2014509InternationalE-vita Open Registry
      Institutions included Leipzig Heart Center; West German Heart Centre Essen, University Hospital Essen; Sant'Orsola-Malpighi Hospital; Hospital Hietzing; Queen Elizabeth Hospital Birmingham; Robert Bosch Hospital; Tampere University Hospital Heart Center; Szpital Wojewódzki N2, OddziałKardiochirurgii; and Hospital Clinico, University of Barcelona.
      Ma (2016)
      • Ma M.
      • Liu L.
      • Feng X.
      • Wang Y.
      • Hu M.
      • Pan T.
      • et al.
      Moderate hypothermic circulatory arrest with antegrade cerebral perfusion for rapid total arch replacement in acute type A aortic dissection.
      2010-201399ChinaTongji Hospital, Tongji Medical College, Huazhong University of Science and Technology
      Shrestha (2016)
      • Shrestha M.
      • Kaufeld T.
      • Beckmann E.
      • Fleissner F.
      • Umminger J.
      • Abd Alhadi F.
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: single-center results of the first 100 patients.
      2010-2014100GermanyHannover Medical School
      Aalaei-Andabili (2017)
      • Aalaei-Andabili S.H.
      • Scali S.
      • Klodell C.
      • Lee T.
      • Hess P.
      • Martin T.
      • et al.
      Outcomes of antegrade stent graft deployment during hybrid aortic arch repair.
      2010-201548United StatesUniversity of Florida
      Chen (2017)
      • Chen L.
      • Qi R.D.
      • Liu W.
      • Li C.N.
      • Zhang N.
      • Zhu J.M.
      • et al.
      Repair of complicated chronic type B dissection with distal aortic arch involvement using left subclavian artery transposition with implantation of a stented elephant trunk.
      2011-201520ChinaBeijing Aortic Disease Center, Beijing Anzhen Hospital, Capital Medical University
      Hu (2017)
      • Hu X.
      • Wang Z.
      • Ren Z.
      • Hu R.
      • Wu H.
      Simplified total aortic arch replacement with an in situ stent graft fenestration technique for acute type A aortic dissection.
      2008-2015106ChinaRenmin Hospital of Wuhan University
      Preventza (2017)
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      2010-201537United StatesBaylor College of Medicine; Texas Heart Institute; Michael E. DeBakey Veterans Affairs Medical Center; Cleveland Clinic
      Verhoye (2017)
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      2009-201594FranceFrench multicenter
      Institutions included Pontchiallou University Hospital, Angers University Hospital, Reims University Hospital, and Louis Pradel University Hospital.
      Koizumi (2017)
      • Koizumi S.
      • Nagasawa A.
      • Koyama T.
      Total aortic arch replacement using frozen elephant trunk technique with J Graft Open Stent Graft for distal aortic arch aneurysm.
      2014-201630JapanKobe City Medical Center General Hospital
      Kreibich (2018)
      • Kreibich M.
      • Berger T.
      • Morlock J.
      • Kondov S.
      • Scheumann J.
      • Kari F.A.
      • et al.
      The frozen elephant trunk technique for the treatment of acute complicated type B aortic dissection.
      2015-201714GermanyUniversity of Freiburg
      Ma (2018)
      • Ma M.
      • Feng X.
      • Wang J.
      • Dong Y.
      • Chen T.
      • Liu L.
      • et al.
      Acute type I aortic dissection: a propensity-matched comparison of elephant trunk and arch debranching repairs.
      2013-2015132ChinaHuazhong University of Science and Technology
      Roselli (2018)
      • Roselli E.E.
      • Idrees J.J.
      • Bakaeen F.G.
      • Tong M.Z.
      • Soltesz E.G.
      • Mick S.
      • et al.
      Evolution of simplified frozen elephant trunk repair for acute DeBakey type I dissection: midterm outcomes.
      2009-201672United StatesCleveland Clinic
      N, Number of patients included in the study.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      Institutions included Beijing Aortic Disease Center, Beijing Anzhen Hospital of Capital Medical University, Beijing Institute of Heart, Lung and Blood Vessel Diseases, and Beijing Engineering Research Center of Vascular Prostheses; Fu Wai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Disease; and Aortic Institute at Yale-New Haven.
      Institutions included Leipzig Heart Center; West German Heart Centre Essen, University Hospital Essen; Sant'Orsola-Malpighi Hospital; Hospital Hietzing; Queen Elizabeth Hospital Birmingham; Robert Bosch Hospital; Tampere University Hospital Heart Center; Szpital Wojewódzki N2, OddziałKardiochirurgii; and Hospital Clinico, University of Barcelona.
      § Institutions included Pontchiallou University Hospital, Angers University Hospital, Reims University Hospital, and Louis Pradel University Hospital.
      The included studies were published between 2002 and 2018, and involved a total of 3154 patients (2274 male, 73.6% [95% CI, 70.6-76.4]) with a mean age of 55.3 years (95% CI, 51.3-59.3) (Table 3). Emergency repair was reported in 33 studies and performed in 1705 patients (53.2%). The mean hospital stay, which was reported in 9 studies, was 15.2 days (95% CI, 14.5-15.83), and the mean follow-up period (based on 15 studies) was 30.4 months (95% CI, 24.3-36.4).
      Table 3Summary of patient demographics
      Numbers are pooled data calculated in meta-analysis software that accounts for the differing weights of the studies.
      No. of publications reportingTotal N% or mean (95% CI)
      Total patients353154--
      Age (y)29278555.3 (51.3-59.3)
      Male33227473.6 (70.6-76.4)
      Urgent/emergency33170553.2 (40.4-65.7)
      Smoking615856.3 (46.2-66.0)
      Diabetes2024810.8 (7.6-15.2)
      Hypertension26203975.9 (71.3-79.9)
      Renal insufficiency242209.0 (6.2-13.0)
      CAD1925112.0 (7.9-17.9)
      COPD1727318.4 (13.3-24.8)
      Previous sternotomies87518.5 (9.7-32.4)
      Previous aortic/cardiac complications1232231.5 (19.8-46.0)
      Prior stroke191587.2 (4.7-10.8)
      CPB time (min)292619203.6 (191.7-215.5)
      Follow-up (mo)1574230.4 (24.3-36.4)
      Hospital stay (d)945915.2 (14.5-15.8)
      CI, Confidence interval; CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; CPB, cardiopulmonary bypass.
      Numbers are pooled data calculated in meta-analysis software that accounts for the differing weights of the studies.
      Various stents and devices were used: Jotec E-vita (Jotec GmbH, Hechingen, Germany), stainless steel Gianturco Z (Cook Group, Inc, Bloomington, Ind), Chavan-Haverich Prosthesis (Curative GmbH, Dresden, Germany), Cronus (MicroPort Medical Co, Ltd, Shanghai, China), Thoraflex Hybrid Prosthesis (Vascutek, Terumo, Inchinnan, Scotland, UK), and E-Vita Open and E-Vita Open Plus (Jotec GmbH, Hechingen, Germany). In addition, some investigators used custom-made FET devices with the addition of an intact or modified Gore TAG (WL Gore and Associates, Flagstaff, Ariz), Medtronic Valiant (Medtronic, Santa Rosa, Calif), or Cook endograft (Cook Group, Bloomington, Ind). Also, another custom-made stent was used that comprised a double-linked 10-bend Z stent sutured into an ultrathin woven Dacron graft. One series used a vascular graft (Yuhengjia Sci-Tech Co Ltd, Beijing, China) with the addition of a single-branch graft (Intervascular InterGard Knitted Graft; Datascope Co, Montvale, NJ).

      Neurologic Morbidity

      Clinical outcomes, including overall (ie, both permanent and transient) stroke and SCI, (paralysis, paraplegia, or paraparesis) are summarized in Table 4. The rate of overall stroke (temporary and permanent) ranged from 0% to 40.9%, and the rate of any spinal cord adverse event ranged from 0% to 24.0%. The pooled outcome rates (95% CI) with corresponding results of heterogeneity and publication bias are shown in Table 5.
      Table 4Summary of clinical outcomes
      First author (year)NOverall strokeOverall SCI/paralysis/paraplegiaOperative mortality
      % (95% CI)% (95% CI)% (95% CI)
      Usui (2002)
      • Usui A.
      • Fujimoto K.
      • Ishiguchi T.
      • Yoshikawa M.
      • Akita T.
      • Ueda Y.
      Cerebrospinal dysfunction after endovascular stent-grafting via a median sternotomy: the frozen elephant trunk procedure.
      244.2 (0.0-12.2)12.5 (0.0-25.7)0.0 (0.0-0.0)
      Flores (2006)
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      2516.0 (1.6-30.4)24.0 (7.3-40.7)12.0 (0.0-24.7)
      Shimamura (2008)
      • Shimamura K.
      • Kuratani T.
      • Matsumiya G.
      • Kato M.
      • Shirakawa Y.
      • Takano H.
      • et al.
      Long-term results of the open stent-grafting technique for extended aortic arch disease.
      1265.6 (1.6-9.6)6.3 (2.1-10.6)5.6 (1.6-9.6)
      Li (2009)
      • Li B.
      • Sun L.
      • Chang Q.
      • Zhu J.
      • Yu C.
      • Liu Y.
      • et al.
      Total arch replacement with stented elephant trunk technique: a proposed treatment for complicated Stanford type B aortic dissection.
      313.2 (0.0-9.4)0.0 (0.0-0.0)6.5 (0.0-15.1)
      Chen (2010)
      • Chen X.
      • Huang F.
      • Xu M.
      • Wang L.
      • Jiang Y.
      • Xiao L.
      • et al.
      The stented elephant trunk procedure combined total arch replacement for DeBakey I aortic dissection: operative result and follow-up.
      2810.7 (0.0-22.2)0.0 (0.0-0.0)14.3 (1.3-27.2)
      Sun (2010)
      • Sun L.
      • Zhao X.
      • Chang Q.
      • Zhu J.
      • Liu Y.
      • Yu C.
      • et al.
      Repair of chronic type B dissection with aortic arch involvement using a stented elephant trunk procedure.
      195.3 (0.0-15.3)0.0 (0.0-0.0)5.3 (0.0-15.3)
      Lima (2012)
      • Lima B.
      • Roselli E.E.
      • Soltesz E.G.
      • Johnston D.R.
      • Pujara A.C.
      • Idrees J.
      • et al.
      Modified and “reverse” frozen elephant trunk repairs for extensive disease and complications after stent grafting.
      3112.9 (1.1-24.7)12.9 (1.1-24.7)9.7 (0.0-20.1)
      Shen (2012)
      • Shen K.
      • Tang H.
      • Jing R.
      • Liu F.
      • Zhou X.
      Application of triple-branched stent graft for Stanford type A aortic dissection: potential risks.
      380.0 (0.0-0.0)5.3 (0.0-12.4)7.9 (0.0-16.5)
      Zhao (2012)
      • Zhao H.P.
      • Zhu J.M.
      • Ma W.G.
      • Zheng J.
      • Liu Y.M.
      • Sun L.Z.
      Total arch replacement with stented elephant trunk technique for acute type B aortic dissection involving the aortic arch.
      244.2 (0.0-12.2)0.0 (0.0-0.0)4.2 (0.0-12.2)
      Hoffman (2013)
      • Hoffman A.
      • Damberg A.L.M.
      • Schalte G.
      • Mahnken A.H.
      • Raweh A.
      • Autschbach R.
      Thoracic stent graft sizing for frozen elephant trunk repair in acute type A dissection.
      320.0 (0.0-0.0)0.0 (0.0-0.0)3.1 (0.0-9.2)
      Di Marco (2014)
      • Di Marco L.
      • Pacini D.
      • Leone A.
      • Pantaleo A.
      • Cefarelli M.
      • Di Eusanio M.
      The Thoraflex hybrid frozen elephant trunk device: the Bologna experience.
      119.1 (0.0-26.1)0.0 (0.0-0.0)0.0 (0.0-0.0)
      Ma (2014)
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      4562.9 (1.3-4.4)2.4 (1.0-3.8)8.1 (5.6-10.6)
      Ma (2014B)
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      3470.9 (0.0-1.8)2.3 (0.7-3.9)4.3 (2.2-6.5)
      Nakamura (2014)
      • Nakamura K.
      • Nagahama H.
      • Nakamura E.
      • Yano M.
      • Matsuyama M.
      • Nishimura M.
      • et al.
      Predictors of early and late outcome after total arch replacement for atherosclerotic aortic arch aneurysm.
      51NR3.9 (0.0-9.2)NR
      Shi (2014)
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      8433.3 (23.3-43.4)0.0 (0.0-0.0)6.0 (0.9-11.0)
      Xiao (2014)
      • Xiao Z.
      • Meng W.
      • Zhu D.
      • Guo Y.
      • Zhang E.
      Treatment strategies for left subclavian artery during total arch replacement combined with stented elephant trunk implantation.
      330.0 (0.0-0.0)0.0 (0.0-0.0)18.2 (5.0-31.3)
      Yang (2014)
      • Yang S.M.
      • Xu P.
      • Li C.X.
      • Huang Q.
      • Gao H.B.
      • Li Z.F.
      • et al.
      A modified total arch replacement combined with a stented elephant trunk implantation for acute type A dissection under deep hypothermic circulatory arrest and selective antegrade cerebral perfusion.
      86NR2.3 (0.0-5.5)5.8 (0.9-10.8)
      Zhang (2014)
      • Zhang H.
      • Lang X.
      • Lu F.
      • Song Z.
      • Wang J.
      • Han L.
      • et al.
      Acute type A dissection without intimal tear in arch: proximal or extensive repair?.
      8814.8 (7.4-22.2)0.0 (0.0-0.0)5.7 (0.8-10.5)
      Dias (2015)
      • Dias R.R.
      • Duncan J.A.
      • Vianna D.S.
      • de Faria L.B.
      • Fernandes F.
      • Ramirez F.J.
      • et al.
      Surgical treatment of complex aneurysms and thoracic aortic dissections with the Frozen Elephant Trunk technique.
      214.8 (0.0-13.9)9.5 (0.0-22.1)14.3 (0.0-29.3)
      Hiraoka (2015)
      • Hiraoka A.
      • Chikazawa G.
      • Tamura K.
      • Totsugawa T.
      • Sakaguchi T.
      • Yoshitaka H.
      Clinical outcomes of different approaches to aortic arch disease.
      267.7 (0.0-17.9)11.5 (0.0-23.8)0.0 (0.0-0.0)
      Katayama (2015)
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      2242.7 (0.6-4.8)3.6 (1.1-6.0)3.6 (1.1-6.0)
      Ahmad (2016)
      • El-Sayed Ahmad A.
      • Risteski P.
      • Papadopoulos N.
      • Radwan M.
      • Moritz A.
      • Zierer A.
      Minimally invasive approach for aortic arch surgery employing the frozen elephant trunk technique.
      1414.3 (0.0-32.6)0.0 (0.0-0.0)0.0 (0.0-0.0)
      Gong (2016)
      • Gong M.
      • Ma W.G.
      • Guan X.L.
      • Wang L.F.
      • Li J.C.
      • Lan F.
      • et al.
      Moderate hypothermic circulatory arrest in total arch repair for acute type A aortic dissection: clinical safety and efficacy.
      746.8 (1.0-12.5)6.8 (1.0-12.5)12.2 (4.7-19.6)
      Leontyev (2016)
      • Leontyev S.
      • Tsagakis K.
      • Pacini D.
      • Di Bartolomeo R.
      • Mohr F.W.
      • Weiss G.
      • et al.
      Impact of clinical factors and surgical techniques on early outcome of patients treated with frozen elephant trunk technique by using EVITA open stent-graft: results of a multicentre study.
      5098.1 (5.7-10.4)7.5 (5.2-9.7)15.9 (12.7-19.1)
      Ma (2016)
      • Ma M.
      • Liu L.
      • Feng X.
      • Wang Y.
      • Hu M.
      • Pan T.
      • et al.
      Moderate hypothermic circulatory arrest with antegrade cerebral perfusion for rapid total arch replacement in acute type A aortic dissection.
      9934.3 (25.0-43.7)0.0 (0.0-0.0)17.2 (9.7-24.6)
      Shrestha (2016)
      • Shrestha M.
      • Kaufeld T.
      • Beckmann E.
      • Fleissner F.
      • Umminger J.
      • Abd Alhadi F.
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: single-center results of the first 100 patients.
      1009.0 (3.4-14.6)7.0 (2.0-12.0)7.0 (2.0-12.0)
      Aalaei-Andabili (2017)
      • Aalaei-Andabili S.H.
      • Scali S.
      • Klodell C.
      • Lee T.
      • Hess P.
      • Martin T.
      • et al.
      Outcomes of antegrade stent graft deployment during hybrid aortic arch repair.
      486.3 (0.0-13.1)4.2 (0.0-9.8)16.7 (6.1-27.2)
      Chen (2017)
      • Chen L.
      • Qi R.D.
      • Liu W.
      • Li C.N.
      • Zhang N.
      • Zhu J.M.
      • et al.
      Repair of complicated chronic type B dissection with distal aortic arch involvement using left subclavian artery transposition with implantation of a stented elephant trunk.
      20NR5.0 (0.0-14.6)5.0 (0.0-14.6)
      Hu (2017)
      • Hu X.
      • Wang Z.
      • Ren Z.
      • Hu R.
      • Wu H.
      Simplified total aortic arch replacement with an in situ stent graft fenestration technique for acute type A aortic dissection.
      1064.7 (0.7-8.8)0.0 (0.0-0.0)7.5 (2.5-12.6)
      Preventza (2017)
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      375.4 (0.0-12.7)5.4 (0.0-12.7)21.6 (8.4-34.9)
      Verhoye (2017)
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      949.6 (3.6-15.5)4.3 (0.2-8.3)11.7 (5.2-18.2)
      Koizumi (2017)
      • Koizumi S.
      • Nagasawa A.
      • Koyama T.
      Total aortic arch replacement using frozen elephant trunk technique with J Graft Open Stent Graft for distal aortic arch aneurysm.
      3010.0 (0.0-20.7)3.3 (0.0-9.8)0.0 (0.0-0.0)
      Kreibich (2018)
      • Kreibich M.
      • Berger T.
      • Morlock J.
      • Kondov S.
      • Scheumann J.
      • Kari F.A.
      • et al.
      The frozen elephant trunk technique for the treatment of acute complicated type B aortic dissection.
      1414.3 (0.0-32.6)0.0 (0.0-0.0)0.0 (0.0-0.0)
      Ma (2018)
      • Ma M.
      • Feng X.
      • Wang J.
      • Dong Y.
      • Chen T.
      • Liu L.
      • et al.
      Acute type I aortic dissection: a propensity-matched comparison of elephant trunk and arch debranching repairs.
      13240.9 (32.5-49.3)0.0 (0.0-0.0)14.4 (8.4-20.4)
      Roselli (2018)
      • Roselli E.E.
      • Idrees J.J.
      • Bakaeen F.G.
      • Tong M.Z.
      • Soltesz E.G.
      • Mick S.
      • et al.
      Evolution of simplified frozen elephant trunk repair for acute DeBakey type I dissection: midterm outcomes.
      722.8 (0.0-6.6)4.2 (0.0-8.8)4.2 (0.0-8.8)
      All studies (range)31540-40.90-24.00-21.6
      N, Number of patients included in study; SCI, spinal cord ischemia; CI, confidence interval; NR, not reported.
      Upper entry, labeled Ma (2014), refers to data from acute cases; lower entry, labeled Ma (2014B), refers to data from chronic cases.
      Table 5Pooled outcome rates (95% confidence intervals), with corresponding results of heterogeneity and publication bias
      OutcomeNo. of studiesPooled rate, % (95% CI)Heterogeneity I2% (95% CI) prediction intervalPublication bias Egger test P (1-tailed)
      Overall stroke327.6 (5.0-11.5)88.3 (84.5-91.1)

      2.9-12.3
      .003
      Overall SCI354.7 (3.5-6.2)46.3 (20.1-63.9)

      2.8-6.6
      .008
      Operative mortality348.8 (7.0-10.9)60.5 (42.5-72.8)

      6.4-11.2
      .002
      CI, Confidence interval; SCI, spinal cord ischemia.
      The proportional meta-analysis for overall permanent or transient stroke as reported in 32 studies showed a pooled estimate of 7.6% (95% CI, 5.0-11.5), albeit with high heterogeneity (I2 = 88.3%) (Figure 2). The prediction interval taking the heterogeneity into account indicated that 95% of the population would be within the range of 2.9% to 12.3%. Publication bias was seen both qualitatively (asymmetry in the funnel plot, with missing studies to the right) and quantitatively (Egger P = .003) (Figure 3).
      Figure thumbnail gr2a
      Figure 2Event rates for adverse outcomes. Forest plots show the event rates for (A) overall, persistent, or transient stroke (7.6%; 95% CI, 5.0-11.5); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (4.7%; 95% CI, 3.5-6.2); and (C) overall, operative, 30-day, or in-hospital mortality (8.8%; 95% CI, 7.0-10.9). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The summary pooled event rate is represented by the middle of the solid red diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.
      Figure thumbnail gr2b
      Figure 2Event rates for adverse outcomes. Forest plots show the event rates for (A) overall, persistent, or transient stroke (7.6%; 95% CI, 5.0-11.5); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (4.7%; 95% CI, 3.5-6.2); and (C) overall, operative, 30-day, or in-hospital mortality (8.8%; 95% CI, 7.0-10.9). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The summary pooled event rate is represented by the middle of the solid red diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.
      Figure thumbnail gr2c
      Figure 2Event rates for adverse outcomes. Forest plots show the event rates for (A) overall, persistent, or transient stroke (7.6%; 95% CI, 5.0-11.5); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (4.7%; 95% CI, 3.5-6.2); and (C) overall, operative, 30-day, or in-hospital mortality (8.8%; 95% CI, 7.0-10.9). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The summary pooled event rate is represented by the middle of the solid red diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.
      Figure thumbnail gr3
      Figure 3Logit event rates for adverse outcomes. Funnel plots show these rates for (A) stroke (11.0%; 95% CI, 7.9-16.0), (B) spinal cord injury (6.1%; 95% CI, 4.6-8.1), and (C) mortality (10.1%; 95% CI, 8.2-12.4). Blue circles represent the studies used in the analysis, and red circles represent the studies that were imputed with the trim-and-fill method. Note: “Ma (2014)” refers to data from acute cases; “Ma (2014B)” refers to data from chronic cases in the same study.
      The pooled rate for overall SCI (paralysis, paraplegia, or paraparesis) was 4.7% (95% CI, 3.5-6.2), with I2 = 46.3% indicating low heterogeneity (Figure 2). Taking this heterogeneity into account yielded a prediction interval of 2.8% to 6.6%, which is the range into which 95% of the population would have been. Publication bias was seen both qualitatively (asymmetry in the funnel plot, with missing studies to the right) and quantitatively (Egger P = .008) (Figure 3). All 35 articles reported SCI data.

      Operative Mortality

      The rate of operative mortality (variously reported as operative, 30-day, and in-hospital mortality) ranged from 0% to 21.6%. One study did not report operative mortality specifically for FET
      • Nakamura K.
      • Nagahama H.
      • Nakamura E.
      • Yano M.
      • Matsuyama M.
      • Nishimura M.
      • et al.
      Predictors of early and late outcome after total arch replacement for atherosclerotic aortic arch aneurysm.
      ; for the remaining 34 studies, the total pooled operative mortality rate was 8.8% (95% CI, 7.0-10.9) (Figure 2). The I2 = 60.5% indicates moderate heterogeneity. The prediction interval taking the heterogeneity into account indicated that 95% of the population would be within the range of 6.4% to 11.2%. Publication bias was seen both qualitatively (asymmetry in the funnel plot with missing studies to the right) and quantitatively (Egger P = .002) (Figure 3).

      Subgroup Analysis

      Spinal cord coverage T8 or beyond (or stent length ≥15 cm) and spinal cord ischemia

      We compared studies performed only in patients with spinal cord coverage T8 or beyond or 15 cm or greater stent length (n = 6, 201 patients),
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      ,
      • Hoffman A.
      • Damberg A.L.M.
      • Schalte G.
      • Mahnken A.H.
      • Raweh A.
      • Autschbach R.
      Thoracic stent graft sizing for frozen elephant trunk repair in acute type A dissection.
      ,
      • Hiraoka A.
      • Chikazawa G.
      • Tamura K.
      • Totsugawa T.
      • Sakaguchi T.
      • Yoshitaka H.
      Clinical outcomes of different approaches to aortic arch disease.
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      • El-Sayed Ahmad A.
      • Risteski P.
      • Papadopoulos N.
      • Radwan M.
      • Moritz A.
      • Zierer A.
      Minimally invasive approach for aortic arch surgery employing the frozen elephant trunk technique.
      ,
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      with studies performed only in patients with stent length equal to 10 cm (n = 19, 1634 patients).
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      ,
      • Li B.
      • Sun L.
      • Chang Q.
      • Zhu J.
      • Yu C.
      • Liu Y.
      • et al.
      Total arch replacement with stented elephant trunk technique: a proposed treatment for complicated Stanford type B aortic dissection.
      • Chen X.
      • Huang F.
      • Xu M.
      • Wang L.
      • Jiang Y.
      • Xiao L.
      • et al.
      The stented elephant trunk procedure combined total arch replacement for DeBakey I aortic dissection: operative result and follow-up.
      • Sun L.
      • Zhao X.
      • Chang Q.
      • Zhu J.
      • Liu Y.
      • Yu C.
      • et al.
      Repair of chronic type B dissection with aortic arch involvement using a stented elephant trunk procedure.
      ,
      • Shen K.
      • Tang H.
      • Jing R.
      • Liu F.
      • Zhou X.
      Application of triple-branched stent graft for Stanford type A aortic dissection: potential risks.
      ,
      • Zhao H.P.
      • Zhu J.M.
      • Ma W.G.
      • Zheng J.
      • Liu Y.M.
      • Sun L.Z.
      Total arch replacement with stented elephant trunk technique for acute type B aortic dissection involving the aortic arch.
      ,
      • Di Marco L.
      • Pacini D.
      • Leone A.
      • Pantaleo A.
      • Cefarelli M.
      • Di Eusanio M.
      The Thoraflex hybrid frozen elephant trunk device: the Bologna experience.
      ,
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      ,
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      ,
      • Xiao Z.
      • Meng W.
      • Zhu D.
      • Guo Y.
      • Zhang E.
      Treatment strategies for left subclavian artery during total arch replacement combined with stented elephant trunk implantation.
      ,
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      ,
      • Gong M.
      • Ma W.G.
      • Guan X.L.
      • Wang L.F.
      • Li J.C.
      • Lan F.
      • et al.
      Moderate hypothermic circulatory arrest in total arch repair for acute type A aortic dissection: clinical safety and efficacy.
      ,
      • Ma M.
      • Liu L.
      • Feng X.
      • Wang Y.
      • Hu M.
      • Pan T.
      • et al.
      Moderate hypothermic circulatory arrest with antegrade cerebral perfusion for rapid total arch replacement in acute type A aortic dissection.
      ,
      • Chen L.
      • Qi R.D.
      • Liu W.
      • Li C.N.
      • Zhang N.
      • Zhu J.M.
      • et al.
      Repair of complicated chronic type B dissection with distal aortic arch involvement using left subclavian artery transposition with implantation of a stented elephant trunk.
      • Hu X.
      • Wang Z.
      • Ren Z.
      • Hu R.
      • Wu H.
      Simplified total aortic arch replacement with an in situ stent graft fenestration technique for acute type A aortic dissection.
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      ,
      • Kreibich M.
      • Berger T.
      • Morlock J.
      • Kondov S.
      • Scheumann J.
      • Kari F.A.
      • et al.
      The frozen elephant trunk technique for the treatment of acute complicated type B aortic dissection.
      ,
      • Ma M.
      • Feng X.
      • Wang J.
      • Dong Y.
      • Chen T.
      • Liu L.
      • et al.
      Acute type I aortic dissection: a propensity-matched comparison of elephant trunk and arch debranching repairs.
      The patients with coverage beyond T8 or stent length 15 cm or greater had a significantly higher incidence of SCI (11.6% [95% CI, 6.1-21.1] vs 2.5% [95% CI, 1.5-4.0], P < .001) (Figure E1).

      Acute Type A versus Nonacute Type A and Aneurysm

      When we compared studies performed only in patients with acute type A aortic dissection (n = 12, 1300 patients)
      • Shen K.
      • Tang H.
      • Jing R.
      • Liu F.
      • Zhou X.
      Application of triple-branched stent graft for Stanford type A aortic dissection: potential risks.
      ,
      • Hoffman A.
      • Damberg A.L.M.
      • Schalte G.
      • Mahnken A.H.
      • Raweh A.
      • Autschbach R.
      Thoracic stent graft sizing for frozen elephant trunk repair in acute type A dissection.
      ,
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      ,
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      • Xiao Z.
      • Meng W.
      • Zhu D.
      • Guo Y.
      • Zhang E.
      Treatment strategies for left subclavian artery during total arch replacement combined with stented elephant trunk implantation.
      • Yang S.M.
      • Xu P.
      • Li C.X.
      • Huang Q.
      • Gao H.B.
      • Li Z.F.
      • et al.
      A modified total arch replacement combined with a stented elephant trunk implantation for acute type A dissection under deep hypothermic circulatory arrest and selective antegrade cerebral perfusion.
      • Zhang H.
      • Lang X.
      • Lu F.
      • Song Z.
      • Wang J.
      • Han L.
      • et al.
      Acute type A dissection without intimal tear in arch: proximal or extensive repair?.
      ,
      • Gong M.
      • Ma W.G.
      • Guan X.L.
      • Wang L.F.
      • Li J.C.
      • Lan F.
      • et al.
      Moderate hypothermic circulatory arrest in total arch repair for acute type A aortic dissection: clinical safety and efficacy.
      ,
      • Ma M.
      • Liu L.
      • Feng X.
      • Wang Y.
      • Hu M.
      • Pan T.
      • et al.
      Moderate hypothermic circulatory arrest with antegrade cerebral perfusion for rapid total arch replacement in acute type A aortic dissection.
      ,
      • Hu X.
      • Wang Z.
      • Ren Z.
      • Hu R.
      • Wu H.
      Simplified total aortic arch replacement with an in situ stent graft fenestration technique for acute type A aortic dissection.
      ,
      • Ma M.
      • Feng X.
      • Wang J.
      • Dong Y.
      • Chen T.
      • Liu L.
      • et al.
      Acute type I aortic dissection: a propensity-matched comparison of elephant trunk and arch debranching repairs.
      ,
      • Roselli E.E.
      • Idrees J.J.
      • Bakaeen F.G.
      • Tong M.Z.
      • Soltesz E.G.
      • Mick S.
      • et al.
      Evolution of simplified frozen elephant trunk repair for acute DeBakey type I dissection: midterm outcomes.
      with studies performed only in patients with nonacute type A dissection and aneurysm (n = 14, 741 patients),
      • Usui A.
      • Fujimoto K.
      • Ishiguchi T.
      • Yoshikawa M.
      • Akita T.
      • Ueda Y.
      Cerebrospinal dysfunction after endovascular stent-grafting via a median sternotomy: the frozen elephant trunk procedure.
      ,
      • Flores J.
      • Kunihara T.
      • Shiiya N.
      • Yoshimoto K.
      • Matsuzaki K.
      • Yasuda K.
      Extensive deployment of the stented elephant trunk is associated with an increased risk of spinal cord injury.
      ,
      • Li B.
      • Sun L.
      • Chang Q.
      • Zhu J.
      • Yu C.
      • Liu Y.
      • et al.
      Total arch replacement with stented elephant trunk technique: a proposed treatment for complicated Stanford type B aortic dissection.
      ,
      • Sun L.
      • Zhao X.
      • Chang Q.
      • Zhu J.
      • Liu Y.
      • Yu C.
      • et al.
      Repair of chronic type B dissection with aortic arch involvement using a stented elephant trunk procedure.
      ,
      • Zhao H.P.
      • Zhu J.M.
      • Ma W.G.
      • Zheng J.
      • Liu Y.M.
      • Sun L.Z.
      Total arch replacement with stented elephant trunk technique for acute type B aortic dissection involving the aortic arch.
      ,
      • Di Marco L.
      • Pacini D.
      • Leone A.
      • Pantaleo A.
      • Cefarelli M.
      • Di Eusanio M.
      The Thoraflex hybrid frozen elephant trunk device: the Bologna experience.
      • Ma W.G.
      • Zheng J.
      • Zhang W.
      • Sun K.
      • Ziganshin B.A.
      • Wang L.F.
      • et al.
      Frozen elephant trunk with total arch replacement for type A aortic dissections: does acuity affect operative mortality?.
      • Nakamura K.
      • Nagahama H.
      • Nakamura E.
      • Yano M.
      • Matsuyama M.
      • Nishimura M.
      • et al.
      Predictors of early and late outcome after total arch replacement for atherosclerotic aortic arch aneurysm.
      ,
      • El-Sayed Ahmad A.
      • Risteski P.
      • Papadopoulos N.
      • Radwan M.
      • Moritz A.
      • Zierer A.
      Minimally invasive approach for aortic arch surgery employing the frozen elephant trunk technique.
      ,
      • Chen L.
      • Qi R.D.
      • Liu W.
      • Li C.N.
      • Zhang N.
      • Zhu J.M.
      • et al.
      Repair of complicated chronic type B dissection with distal aortic arch involvement using left subclavian artery transposition with implantation of a stented elephant trunk.
      ,
      • Preventza O.
      • Coselli J.S.
      • Mayor J.
      • Simpson K.
      • Carillo J.
      • Price M.D.
      • et al.
      The stent is not to blame: lessons learned with a simplified US version of the frozen elephant trunk.
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      • Koizumi S.
      • Nagasawa A.
      • Koyama T.
      Total aortic arch replacement using frozen elephant trunk technique with J Graft Open Stent Graft for distal aortic arch aneurysm.
      • Kreibich M.
      • Berger T.
      • Morlock J.
      • Kondov S.
      • Scheumann J.
      • Kari F.A.
      • et al.
      The frozen elephant trunk technique for the treatment of acute complicated type B aortic dissection.
      we found the following results: The pooled mortality rate was 9.2% (95% CI, 6.9-12.4) in the patients with acute type A and 7.6% (95% CI, 4.9-11.4) in the patients with nonacute dissection and aneurysm (P = .46). The pooled rate of stroke in these 2 groups was 9.3% (95% CI, 4.5-18.5) and 6.6% (95% CI, 3.1-13.5) (P = .51), and the pooled rate of SCI was 2.4% (95% CI, 1.3-4.2) and 5.2% (95% CI, 3.1-8.5) (P = .05), respectively (Figure E2).
      The incidence of the overall composite adverse outcome (mortality, stroke, and SCI) was 22.0% (95% CI, 13.6-33.6) for the acute type A aortic dissection group and 16.5% (95% CI 9.6-26.7) for the nonacute dissection and aneurysm groups (P = .41).

      Discussion

      Since the original description of extensive aortic replacement using the ET technique by Borst and colleagues,
      • Borst H.G.
      • Walterbusch G.
      • Schaps D.
      Extensive aortic replacement using “elephant trunk” prosthesis.
      techniques and technology have continued to develop in an effort to simplify complex aortic repairs. The evidence is ambiguous regarding the value of FET repair for extensive aortic pathologies. Kato and colleagues
      • Kato M.
      • Ohnishi K.
      • Kaneko M.
      • Ueda T.
      • Kishi D.
      • Mizushima T.
      • et al.
      New graft-implanting method for thoracic aortic aneurysm or dissection with a stented graft.
      introduced the placement of an endovascular prosthesis in the descending thoracic aorta; since then, few single-device hybrid endoprostheses have been used in Europe and Asia. Additionally, custom-made devices have become popular. The expected benefits of FET are 2-fold: It allows debranching of the arch vessels and arch replacement by an open technique and creates an optimal proximal landing zone for thoracic endovascular repair of the remaining descending thoracic aorta, which can be achieved in the same operative session or in a second stage by retrograde stent delivery. A virtual seal in the descending thoracic aorta also can be achieved. Second-stage repair of the entire thoracoabdominal aorta also can be accomplished by open repair, total endovascular repair with custom-made branched endografts, or hybrid repair.
      In the present meta-analysis, we reviewed the reported data for 3145 patients from 35 studies, with a focus on mortality and neurologic events associated with this procedure (Figure 4). The 8.8% pooled rate of overall mortality is similar to rates produced by other meta-analyses,
      • Hanif H.
      • Dubois L.
      • Ouzounian M.
      • Peterson M.D.
      • El-Hamamsy I.
      • Dagenais F.
      • et al.
      Aortic arch reconstructive surgery with conventional techniques vs frozen elephant trunk: a systematic review and meta-analysis.
      ,
      • Tian D.H.
      • Wan B.
      • Di Eusanio M.
      • Black D.
      • Yan T.D.
      A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery.
      although our analysis included only total arch FET procedures, whereas the others
      • Hanif H.
      • Dubois L.
      • Ouzounian M.
      • Peterson M.D.
      • El-Hamamsy I.
      • Dagenais F.
      • et al.
      Aortic arch reconstructive surgery with conventional techniques vs frozen elephant trunk: a systematic review and meta-analysis.
      ,
      • Tian D.H.
      • Wan B.
      • Di Eusanio M.
      • Black D.
      • Yan T.D.
      A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery.
      included both total arch operations with FET and proximal arch procedures with stenting of the descending thoracic aorta.
      Figure thumbnail gr4
      Figure 4A visual summary of the main points of our study. The overall pooled rates of the outcomes of interest were 4.7% for overall SCI, 7.6% for overall stroke, and 8.8% for operative mortality. Additionally, 2 subgroup analyses were performed: One showed that SCI was significantly more frequent in the patients with longer stents or coverage at or beyond T8. The other subgroup analysis found that the FET technique was associated with higher rates of mortality and stroke in patients with acute type A dissection, and the overall adverse event rate (which included mortality, stroke, and SCI) was higher in these patients, too. FET, Frozen elephant trunk; SC, spinal cord; SCI, spinal cord ischemia.
      This mortality rate, which reflects all emergency (53.2%) and elective cases, is less than the 14.5% rate reported for conventional ET procedures in a recent systematic review.
      • Hanif H.
      • Dubois L.
      • Ouzounian M.
      • Peterson M.D.
      • El-Hamamsy I.
      • Dagenais F.
      • et al.
      Aortic arch reconstructive surgery with conventional techniques vs frozen elephant trunk: a systematic review and meta-analysis.
      One possible explanation is that FET procedures are more likely than conventional ET procedures to be performed in specialized aortic surgery centers with access to specific devices.
      We found that the pooled estimate for overall permanent or transient stroke reported in 32 studies was 7.6%, which is similar to what is reported for the conventional ET repair (Figure 4).
      • Hanif H.
      • Dubois L.
      • Ouzounian M.
      • Peterson M.D.
      • El-Hamamsy I.
      • Dagenais F.
      • et al.
      Aortic arch reconstructive surgery with conventional techniques vs frozen elephant trunk: a systematic review and meta-analysis.
      However, it is higher than what was reported in the previous FET meta-analyses.
      • Hanif H.
      • Dubois L.
      • Ouzounian M.
      • Peterson M.D.
      • El-Hamamsy I.
      • Dagenais F.
      • et al.
      Aortic arch reconstructive surgery with conventional techniques vs frozen elephant trunk: a systematic review and meta-analysis.
      ,
      • Tian D.H.
      • Wan B.
      • Di Eusanio M.
      • Black D.
      • Yan T.D.
      A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery.
      This difference can be explained by our including only studies of total arch procedures, which are more complex and lengthy—and thus may incur a higher risk of stroke—than proximal arch or hemiarch procedures. The mode of cerebral perfusion used in the included studies was variously antegrade cerebral perfusion, retrograde cerebral perfusion, and a combination of both, with the most common being antegrade cerebral perfusion. Various levels of hypothermia were used in the studies. Unfortunately, because the studies varied in the ways in which temperatures were measured (rectal or nasopharyngeal) and reported (mean with standard deviation, mean with range, range only), we were not able to examine the relation between hypothermic temperature and overall stroke risk.
      Of the 35 FET studies, 12 included only acute type A aortic dissection cases. The overall composite adverse event rate was slightly higher in the acute type A aortic dissection cases than in the nonacute and aneurysm cases, as were the rates of operative mortality and stroke (Figure 4). This may reflect the urgency of performing a type A dissection procedure and the complexity of the total arch procedure in these patients, whose preoperative characteristics may include preoperative malperfusion, instability, and occasional poor preoperative neurologic status, which have specific implications for acute type A dissection cases and can drive a dismal outcome. We did notice less SCI overall with the acute dissection cases than with the nonacute dissection and aneurysm cases, maybe because these patients' higher rates of mortality and stroke resulted in fewer of them being evaluated for spinal cord deficit. In addition, the status of patency of the false lumen and its effect on the risk of spinal cord deficit are unknown.
      Paralysis and paraparesis are potentially deadly adverse consequences of thoracic endovascular repair, and they remain a major concern with the FET procedure. Data regarding spinal cord protection from thoracic endovascular aortic repair and open thoracoabdominal procedures
      • Etz C.D.
      • Weigang E.
      • Hartert M.
      • Lonn L.
      • Mestres C.A.
      • Di Bartolomeo R.
      • et al.
      Contemporary spinal cord protection during thoracic and thoracoabdominal aortic surgery and endovascular aortic repair: a position paper of the vascular domain of the European Association for Cardio-Thoracic Surgery.
      can be used to guide FET procedures. As more data have become available regarding the potential for spinal cord compromise, lessons have been learned and registries have been created
      • Leontyev S.
      • Tsagakis K.
      • Pacini D.
      • Di Bartolomeo R.
      • Mohr F.W.
      • Weiss G.
      • et al.
      Impact of clinical factors and surgical techniques on early outcome of patients treated with frozen elephant trunk technique by using EVITA open stent-graft: results of a multicentre study.
      ,
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      ,
      • Pacini D.
      • Tsagakis K.
      • Jakob H.
      • Mestres C.A.
      • Armaro A.
      • Weiss G.
      • et al.
      The frozen elephant trunk for the treatment of chronic dissection of the thoracic aorta: a multicenter experience.
      to capture procedures and outcomes and to examine the association between extensive spinal cord coverage and paralysis or paraparesis.
      In the International E-vita Open Registry,
      • Pacini D.
      • Tsagakis K.
      • Jakob H.
      • Mestres C.A.
      • Armaro A.
      • Weiss G.
      • et al.
      The frozen elephant trunk for the treatment of chronic dissection of the thoracic aorta: a multicenter experience.
      among 90 patients who underwent procedures for chronic dissection (which was type A in 77% of the cases) of the thoracic aorta, 8 (8.9%) developed SCI. Although no correlation between extensive coverage with the FET and SCI was seen in that study, the rate of SCI was higher in patients whose distal landing zone was at or below T10, and no patient with SCI had stent coverage to less than T8. In our meta-analysis, we saw significantly higher rates of paralysis or paraparesis in patients with coverage at T8 or beyond or a stent length of 15 cm or longer (11.6% vs 2.5%, P < .001) compared with a length of 10 cm (Figure 4). We acknowledge that the exact location of the suture line proximal or distal to the left subclavian artery, which could affect thoracic spine coverage, was not consistently clear in the articles included in our analysis. Use of cerebrospinal fluid drainage was reported in only 4 studies,
      • Shi E.
      • Gu T.
      • Yu Y.
      • Yu L.
      • Wang C.
      • Fang Q.
      • et al.
      Early and midterm outcomes of hemiarch replacement combined with stented elephant trunk in the management of acute DeBakey type I aortic dissection: comparison with total arch replacement.
      ,
      • Katayama K.
      • Uchida N.
      • Katayama A.
      • Takahashi S.
      • Takasaki T.
      • Kurosaki T.
      • et al.
      Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease.
      ,
      • Leontyev S.
      • Tsagakis K.
      • Pacini D.
      • Di Bartolomeo R.
      • Mohr F.W.
      • Weiss G.
      • et al.
      Impact of clinical factors and surgical techniques on early outcome of patients treated with frozen elephant trunk technique by using EVITA open stent-graft: results of a multicentre study.
      ,
      • Verhoye J.P.
      • Belhaj Soulami R.
      • Fouquet O.
      • Ruggieri V.G.
      • Kaladji A.
      • Tomasi J.
      • et al.
      Elective frozen elephant trunk procedure using the E-Vita Open Plus prosthesis in 94 patients: a multicentre French registry.
      so we could not determine whether this adjunct was protective. In addition, the relationship between circulatory arrest temperature and spinal cord injury was not evaluated for the reasons stated earlier. In a general sense, it is worth noting that many of the survivors of FET will later go on to have an open thoracoabdominal repair, and such interventions have had good results.
      • Coselli J.S.
      • LeMaire S.A.
      • Preventza O.
      • de la Cruz K.I.
      • Cooley D.A.
      • Price M.D.
      • et al.
      Outcomes of 3309 thoracoabdominal aortic aneurysm repairs.

      Study Limitations

      This meta-analysis study had several limitations. The studies analyzed were observational, with the inherent bias and lack of uniformity in surgical methodology and reporting. Summarizing observational studies presents challenges, including the risk of bias inherent in these designs in a widely heterogeneous literature. We do not have patient-level data, so we are unable to relate risk factors to the outcomes of interest with any certainty. Spinal cord drainage was not reported in the majority of studies. Specific definitions of chronic and acute dissection were also not reported. Most of the studies did not examine permanent and transient events separately, and no information on race or ethnicity was included. The characterization of acute and chronic dissection was based on the criteria used in each study, with no specification as to timing. A variety of devices were used in these studies, from commercially available single-piece endoprostheses to custom-made FET prostheses. In addition, this study did not examine the outcomes of the FET procedure as a single-stage operation versus the first of 2 stages, with intended completion and reintervention at the second stage. Survival beyond the operative period also was not examined because it was reported in only 4 studies.
      Nevertheless, this meta-analysis is of vital importance because FET is becoming more popular in the surgical community. In contrast to the other reviews,
      • Tian D.H.
      • Wan B.
      • Di Eusanio M.
      • Black D.
      • Yan T.D.
      A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery.
      ,
      • Etz C.D.
      • Weigang E.
      • Hartert M.
      • Lonn L.
      • Mestres C.A.
      • Di Bartolomeo R.
      • et al.
      Contemporary spinal cord protection during thoracic and thoracoabdominal aortic surgery and endovascular aortic repair: a position paper of the vascular domain of the European Association for Cardio-Thoracic Surgery.
      our analysis included only total arch repairs, emphasizing that for reporting purposes, proximal arch or hemiarch repair in combination with stent-graft placement in the descending thoracic aorta should not be viewed or reported as an FET procedure because the results could be different.

      Conclusions

      Reports of the effectiveness of any new procedure or device must be interpreted cautiously because results from the specialized centers where these innovations typically are first used may not reflect how the device will perform elsewhere. This meta-analysis is an effort to evaluate mortality and neurologic events associated with this relatively new but increasingly popular procedure. In cases of acute type A aortic dissection, this technique should be performed with caution. In addition, landing zone at T8 or beyond or a stent graft length of 15 cm or more was a significant predictor of SCI. This is of utmost importance, because industry is developing single-graft endoprostheses to treat extensive aortic pathology.

      Conflict of Interest Statement

      Dr Coselli consults for, receives royalties and a departmental educational grant from, and participates in clinical trials for Terumo Aortic ; consults and participates in clinical trials for Medtronic , and WL Gore & Associates; and serves as a co-investigator for CytoSorbents. Dr Coselli's work is partly funded by the Cullen Foundation . Dr Preventza consults for, participates in clinical trials for, and has received travel funds from Medtronic, Inc; serves as a consultant for Terumo Aortic and WL Gore & Associates; and has received travel funds from Cook Medical. Dr LeMaire has served as a consultant for Terumo Aortic and Baxter Healthcare; has served as an Advisory Panel Member for Biom'up and Acer Therapeutics; has served as a principal investigator for clinical studies sponsored by Terumo Aortic and CytoSorbents ; and has served as a co-investigator for clinical studies sponsored by WL Gore & Associates. Dr LeMaire's work is supported in part by the Jimmy and Roberta Howell Professorship in Cardiovascular Surgery at Baylor College of Medicine . All other authors have nothing to disclose with regard to commercial support.
      Hiruni Amarasekara, MS, and Susan Y. Green, MPH, helped evaluate articles and reviewed the final article. Scott Weldon, MA, CMI, FAMI, contributed to the artwork and design of the visual abstract. Stephen N. Palmer, PhD, ELS, contributed to the editing of the article.

      Supplementary Data

      Appendix

      Figure thumbnail fx5
      Figure E1Subgroup analysis: SCI in patients treated with stents 15 cm or greater or spinal coverage T8 or beyond versus patients with 10-cm stent length. In the Forest plot, the estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The subgroup pooled event rates are represented by the middle of the solid red diamonds, with the width of the diamonds representing the 95% CI. The summary pooled event rate is represented by the middle of the solid green diamond with the width of the diamond representing the 95% CI and indicates that 11.6% (95% CI, 6.1-21.1) of the patients with stent length 15 cm or greater or coverage T8 or beyond had a spinal cord ischemic event after FET, compared with 2.5% (95% CI, 1.5-4.0) of the patients with stent length 10 cm (P < .001). Note: For reference 42 (Preventza 2017), the authors provided additional information not included in the publication. Among the 37 patients, the stent lengths used were 10 cm (n = 14), 12.5 cm (n = 1), and 15 cm (n = 22). SCI occurred in 2 patients with 15-cm stents. CI, Confidence interval.
      Figure thumbnail fx6a
      Figure E2Subgroup analysis: Outcomes in patients treated for acute type A dissection versus nonacute type A dissection and aneurysm. For these 2 subgroups, respectively, Forest plots show the post-FET event rates for (A) overall, persistent, or transient stroke (9.3% [95% CI, 4.5-18.5]) vs 6.6% [95% CI, 3.1-13.5], P = .51); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (2.4% [95% CI, 1.3-4.2] vs 5.2% [95% CI, 3.1-8.5], P = .05); and (C) overall, operative, 30-day, or in-hospital mortality (9.2% [95% CI, 6.9-12.4] vs 7.6% [95% CI, 4.9-11.4], P = .46). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The subgroup pooled event rates are represented by the middle of the solid red diamonds, with the width of the diamonds representing the 95% CI. The summary pooled event rate is represented by the middle of the solid green diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.
      Figure thumbnail fx6b
      Figure E2Subgroup analysis: Outcomes in patients treated for acute type A dissection versus nonacute type A dissection and aneurysm. For these 2 subgroups, respectively, Forest plots show the post-FET event rates for (A) overall, persistent, or transient stroke (9.3% [95% CI, 4.5-18.5]) vs 6.6% [95% CI, 3.1-13.5], P = .51); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (2.4% [95% CI, 1.3-4.2] vs 5.2% [95% CI, 3.1-8.5], P = .05); and (C) overall, operative, 30-day, or in-hospital mortality (9.2% [95% CI, 6.9-12.4] vs 7.6% [95% CI, 4.9-11.4], P = .46). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The subgroup pooled event rates are represented by the middle of the solid red diamonds, with the width of the diamonds representing the 95% CI. The summary pooled event rate is represented by the middle of the solid green diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.
      Figure thumbnail fx6c
      Figure E2Subgroup analysis: Outcomes in patients treated for acute type A dissection versus nonacute type A dissection and aneurysm. For these 2 subgroups, respectively, Forest plots show the post-FET event rates for (A) overall, persistent, or transient stroke (9.3% [95% CI, 4.5-18.5]) vs 6.6% [95% CI, 3.1-13.5], P = .51); (B) spinal cord injury, including persistent and transient paralysis, paraplegia, and paraparesis (2.4% [95% CI, 1.3-4.2] vs 5.2% [95% CI, 3.1-8.5], P = .05); and (C) overall, operative, 30-day, or in-hospital mortality (9.2% [95% CI, 6.9-12.4] vs 7.6% [95% CI, 4.9-11.4], P = .46). The estimate of the event rate of each study corresponds to the middle of the blue squares, and the horizontal line through the squares shows the 95% CI. The subgroup pooled event rates are represented by the middle of the solid red diamonds, with the width of the diamonds representing the 95% CI. The summary pooled event rate is represented by the middle of the solid green diamond, with the width of the diamond representing the 95% CI. CI, Confidence interval.

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      Linked Article

      • Commentary: Is it time to thaw the frozen elephant trunk procedure?
        The Journal of Thoracic and Cardiovascular SurgeryVol. 160Issue 1
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          Since its introduction into clinical practice in the late 1990s, the frozen elephant trunk (FET) procedure has become a widely used method of repair for extensive intrathoracic aortic disease that requires replacement of the aortic arch, including acute aortic dissection. In this issue of The Journal of Thoracic and Cardiovascular Surgery, Preventza and colleagues1 present the results of a meta-analysis of more than 3000 patients from 35 studies who had undergone FET procedures, focusing on early mortality and the risks of stroke and spinal cord ischemic injury (SCI).
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      • Commentary: The elephant in the room: Walking the walk and talking the talk after a frozen elephant trunk procedure
        The Journal of Thoracic and Cardiovascular SurgeryVol. 160Issue 1
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          The frozen elephant trunk (FET) operation, initially proposed by Kato and colleagues in 1996,1 involves open reconstruction of the proximal aorta with a conventional Dacron prosthesis and a distally secured self-expanding endovascular prosthesis. FET provides a landing zone for repair of residual distal aortic pathology; however, procedural complexity and the potentially increased risk of neurologic complications along with the lack of available outcomes data may limit widescale implementation.
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