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Impact of timing on major complications after thoracic endovascular aortic repair for acute type B aortic dissection

Open ArchivePublished:November 01, 2014DOI:https://doi.org/10.1016/j.jtcvs.2014.10.105

      Objective

      Thoracic endovascular aortic repair (TEVAR) has been shown to have survival benefit in patients with complicated type B dissection compared with open surgery or medical therapy. We analyze the impact of timing of intervention from the onset of symptoms to TEVAR, and its relation to complications.

      Methods

      Between 2005 and 2012, we performed 132 TEVARs for acute and subacute (<6 weeks) type B dissection; 186 other patients were managed with medical therapy only. Patients were followed in a clinical registry. Standard univariate and survival methods were used.

      Results

      Of the 132 TEVARs for type B dissection, 70 were performed within 48 hours of presentation (Acute-Early); 44 between 48 hours and 14 days from presentation (Acute-Delayed); and 18 between 14 days and 6 weeks of presentation (Subacute). Demographic characteristics were similar among groups. Severe complications were more common in the Early-Acute and Delayed-Acute patients than in the Subacute patients (P = .04) Retrograde type A dissection tended to be more common in the Acute-Early group. Overall survival was similar among groups.

      Conclusions

      Delayed intervention appears to lower the risk of complications of TEVAR for aortic dissection in patients who are stable enough to wait. Among patients initially managed medically, new TEVAR indications were not uncommon, and such patients must be followed closely.

      CTSNet classification

      Abbreviations and Acronyms:

      FDA (US Food and Drug Administration), INSTEAD trial (Investigation of Stent Grafts in Aortic Dissection trial), TEVAR (thoracic endovascular aortic repair)
      See related commentary on pages S156-7.
      Thoracic endovascular aortic repair (TEVAR) has revolutionized the treatment of thoracic aortic diseases. TEVAR in the current era has become the dominant treatment for descending thoracic aortic aneurysms with appropriate anatomy, after the first commercial device gained US Food and Drug Administration (FDA) approval for this indication in 2005.
      • Bavaria J.E.
      • Appoo J.J.
      • Makaroun M.S.
      • Verter J.
      • Yu Z.F.
      • Mitchell R.S.
      Gore TAG Investigators
      Endovascular stent grafting versus open surgical repair of descending thoracic aortic aneurysms in low-risk patients: a multicenter comparative trial.
      • Makaroun M.S.
      • Dillavou E.D.
      • Kee S.T.
      • Sicard G.
      • Chaikof E.
      • Bavaria J.
      • et al.
      Endovascular treatment of thoracic aortic aneurysms: results of the phase II multicenter trial of the GORE TAG thoracic endoprosthesis.
      Subsequently, TEVAR has been used extensively for treatment of penetrating atherosclerotic ulcers, traumatic transection, and acute, complicated, type B aortic dissection.
      First reported by Nienaber and colleagues,
      • Nienaber C.A.
      • Fattori R.
      • Lund G.
      • Dieckmann C.
      • Wolf W.
      • von Kodolitsch Y.
      • et al.
      Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement.
      Moon and colleagues,
      • Moon M.R.
      • Dake M.D.
      • Pelc L.R.
      • Liddell R.
      • Castro L.J.
      • Mitchell R.S.
      • et al.
      Intravascular stenting of acute experimental type B dissections.
      and Dake and colleagues,
      • Dake M.D.
      • Miller D.C.
      • Semba C.P.
      • Mitchell R.S.
      • Walker P.J.
      • Liddell R.P.
      Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms.
      TEVAR has become the dominant treatment of acute type B dissection complicated by either severe end-organ malperfusion or rupture. Initial studies by Szeto and colleagues
      • Szeto W.Y.
      • McGarvey M.
      • Pochettino A.
      • Moser G.W.
      • Hoboken A.
      • Cornelius K.
      • et al.
      Results of a new surgical paradigm: endovascular repair for acute complicated type B aortic dissection.
      and others
      • Zeeshan A.
      • Woo E.Y.
      • Bavaria J.E.
      • Fairman R.M.
      • Desai N.D.
      • Pochettino A.
      • et al.
      Thoracic endovascular aortic repair for acute complicated type B aortic dissection: superiority relative to conventional open surgical and medical therapy.
      • Verhoye J.P.
      • Miller D.C.
      • Sze D.
      • Dake M.D.
      • Mitchell R.S.
      Complicated acute type B aortic dissection: midterm results of emergency endovascular stent-grafting.
      • Pearce B.J.
      • Passman M.A.
      • Patterson M.A.
      • Taylor S.M.
      • Lecroy C.J.
      • Combs B.R.
      • et al.
      Early outcomes of thoracic endovascular stent-graft repair for acute complicated type B dissection using the Gore TAG endoprosthesis.
      showed a dramatic decrease in early mortality when TEVAR was used in these circumstances versus open surgery. More recently, TEVAR has been proposed to prevent late distal aneurysmal degeneration from descending aortic dissection, by promoting remodeling and false lumen thrombosis. Over time, indications for TEVAR have expanded from the most dire rupture and malperfusion cases, to those with isolated renal malperfusion or severe true lumen compression without overt compromise of the distal organ function. Data from the Investigation of Stent Grafts in Aortic Dissection (INSTEAD) trial suggested that, in terms of late mortality and freedom from aortic events, in uncomplicated type B dissection patients treated within the early chronic period, TEVAR may be superior to medical therapy alone.
      • Nienaber C.A.
      • Rousseau H.
      • Eggebrecht H.
      • Kische S.
      • Fattori R.
      • Rehders T.C.
      • et al.
      Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial.
      • Nienaber C.A.
      • Kische S.
      • Rousseau H.
      • Eggebrecht H.
      • Rehders T.C.
      • Kundt G.
      • et al.
      Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial.
      This strategy, however, exposes the patient to significant early risks, including stroke, paralysis, and retrograde extension of the dissection.
      • Neuhauser B.
      • Greiner A.
      • Jaschke W.
      • Chemelli A.
      • Fraedrich G.
      Serious complications following endovascular thoracic aortic stent-graft repair for type B dissection.
      Anecdotally, these complications are believed to be more frequent in the early period after dissection, when the aorta is acutely inflamed and more vulnerable to mechanical complications. In the current study, we analyze the impact of the timing of intervention, from the onset of dissection symptoms to the TEVAR procedure, on the rate of complications in a group of patients undergoing TEVAR for primary clinical indications, ie, not solely for remodeling.

      Methods

      Patients

      Between 2005 and 2012, there were 317 acute type B dissection admissions at the University of Pennsylvania Health system. Among these, we performed 132 TEVARs within the acute and subacute period (<6 weeks) of type B dissection. We classified the TEVAR patients into those who were stented in: the Acute-Early period (TEVAR within 48 hours of symptom onset); the Acute-Delayed period (TEVAR 48 hours to 2 weeks from symptom onset); and the Subacute period (TEVAR 2-6 weeks after symptom onset). TEVARs performed after 6 weeks from symptom onset were not included in this analysis.
      Rupture seen on computed tomography imaging with hemodynamic compromise was classified as frank rupture; rupture without hemodynamic instability was classified as contained rupture. Severe ongoing pain, despite maximal blood pressure control, was defined as impending rupture. Clinical malperfusion was defined as compromise of flow into distal arterial beds from the dissection process, leading to visceral organ-threatening or limb-threatening ischemia. Single-kidney malperfusion without acute renal failure was not included in this definition. Radiographic malperfusion was defined as either a severely compressed true lumen in the aorta without end-organ or limb compromise or single-kidney malperfusion only.

      Surgical Approach

      Patients were triaged upon referral from emergency departments, either to direct admission to the operating room, for patients with immediate life-threatening complications, or to the intensive-care unit for initial stabilization. The TEVAR team is an interdisciplinary team of cardiac and vascular surgeons, cardiovascular anesthesiologists, neurologists, and radiologists. TEVAR procedures are performed in the hybrid operating room with high-quality fixed fluoroscopy equipment. All dissection TEVARs are performed with intravascular ultrasound to verify wire position in the true lumen. Selected graft sizes are typically within 10% oversizing to the maximal outer dimension of the nondissected aorta in the proximal landing zone.
      Rupture cases have total thoracic aortic coverage from the proximal to the subclavian to the celiac artery origin. Malperfusion cases are typically initially treated with a TEVAR graft 15-20 cm in length, and malperfusion is reassessed angiographically. If the malperfusion persists, the TEVAR is extended down to the celiac artery; if it continues to persist, adjunctive branch-graft stenting is performed. The TEVARs performed in this study were primarily done “off-label,” with devices approved for aneurysm indication in the early era, followed by cases enrolled in FDA Investigation Device Exemption clinical trials assessing TEVAR in acute, complicated, type B dissection. Within the last year of the study, devices approved for dissection were used.

      Data and Statistical Methods

      Patients were followed in a prospectively collected clinical perioperative registry, and long-term outcomes were determined from clinical records and administrative data sources. The institutional review board at the study institution approved the study, and the need for patient consent was waived. Continuous data are presented as median ± standard deviation; categoric variables are given as counts and percentages. For comparison of continuous variables, the Student t test was used. Categoric variables were compared using χ2 analysis or the Fisher exact test, as appropriate. Survival was analyzed using the Kaplan-Meier method and log rank calculations.

      Results

      Among the 132 TEVARs for type B dissection, 70 were performed within 48 hours of presentation (Acute-Early); 44 were performed between 48 hours and 14 days from initial presentation (Acute-Delayed); 18 were performed 14 days to 6 weeks after initial presentation (Subacute). The mean age of the patients was similar among groups. The majority of patients were men with a history of hypertension and frequent smoking. Table 1 shows patient characteristics.
      Table 1Patient demographics and cause of TEVAR intervention
      Acute-Early intervention (N = 70)Acute-Delayed intervention (N = 44)Subacute intervention (N = 18)P value
      %n%n%n
      Patient demographics
       Age (y; mean)63.9SD 12.864.3SD 14.364.1SD 14.8.98
       Sex (male)60.04259.12666.712.61
       Cigarette smoker44.33150.02266.712.13
       Prior CVA8.6613.6616.73.43
       Diabetes12.9920.5911.121
       Hypertension91.46497.743100.018.35
       CKD14.31022.71033.36.61
      Indication for TEVAR intervention
       Frank rupture9.060.000.00.4
       Contained rupture43.33025.01111.12.028
       Impending rupture4.5327.31255.610.0002
       Clinical malperfusion34.32427.31211.12.058
       Rad. malperfusion1.5120.5922.24.1
       Other7.550.000.00.47
      P values are for the Subacute group versus the Acute-Early and Acute-Delayed groups combined. TEVAR, Thoracic endovascular aortic repair; SD, standard deviation; CVA, cerebrovascular accident; CKD, chronic kidney disease; Rad., radiographic.
      Among the TEVARs performed in the Acute-Early group (within 48 hours of symptom onset), more than half were for rupture indications, and the majority of the remaining indications were for clinical malperfusion (Figure 1). Among the Acute-Delayed group, 12 patients (27.3%) had new or worsening clinical malperfusion, of which 6 had worsening renal malperfusion with acute renal failure. A further 23 patients were stented for either ongoing pain/impending rupture (12; 27%) or contained rupture (11; 25%). Nine patients (21%) underwent TEVAR for radiographic malperfusion with severely compressed true lumen without end-organ involvement or isolated single-kidney malperfusion without renal failure (ie, remodeling indications). Among patients in the Subacute group (n = 18), 13 (72%) were stented after readmission for symptoms, or blood pressure control. Among these, 11% had new clinical malperfusion, 56% had impending rupture/persistent pain, and 11% had rupture. A further 22% had radiographic malperfusion and were stented for remodeling indications.
      Figure thumbnail gr1
      Figure 1Thoracic endovascular aortic repair indication according to timing from symptom onset.
      Perioperative details are presented in Table 2. Total coverage of the left subclavian artery, with no residual antegrade flow into that artery, was required in 40%-50% of cases. Among these, 6 patients (9.1%) in the Acute-Early intervention group underwent carotid-subclavian bypass after the TEVAR procedure for ischemic symptoms. In the Acute-Delayed group, 4 patients (9.4%) underwent pre-emptive carotid-subclavian bypass, and a larger proportion of the Subacute patient group (5; 27.3%) underwent carotid-subclavian bypass before the TEVAR procedure. Typically, a median of 2 TEVAR grafts were deployed, for coverage between 253.7 mm and 297.8 mm of total coverage.
      Table 2Periprocedural details
      Procedure detailAcute-Early intervention (N = 70)Acute-Delayed intervention (N = 44)Subacute intervention (N = 18)P value
      %n%n%n
      LSCA coverage40.02845.52050.09.35
      Left carotid subclavian bypass9.1
      For the Subacute group versus the Acute-Early and Acute-Delayed groups combined.
      69.4427.85.017
      Total graft length (cm)253.7(SD 163.6)297.8(SD 113.8)278.4(SD 155.9).88
      Number of stents implanted (median)2(1-4)2(1-4)2(1-5)1
      Vascular complication0.000.000.00.86
      Prosthesis migration0.002.710.00.86
      Intraoperative mortality1.412.310.00.35
      P values are for LSCA bypass performed after thoracic endovascular aortic repair. LSCA, Left subclavian artery; SD, standard deviation.
      For the Subacute group versus the Acute-Early and Acute-Delayed groups combined.
      There were 2 intraoperative deaths, 1 from free aortic rupture that could not be salvaged with TEVAR (Acute-Delayed), and 1 with severe gastrointestinal malperfusion and necrosis with unremitting acidosis and cardiac arrest (Acute-Early). Overall, 6 (8.5%) in-hospital mortalities occurred in the Acute-Early group, 2 (4.5%) in the Acute-Delayed group, and none in the Subacute group; overall P = .26. Permanent paralysis or severe paraparesis and permanent stroke were fairly uncommon in these patients. Retrograde aortic dissection was observed in 6 Acute-Early patients (8.5%), and in 3 Acute-Delayed patients (6.8%). In a single patient in the Subacute group, a retrograde type A dissection occurred, after a repeat TEVAR performed in the subacute period for proximal pseudoaneurysm; the patient had been previously stented in the early-acute period for clinical malperfusion with complex arch anatomy. The overall rate of major complications (death, permanent paralysis, permanent stroke, renal failure, and retrograde dissection) was 27 Acute-Early patients (38.7%), 12 Acute-Delayed patients (27.3%), and 1 Subacute patient (5.6%); P = .04 for all acute versus subacute patients (Table 3). No overall difference was found in late survival among groups (log rank P = .5; Figure 2).
      Table 3Perioperative outcomes
      OutcomeAcute-Early intervention (N = 70)Acute-Delayed intervention (N = 44)Subacute intervention (18)P value
      %n%n%n
      In-hospital mortality8.664.5200.28
      Mortality at 30 d12.796.8300.14
      Any paralysis7.054.5211.121
      Paralysis (permanent)1.412.215.61.6
      Any stroke5.644.6200.68
      Stroke (permanent)1.412.31001
      New renal failure8.566.8300.5
      Retrograde type A dissection8.566.830
      Retrograde Type A dissection occurred in a repeat TEVAR performed in the subacute period for a proximal type 1 endoleak in a patient previously stented for clinical malperfusion with complex arch anatomy. This was excluded, as it was from a repeat TEVAR procedure.
      0.5
      For the Subacute group versus the Acute-Early and Acute-Delayed groups combined.
      Overall major complication38.72727.3125.61.04
      Retrograde Type A dissection occurred in a repeat TEVAR performed in the subacute period for a proximal type 1 endoleak in a patient previously stented for clinical malperfusion with complex arch anatomy. This was excluded, as it was from a repeat TEVAR procedure.
      For the Subacute group versus the Acute-Early and Acute-Delayed groups combined.
      Figure thumbnail gr2
      Figure 2Long-term survival stratified by timing of intervention.

      Discussion

      Treatment with TEVAR for acute, type B, aortic dissections, accompanied by life- or limb-threatening malperfusion or rupture, is well established and is associated with improved outcomes compared with medical or surgical treatment modalities. FDA Investigation Device Exemption studies were recently completed on 2 TEVAR devices that previously were labeled for thoracic aortic aneurysm indications for their use in acute, complicated, type B aortic dissection.

      Bavaria J, Brinkman W, Hughes GC, Khoynezad A, Szeto WY, Azizzadeh A, et al. Outcomes of TEVAR in acute type B aortic dissection: results from the Valiant US-IDE Study. Ann Thorac Surg. (in press).

      W.L. Gore and Associates. Evaluation of the GORE Conformable TAG® Thoracic Endoprosthesis for treatment of acute complicated type B aortic dissection. Available at: http://clinicaltrials.gov/ct2/show/study/NCT00908388?sect=X870156. Accessed September 14, 2014.

      Based on these studies, these grafts were approved for treatment of all descending thoracic aortic dissections—complicated or uncomplicated and acute or chronic.
      Among patients with uncomplicated dissections who are managed medically, there is a 15% to 30%, 5-year mortality rate, predominantly from late aortic complications.
      • Fattori R.
      • Montgomery D.
      • Lovato L.
      • Kische S.
      • Di Eusanio M.
      • Ince H.
      • et al.
      Survival after endovascular therapy in patients with type B aortic dissection: a report from the International Registry of Acute Aortic Dissection (IRAD).
      TEVAR has been proposed as a means to prevent these late complications, via positive remodeling of the aorta. This goal is accomplished by covering the primary entry tear and thrombosing at least the covered portion of the false lumen, which may prevent late dilatation.
      Nienaber and colleagues
      • Nienaber C.A.
      • Kische S.
      • Rousseau H.
      • Eggebrecht H.
      • Rehders T.C.
      • Kundt G.
      • et al.
      Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial.
      recently reported results of the INSTEAD trial, in which patients with de novo type B dissection were randomized either to TEVAR, with the first-generation Talent TEVAR graft (Medtronic, Inc, Minneapolis, Minn) plus optimal medical therapy, or to optimal medical therapy alone.
      • Nienaber C.A.
      • Kische S.
      • Rousseau H.
      • Eggebrecht H.
      • Rehders T.C.
      • Kundt G.
      • et al.
      Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial.
      The early results of this study showed improved remodeling of the aorta at the potential cost of elevated early clinical complications. At 5 years, event-free survival was better in the TEVAR arm of the trial, and significant interest has evolved in performing TEVAR for this indication.
      • Nienaber C.A.
      • Rousseau H.
      • Eggebrecht H.
      • Kische S.
      • Fattori R.
      • Rehders T.C.
      • et al.
      Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial.
      Despite increasing use of TEVAR in acute type B aortic dissection, there is a paucity of data on periprocedural complications and the relative impact of timing of intervention on their occurrence. To date, no clear guidance is available on optimal timing of TEVAR in the uncomplicated acute dissection patient. Earlier intervention is potentially advantageous, as the dissection flap is most pliable and provides the best chance for complete remodeling. This advantage must be balanced with the potential increased risks of damage to the acutely inflamed aorta, by either the wires or the stent-graft, which may predispose the patient to retrograde dissection. In the INSTEAD trial, patients were typically treated at more than 60 days after initial dissection, and the rate of technical complications was very low. The aorta was successfully remodeled in the large majority of cases that were randomized to TEVAR, indicating that even this long after initial dissection, the dissection flap is still mobile, and a proximal seal can still be achieved.
      • Nienaber C.A.
      • Kische S.
      • Rousseau H.
      • Eggebrecht H.
      • Rehders T.C.
      • Kundt G.
      • et al.
      Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial.
      In the current study, we found a relationship between earlier intervention and increased periprocedural complications. Among these were a numerically greater number of deaths, acute kidney injury, neurologic complications, and retrograde dissections in patients who underwent previous interventions. The composite outcome incorporating these meaningful clinical endpoints reached significance. These patients were typically implanted with a stent-graft for clinical reasons, and not solely for aortic remodeling, although this was a more common indication in the subacute patients. The overall rate of these complications in the earlier intervention phases warrants close examination, as they provide guidance regarding potential risks associated with early TEVAR for type B dissection. As many patients in the Delayed-Acute and Subacute groups developed new Early-Acute type indications, acuity and complication rates in these groups are likely overestimated; thus, we would expect elective TEVAR for solely remodeling purposes to have even lower complication rates. This effect may be more pronounced in the Acute-Early group, who were more frequently patients with immediate life-threatening complications from type B dissection.
      The development of new TEVAR indications in the initially medically managed subgroups (Acute-Delayed and Subacute) provides new insight into the fate of medically managed type B dissection patients, and stresses the importance of routine follow-up and close surveillance. In the later years of the study, we developed a process at our center for early telephone follow-up by a nurse navigator, an approach that has helped identify patients with evolving dissection-related problems before an aortic catastrophe occurred.
      Retrograde dissection was observed in 9 of 132 patients (6.8%) in this study. This rate is similar to that of retrograde dissection observed in the preapproval acute, complicated, dissection trials using the Valiant Captivia stent graft (Medtronic, Inc, Minneapolis, Minn) (2 of 50; 5% at 1 year) and the conformable GORE TAG thoracic endoprosthesis device (W. L. Gore & Associates, Inc, Flagstaff, Ariz) (5 of 50; 10% at 1 year). In our study, 2 retrograde dissections occurred more than 1 year after implant, and the 1-year rate of retrograde dissection was 7 of 132 (5.5%). Given that this was an “all-comers” series, patients with poor proximal landing-zone features, such as thrombus/intramural hematoma or severe angulation, were included; these patients would have been excluded from the FDA studies. We only included patients with true retrograde dissection in this study, ie, situations in which the stent graft caused the primary aortic tear.
      In summary, earlier intervention with TEVAR is associated with increased postprocedural complications, and the risk of these complications diminished over time, even when the TEVAR was performed for new life-threating indications. Our practice has developed an approach of waiting 2 weeks or longer to perform TEVAR in patients, if it is solely for remodeling purposes. The safety of delayed TEVAR for remodeling purposes warrants further investigation, with multicenter randomized clinical trials.

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      1. Bavaria J, Brinkman W, Hughes GC, Khoynezad A, Szeto WY, Azizzadeh A, et al. Outcomes of TEVAR in acute type B aortic dissection: results from the Valiant US-IDE Study. Ann Thorac Surg. (in press).

      2. W.L. Gore and Associates. Evaluation of the GORE Conformable TAG® Thoracic Endoprosthesis for treatment of acute complicated type B aortic dissection. Available at: http://clinicaltrials.gov/ct2/show/study/NCT00908388?sect=X870156. Accessed September 14, 2014.

        • Fattori R.
        • Montgomery D.
        • Lovato L.
        • Kische S.
        • Di Eusanio M.
        • Ince H.
        • et al.
        Survival after endovascular therapy in patients with type B aortic dissection: a report from the International Registry of Acute Aortic Dissection (IRAD).
        JACC Cardiovasc Interv. 2013; 6: 876-882