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Emerging opportunities for cardiac surgeons within structural heart disease

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      Technological advancements, such as the heart-lung machine, prosthetic valves, intravascular catheters, and stents, have increased treatment options for patients and have created exceptional growth for hospitals and cardiac specialists. Although cardiac surgeons have led much of this innovation, the delivery of these therapies has often been led by other medical specialties as the procedures have become less invasive (Table 1).
      TABLE 1Less-invasive cardiovascular procedures
      Aortic stent grafting
      ASD/PFO closure
      Mitral valvuloplasty for mitral stenosis
      PDA closure
      Alcohol septal ablation
      Peripheral arterial stenting
      Arterial endarterectomy-atherectomy
      Catheter ablation accessory pathways and atrial fibrillation
      Pericardial window
      Portocaval shunting
      Coronary artery balloon annuloplasty and stenting
      ASD, Atrial septal defect; PFO, patent foramen ovale; PDA, patent ductus arteriosus.
      Source: Medtronic, Inc. Interventions for heart valve disease by type, 2003-2010. Cleveland, Ohio: Health Research International, Report #057-1-US-0705-221, Summary Exhibit 2; 2005. p. ES-5. Reprinted with permission of the publisher.
      In 1990, coronary artery bypass grafting (CABG) and percutaneous coronary interventions were performed in approximately equal numbers. Since then, percutaneous coronary intervention volumes have grown considerably, whereas CABG volumes have not (Figure 1).
      Health Care Advisory Board
      Although cardiac surgeons have adapted by focusing on surgical repair and replacement of valves, emerging technologies will force further changes.
      Figure thumbnail gr1
      Figure 1Unbounded business for cardiac providers: Historical profile.
      There is a natural trend to decrease procedural invasiveness to mitigate risks and increase acceptance. The ongoing efforts to treat many cardiovascular diseases less invasively include catheter-based approaches. In fact, catheter-based endoaortic grafting and valve repair techniques are in clinical evaluation and might soon become clinical realities. Cardiac surgeons should take a leading position in the development and delivery of these procedures.

      Emerging Technologies Will Increase Procedural Demand

      In the future, treatment options for patients with cardiovascular disease will include open surgical procedures, minimally invasive surgical intervention, and percutaneous approaches (Figure 2). Patients contraindicated for surgical intervention might be candidates for less-invasive treatments, and less recovery time and risk will encourage earlier intervention. Consequently, the number of patients treated will increase.
      Figure thumbnail gr2
      Figure 2Intervention for heart valve disease: 2006-2010.
      The treatment of heart valve disease is one area affected by procedural evolution. For instance, only a small percentage of symptomatic patients with moderate-to-severe mitral regurgitation currently undergo a corrective procedure (Table 2).

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Singh J.P.
      • Evans J.C.
      • Levy D.
      • et al.
      Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
      • Stewart B.F.
      • Siscovick D.
      • Lind B.K.
      • et al.
      Clinical factors associated with calcific aortic valve disease.
      • Iivanainen A.M.
      • Lindroos M.
      • Tilvis R.
      • et al.
      Natural history of aortic valve stenosis of varying severity in the elderly.
      Although it is debatable whether earlier intervention would affect survival rates, it is reasonable to hypothesize that decreasing mitral regurgitation and the volume load on the ventricle might affect quality of life. A similar argument can be made regarding patients with tricuspid regurgitation, for whom treatment options can almost certainly be improved. Although the adverse effects of chronic volume loading on right ventricular performance are poorly understood, it is worthwhile to consider the potential benefits of less-invasive procedures that would decrease the volume load.
      TABLE 2Estimated structural heart disease opportunity: United States
      Patient populationCurrently treated
      Mitral regurgitation
       Moderate to severe2,300,000

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Singh J.P.
      • Evans J.C.
      • Levy D.
      • et al.
      Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
      48,000
      Includes repair and replacement.

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

       Severe220,000

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Singh J.P.
      • Evans J.C.
      • Levy D.
      • et al.
      Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
      Aortic stenosis
       All grades749,000

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Stewart B.F.
      • Siscovick D.
      • Lind B.K.
      • et al.
      Clinical factors associated with calcific aortic valve disease.
      79,000

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

       Severe125,000
      Estimate published in the Health Research International Report 2005.2 The estimate was derived from 2 sources. The first is an article from Stewart and colleagues4 from the Cardiovascular Health Study. This article estimated the prevalence of aortic stenosis (by age) from a cohort of 5201. This prevalence information was combined with data from Iivanainen and associates5 derived from the Helsinki Aging Study, which allowed an estimation of the percentage of patients with aortic stenosis who have severe stenosis.

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Stewart B.F.
      • Siscovick D.
      • Lind B.K.
      • et al.
      Clinical factors associated with calcific aortic valve disease.
      • Iivanainen A.M.
      • Lindroos M.
      • Tilvis R.
      • et al.
      Natural history of aortic valve stenosis of varying severity in the elderly.
      Tricuspid regurgitation
       Moderate to severe1,600,000
      Estimated from the prevalence percentage cited in the article by Singh and coworkers3 times the percentage of the US population in the particular age group.

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      • Singh J.P.
      • Evans J.C.
      • Levy D.
      • et al.
      Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
      <8000
      Includes repair and replacement.

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      Superscript numbers indicate references.
      low asterisk Includes repair and replacement.
      Estimate published in the Health Research International Report 2005.

      Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

      The estimate was derived from 2 sources. The first is an article from Stewart and colleagues
      • Stewart B.F.
      • Siscovick D.
      • Lind B.K.
      • et al.
      Clinical factors associated with calcific aortic valve disease.
      from the Cardiovascular Health Study. This article estimated the prevalence of aortic stenosis (by age) from a cohort of 5201. This prevalence information was combined with data from Iivanainen and associates
      • Iivanainen A.M.
      • Lindroos M.
      • Tilvis R.
      • et al.
      Natural history of aortic valve stenosis of varying severity in the elderly.
      derived from the Helsinki Aging Study, which allowed an estimation of the percentage of patients with aortic stenosis who have severe stenosis.
      Estimated from the prevalence percentage cited in the article by Singh and coworkers
      • Singh J.P.
      • Evans J.C.
      • Levy D.
      • et al.
      Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
      times the percentage of the US population in the particular age group.
      Although most patients are treated for symptomatic and critical aortic stenosis, less-invasive procedures would be beneficial. In addition, intervention could be extended to patients for whom the risk of surgical intervention is currently prohibitive. Within the realm of heart valve disease, patients with pulmonic valve disease are already benefiting from less-invasive approaches, in particular those patients with congenital heart disease. In terms of decreasing the number of reoperations, the benefit to patients with pulmonic valve disease is very real.
      Other growth opportunities exist beyond the treatment of heart valve disease. For example, less-invasive and catheter-based therapies are currently being investigated for the treatment of aortic disease. Worthy of further investigation is ligation of the left atrial appendage for stroke prevention in patients with atrial fibrillation and patent foramen ovale closure for patients with migraine headaches with aura. Less-invasive approaches to each of these pathologies are currently in clinical trials.
      The point of highlighting the aforementioned opportunities is not to state that all of these patients will be treated with new devices but rather to emphasize that many patients remain underserved. Ultimately, the number of patients treated will be determined by the relative patient benefit and risk. By developing new skills, cardiac surgeons can meet the needs of many of these patients.

      Cardiac Surgeons As Structural Heart Disease Specialists: The New Paradigm

      For the most part, the disease states that cardiac surgeons will treat in the future will remain the same as today. However, it might be useful to group these disease states under the heading of structural heart disease (SHD). This provides a framework for considering all of the conditions that adversely affect the structure and function of the heart and thoracic aorta. Cardiac surgeons can therefore be considered SHD specialists. In this article SHD includes conditions that affect the structure or function of the heart and thoracic aorta. By adopting a new treatment paradigm, cardiac surgeons can maximize their opportunities within the emerging discipline of SHD. As SHD specialists, cardiac surgeons will offer patients a range of treatment options. Future cardiac surgeons will have a hybrid of cardiac surgical and endovascular skills. This concept has already been proved with thoracic aorta stent grafting. Trained cardiac surgeons offer patients both surgical and catheter-based options. This model marks the beginning of an evolution in cardiac surgery.
      Although most cardiac surgeons lack catheter therapy experience, demand is increasing for cardiac surgeons with this expertise. A cardiac surgeon with catheter-based skills is a valuable member of any team, representing the only resource for surgical and catheter-based treatments. Furthermore, cardiac surgeons are encouraged to adopt a multidisciplinary team approach, alleviating many “turf war” issues and improving patient care. A well-functioning multidisciplinary team can provide a thorough evaluation and assessment of treatment options.
      Cardiac surgeons are in a unique position to lead the decision-making and treatment process for a number of reasons. First, cardiac surgeons are most familiar with the relevant anatomy and pathophysiology. Second, cardiac surgeons can deliver the operations that will continue to be important treatment options. Third, cardiac surgeons have the available capacity to perform these procedures. Finally, cardiac surgeons are best suited to handle complications related to these treatments.

      Realizing the Opportunity

      Developing the requisite skills is a formidable challenge. Additional training must be addressed, however, to allow cardiac surgeons to offer the full spectrum of therapies. Cardiac surgery training programs are beginning to emphasize developing some of these skills, but the practicing physician will require a different path to acquire new skills. Therefore there is a need to develop a comprehensive, stepwise training program for practicing cardiac surgeons interested in developing new skills (Table 3). This training program should be primarily instructed by physician peers and should include didactic, virtual, and clinical training. Furthermore, depending on the complexity of the acquired skills, the surgeon in training must be supported with ongoing peer support in the clinical arena.
      TABLE 3Cardiovascular skills training
      Training sectionSpecialtyTargeted skill track
      Endovascular strategiesGeneral endovascularBasic endovascular skills
      Abdominal aortic aneurysm repair
      Thoracic aortic aneurysm repair
      Peripheral endovascularPeripheral endovascular techniques
      Carotid angioplasty and distal protection
      Heart valve surgeryAdvanced valve surgeryComplex mitral repair
      Aortic root surgery
      Minimally invasive cardiac surgeryAdvanced minimally invasive valve surgeryAortic valve surgery
      Mitral valve surgery
      Robotic cardiac surgeryMitral valve surgery
      TECAB surgical techniques
      Catheter-based valve therapiesAorticPrimary replacement
      Redo prosthetic replacement
      MitralAnnuloplasty
      Edge-to-edge repair
      Revascularization strategiesRevascularizationBeating-heart surgery
      PerfusionAdvanced arrested heart technologies
      Expanding the scope of practice
      Cardiac surgery rhythm managementSurgical ablation
      • Concomitant surgical ablation
      • Lone surgical ablation
      Cardiac surgery pacingTransvenous pacing techniques
      Epicardial lead placement techniques
      Septal heart defect managementASD and PFO repairPercutaneous ASD and PFO repair
      Congenital heart strategies
      Source: Medtronic, Inc. TECAB, total endoscopic coronary artery; ASD, atrial septal defect; PFO, patent foramen ovale.
      The daunting charge of additional training must be undertaken by those committed to the future of cardiac surgery, including cardiac surgeons, cardiac surgical societies, and industry. These efforts will redefine the future of cardiac surgery and ensure the best possible treatment of patients with SHD.

      Conclusions

      Although initially posing a challenge to cardiac surgeons, emerging technologies also represent a significant opportunity. Patients with structural heart disease will benefit from multiple treatment options offered by a multidisciplinary team that is led by uniquely skilled cardiac surgeons. Given this new treatment paradigm, the future is promising for both cardiac surgeons and their patients.

      References

        • Health Care Advisory Board
        Future of cardiac surgery. Strategic and investment blueprint. Service Line Innovation Brief–2004. The Advisory Board Company, Washington (DC)2004
      1. Health Research International Report. Report no. 057-1-US-0705-221, ES-5.

        • Singh J.P.
        • Evans J.C.
        • Levy D.
        • et al.
        Prevalence and clinical determinants of mitral, tricuspid, and aortic regurgitation (the Framingham Study).
        Am J Cardiol. 1999; 83: 897-902
        • Stewart B.F.
        • Siscovick D.
        • Lind B.K.
        • et al.
        Clinical factors associated with calcific aortic valve disease.
        J Am Coll Cardiol. 1977; 29: 630-634
        • Iivanainen A.M.
        • Lindroos M.
        • Tilvis R.
        • et al.
        Natural history of aortic valve stenosis of varying severity in the elderly.
        Am J Cardiol. 1996; 78: 97-101