TAVR: A Fellow’s Perspective

Feb 14, 2017

Cardiology Interventions

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Keeping up with the progress in the structural field of interventional cardiology can be difficult for fellows in training (FIT), as the field has quickly expanded over the past decade due to promising results observed in clinical trials related to transcatheter aortic valve replacement (TAVR). For a long time, the management of symptomatic severe aortic stenosis (AS) was limited to surgical aortic valve replacement (SAVR), and was what most FITs were taught in medical school. However, with the first successful TAVR performed by Cribier et al. in 2002, this has started to change.1 The first large clinical trial evaluating TAVR was the PARTNER Trial in 2010, which revealed a survival benefit of TAVR with the SAPIEN valve in inoperable patients compared with medical therapy, though at the cost of a higher incidence of stroke and vascular complications.2 A similar result was observed in the non-randomized, prospective US CoreValve Extreme Risk Pivotal Trial presented in 2014, which reported the results of the self-expanding CoreValve.3 These were followed by three major trials: PARTNER IA revealing comparable survival with TAVR (SAPIEN) and SAVR in high surgical risk patients4; CoreValve High Risk showing superior survival with TAVR than with SAVR in high-risk patients5; and, most recently, PARTNER 2A revealing similar survival with TAVR and SAVR in intermediate-risk patients,6 with a subgroup analysis suggesting better outcomes in those patients who underwent transfemoral (TF) TAVR.7 These trials also have shown a decrease in complication rates with TAVR: the increased rates of stroke observed in the PARTNER I trial with TAVR, for example, have not been seen in subsequent studies.

All this has led to U.S. Food and Drug Administration approval of two transcatheter heart valves (THV): the balloon expandable SAPIEN valve, that can be deployed via retrograde or anterograde access; and the self-expandable Nitinol-based CoreValve that is deployed with a retrograde approach. Clinical trials are underway to evaluate TAVR in low surgical risk patients and the use of other, newer generation THV, including the Portico, Direct Flow and Lotus,8 which are likely to be available in the near future.

Reports from The STS/ACC TVT Registry will also be important to understanding outcomes after TAVR in the community outside clinical trials, as well as the long-term durability of THV beyond of 5 years.9-12 To date, registry data have provided good evidence in different risk populations, but also have served to validate new THV generations with decreased delivery system size and unique design changes. For example, the SAPIEN 3 is the latest generation of balloon-expandable valves that allows TF access in a larger number of patients and has an outer skirt to decrease the incidence of paravalvular leak. Operators have also developed less invasive strategies, such as the minimalist TF-TAVR, performed under conscious sedation and transthoracic echocardiogram guidance.13,14 If femoral arterial access is not possible, alternative access sites such as transapical, transaortic, subclavian, transcarotid,15 and more recently, transcaval approach (creating a temporary fistula between the inferior vena cava and descending aorta),16 can all be used.

It comes as no surprise that positive outcomes have resulted in an increased number of TAVRs in multiple institutions. Thus, as FITs, especially those training in interventional cardiology, we need to prepare for our future role in the “heart team” in helping identify and risk stratify candidate patients for this technique and understand the difference between available THV (e.g., balloon vs. self-expandable). We must also be prepared to address some of the complications related to this procedure such as paravalvular leak,17-22 stroke,2-5 vascular complications,2,4,5 acute renal failure, and conduction disturbances requiring permanent pacemaker implantations.23,24 Furthermore, while the rapid implementation of TAVR is encouraging, as clinicians we need to understand some of the limitations of this technique. For example: what is its use in the management of patients with bicuspid aortic valves, and aortic regurgitation? What effect will recent reports of subclinical leaflet thrombosis observed in some THV25 have on future recommendations of anticoagulation or antiplatelet therapy in TAVR patients?

Academic institutions with specialized structural heart centers must continue to lead the structural heart field. Managing complex cases, complications and other emerging percutaneous interventions such as the MitraClip26 and transcatheter mitral valve replacement27 have to be in the armamentarium of all FITs. This is an exciting time for FITs, with a growing number of interventions and more treatment options for our patients. I am excited to see what will happen in the future.

References

  1. Cribier A, Eltchaninoff H, Bash A, et al. Circulation 2002;106:3006-8.
  2. Leon MB, Smith CR, Mack M, et al. N Engl J Med 2010;363:1597-1607.
  3. Popma JJ, Adams DH, Reardon MJ, et al. J Am Coll Cardiol 
  4. 2014;63:1972-81.
  5. Smith CR, Leon MB, Mack MJ, et al. N Engl J Med 2011;364:2187-98.
  6. Adams DH, Popma JJ, Reardon MJ, et al. N Engl J Med 2014;370:1790-8.
  7. Leon MB, Smith CR, Mack MJ, et al. N Engl J Med 2016;374:1609-20.
  8. Thourani VH, Kodali S, Makkar RR, et al. Lancet 2016;387:2218-25.
  9. Meredith Am IT, Walters DL, Dumonteil N, et al. J Am Coll Cardiol 2014;64:1339-48.
  10. Toggweiler S, Humphries KH, Lee M, et al. J Am Coll Cardiol 2013;61:413-9.
  11. Kapadia SR, Leon MB, Makkar RR, et al. Lancet 2015;385:2485-91.
  12. Duncan A, Ludman P, Banya W, et al. JACC Cardiovasc Interv 2015;8:645-53.
  13. Mack MJ, Leon MB, Smith CR, et al. Lancet 2015;385:2477-84.
  14. Babaliaros V, Devireddy C, Lerakis S, et al. JACC Cardiovasc Interv 2014;7:898-904.
  15. Jensen HA, Condado JF, Devireddy C, et al. J Thorac Cardiovasc Surg 2015;150:833-9.
  16. Thourani VH, Gunter RL, Neravetia S, et al. Ann Thorac Surg 2013;96:1349-57.
  17. Lederman RJ, Babaliaros VC, Greenbaum AB. Catheter Cardiovasc Interv 2015;86:1242-54.
  18. Kodali SK, Williams MR, Smith CR, et al. N Engl J Med 2012;366:1686-95.
  19. Tamburino C, Capodanno D, Ramondo A, et al. Circulation 2011;123:299-308.
  20. Koos R, Altiok E, Mahnken AH, et al. Int J Cardiol 2012;158:353-8.
  21. Detaint D, Lepage L, Himbert D, et al. JACC Cardiovasc Interv 2009;2:821-7.
  22. Schultz CJ, Tzikas A, Moelker A, et al. Catheter Cardiovasc Interv 2011;78:446-55.
  23. Buzzatti N, Maisano F, Latib A, et al. Eur J Cardiothorac Surg 2013;43:43-50.
  24. Genereux P, Head SJ, Van Mieghem NM, et al. J Am Coll Cardiol 2012;59:2317-26.
  25. Siontis GC, Juni P, Pilgrim T, et al. J Am Coll Cardiol 2014;64:129-40.
  26. Makkar RR, Fontana G, Jilaihawi H, et al. N Engl J Med 2015;373:2015-24.
  27. Feldman T, Kar S, Rinaldi M, et al. J Am Coll Cardiol 2009;54:686-94.
  28. Anyanwu AC, Adams DH. J Am Coll Cardiol 2014;64:1820-4.

Keywords: ACC Publications, Cardiology Interventions, Cardiovascular Diseases, Heart Defects, Congenital, Registries


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