By Vivek Rajagopal, MD; Meredith Brazil, PA-C; Frances Lockwood, PA-C; Morris Brown, MD; Jim Kauten, MD; Christopher Meduri, MD, MPH
The gold standard for treating valve disease for decades has been cardiac surgery, but transcatheter valve therapies have proved effective in numerous clinic trials. In particular, clinical trials have shown superior outcomes of transcatheter aortic valve replacement (TAVR) in patients considered at high or extremely high risk for cardiac surgery.
Furthermore, over the last several years, transcatheter aortic valve replacement has proved to be noninferior in patients considered at intermediate risk for cardiac surgery. Finally, transcatheter aortic valve replacement is being tested in patients considered low risk for cardiac surgery, and transcatheter mitral and tricuspid valve therapies continue to be developed and tested in clinical trials as well.
TRANSCATHETER AORTIC VALVE REPLACEMENT
Since the first transcatheter aortic valve replacement (TAVR) in 2002 by Alain Cribier(1), numerous clinical trials have shown the safety and efficacy of TAVR in a broad range of patients. The first trial, PARTNER B, randomly assigned patients at prohibitive risk for cardiac surgery to continued medical therapy versus TAVR with a balloon-expandable valve, and TAVR reduced one-year mortality from approximately 50 percent to 30 percent(2).
A similar trial using a self-expanding valve also showed marked reduction in mortality compared to that predicted without treatment(3). In patients considered at high risk for cardiac surgery but operable, the PARTNER A trial showed noninferiority of TAVR to surgical AVR(4). Adding to this, another trial of such patients showed superiority of TAVR to surgical AVR with respect to risk of mortality and stroke(5). For these reasons, TAVR has become the standard of care for patients with aortic stenosis who are considered at high or extreme risk for cardiac surgery.
Furthermore, data continues to accumulate for TAVR in even lower-risk patients. For example, the PARTNER IIA trial randomly assigned “intermediate risk” patients to either TAVR or surgical AVR(6). In the entire trial, TAVR was noninferior to surgery with regard to death or disabling stroke, but in the patients who received the transfemoral-access TAVR (least invasive form of TAVR), the rate of death or disabling stroke was actually lower with TAVR.
Because another trial demonstrated noninferiority of TAVR to surgery, it is clear that TAVR is acceptable, and is in fact approved by the FDA, for these patients(7). In the final phase of this revolution, TAVR is now being compared to surgery in patients considered at very low risk for surgery in two clinical trials of different TAVR valves (Figure 1) (8).
At the Piedmont Heart Institute, we are proud of our team’s contribution to this revolution. Not only have we had excellent experience and outcomes with the TAVR valves tested in these clinical trials, but we are also the only center in the Southeast performing TAVR with cerebral protection in the REFLECT trial, which is aiming to show a reduction in stroke related to TAVR (already infrequent)(9).
TRANSCATHETER MITRAL VALVE REPAIR AND REPLACEMENT
Like those with aortic stenosis, patients with severe mitral valve disease also suffer; they have progressive symptoms of congestive heart failure, with recurrent hospitalizations and increased risk of dying. Although open-heart surgery has been the standard treatment for decades, a substantial proportion of patients are high risk for surgery, and transcatheter valve treatments are playing a greater role in these patients.
The first approved transcatheter mitral valve therapy was the MitraClip, which reduces mitral regurgitation by simulating a surgical technique called the Alfieri stitch, which binds the leaflets together, thereby allowing better co-aptation (Figure 2). In the EVEREST II trial, MitraClip was safe and effective, although not as effective as surgical therapy (10). Nonetheless, the FDA approved the MitraClip for patients considered high risk for surgery because of its safety, and because patients successfully treated with MitraClip had a marked reduction in risk of heart failure hospitalization after therapy.
In patients with heart failure and mitral regurgitation specifically because of poor left ventricular function, the ongoing COAPT trial is investigating the role of MitraClip for this type of mitral regurgitation (“functional MR”). As the leading enroller of patients for COAPT in the Southeast, Piedmont Heart Institute will continue to advance the science of transcatheter mitral valve repair so that we all can take better care of these patients.
We are also excited to advance the science of transcatheter mitral valve replacement (TMVR), which, like TAVR, is a minimally invasive replacement for the mitral valve and will likely be a viable alternative to MitraClip for patients who would benefit from replacement instead of repair. Many TMVR prostheses have shown promise in early feasibility trials around the world (11). In July 2016, our team at the Piedmont Heart Institute performed the first Medtronic Intrepid valve implantation in the United States, and we continue to lead the country in this early trial.
TRANSCATHETER TRICUSPID VALVE REPAIR
Like aortic and mitral valve disease, tricuspid valve disease can also lead to progressive heart failure. Patients with tricuspid valve disease, however, are even less likely to receive cardiac surgery because they tend to have right ventricular dysfunction and/or pulmonary hypertension, which are very high-risk features for surgery.
For these reasons, development of transcatheter tricuspid valve repair is exceedingly important, and several technologies are in either preclinical development or in early human studies (12). The first early feasibility study published was the SCOUT trial, which investigated the TriAlign system (Figure 3); this system allows physicians to put sutures around the tricuspid annulus and bring the sutures together, thereby shrinking tricuspid annular dimensions with reduction in tricuspid regurgitation (13).
The procedure proved safe in all patients, with dramatic improvement in the New York Heart Association (NYHA) class and Minnesota Living with Heart Failure Questionnaire score. The Piedmont Heart Institute enrolled in this trial and is now the most experienced center in the world with this technology. In fact, our team performed the world’s first transcatheter tricuspid valve repair with the TriAlign system in a patient with a pacemaker lead.
Over the next few years, we will continue to see an explosion in development of transcatheter valve therapies. For patients suffering from valve disease, particularly those who are too old, too frail or too sick for cardiac surgery, this revolution offers comfort, options and hope. We at Piedmont Heart Institute are grateful to be part of this, and we are grateful to our patients for allowing us to care for them.
- Cribier A, Eltchaninoff H, Bash A et al. Percutaneous transcatheter implantation of an aortic valve prosthesis for calcific aortic stenosis: first human case description. Circulation 2002;106:3006-8.
- Leon MB, Smith CR, Mack M et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. The New England journal of medicine 2010;363:1597-607.
- Popma JJ, Adams DH, Reardon MJ et al. Transcatheter aortic valve replacement using a self-expanding bioprosthesis in patients with severe aortic stenosis at extreme risk for surgery. Journal of the American College of Cardiology 2014;63:1972-81.
- Smith CR, Leon MB, Mack MJ et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients. The New England journal of medicine 2011;364:2187-98.
- Adams DH, Popma JJ, Reardon MJ et al. Transcatheter aortic-valve replacement with a self-expanding prosthesis. The New England journal of medicine 2014;370:1790-8.
- Leon MB, Smith CR, Mack MJ et al. Transcatheter or Surgical Aortic-Valve Replacement in Intermediate-Risk Patients. The New England journal of medicine 2016;374:1609-20.
- Reardon MJ, Van Mieghem NM, Popma JJ et al. Surgical or Transcatheter Aortic-Valve Replacement in Intermediate-Risk Patients. The New England journal of medicine 2017;376:1321-1331.
- Saji M, Lim DS. Transcatheter Aortic Valve Replacement in Lower Surgical Risk Patients: Review of Major Trials and Future Perspectives. Current cardiology reports 2016;18:103.
- clinicaltrials.gov. The REFLECT Trial: Cerebral Protection to Reduce Cerebral Embolic Lesions After Transcatheter Aortic Valve Implantation. 2017.
- Feldman T, Kar S, Elmariah S et al. Randomized Comparison of Percutaneous Repair and Surgery for Mitral Regurgitation: 5-Year Results of EVEREST II. Journal of the American College of Cardiology 2015;66:2844-54.
- Regueiro A, Granada JF, Dagenais F, Rodes-Cabau J. Transcatheter Mitral Valve Replacement: Insights From Early Clinical Experience and Future Challenges. Journal of the American College of Cardiology 2017;69:2175-2192.
- Rodes-Cabau J, Hahn RT, Latib A et al. Transcatheter Therapies for Treating Tricuspid Regurgitation. Journal of the American College of Cardiology 2016;67:1829-45.
- Hahn RT, Meduri CU, Davidson CJ et al. Early Feasibility Study of a Transcatheter Tricuspid Valve Annuloplasty: SCOUT Trial 30-Day Results. Journal of the American College of Cardiology 2017;69:1795-1806.