Clinical Heart and Vascular Center
Hot Topics in Structural Heart Disease
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By Dharam Kumbhani, M.D.
Associate Professor of Internal Medicine
Section Director, Interventional Cardiology
I was pleased to represent UT Southwestern at the 2018 AHA Scientific Sessions. I moderated a session that was jointly hosted by AHA/SCAI titled "Hot Topics in Structural Heart Disease: What's Happening Now? What's Next?" This was a very well-attended session that discussed the landscape for existing structural technologies as well as emerging science and technology in the field. Topics discussed included the current evidence for PFO closure for cryptogenic stroke, recent advances in TAVR, and emerging mitral technologies.
TAVR is rapidly becoming a mature technology, and there are now more than 580 sites in the United States that implant TAVR valves. This past year I was part of the writing committee that updated the operator and institutional requirements for performing these procedures in the U.S. In fact, earlier this year, CMS convened a MEDCAC meeting to hear comments from all stakeholders regarding future requirements for TAVR reimbursement. This meeting was very contentious, and a final decision on the topic is expected early in 2019. This will likely have ramifications for future valve technologies as well.
One of the most exciting advances in this past year has been in the percutaneous mitral space. The COAPT trial showed that transcatheter mitral valve repair using the MitraClip improved outcomes among patients with severe secondary or functional MR, i.e., patients with severe MR and heart failure. On the other hand, the MITRA-FR trial presented and published in 2018 did not show a benefit in a similar patient population, and this session discussed some of the reasons for these differences. In addition, there are some 20 devices currently being tested in various stages of clinical trials for both mitral valve repair and replacement. This is indeed a very exciting space, and we will likely see several advances in the next few years.
We have recently discovered the phenomenon of valve leaflet thrombosis. It is felt that this occurs in about 10 to 15 percent of patients undergoing TAVR implantation. The vast majority of these appear to be subclinical.
I also presented on the optimal antithrombotic regimen for patients post-TAVR. The default has been dual antiplatelet therapy with aspirin and clopidogrel for three to six months, mostly extrapolated from coronary stent data. However, there are several important considerations. A large proportion of patients – nearly 35 to 45 percent– will have either prevalent or incident atrial fibrillation and need concomitant anticoagulation. These are also the patients at the highest risk of bleeding, and so these issues need to be carefully balanced.
In addition, the phenomenon of valve leaflet thrombosis has recently been described. It is felt that this occurs in about 10 to 15 percent of patients undergoing TAVR implantation. The vast majority of these appear to be subclinical. There is tremendous diagnostic and prognostic uncertainty regarding this condition. An important issue to sort out is whether this contributes to accelerated structural valve degeneration. Small studies also indicate that this condition is best treated by anticoagulation, but this needs to be studied further as well. From an investigative standpoint, valve leaflet thrombosis is also a busy area, with several clinical trials ongoing.