Conference Coverage

The shrinking role of surgical aortic valve replacement


 

EXPERT ANALYSIS FROM THE CARDIOVASCULAR CONFERENCE AT SNOWMASS

By 2020, 75% of all isolated aortic valve replacements will be done as endovascular procedures, Michael J. Mack, MD, predicted at the Annual Cardiovascular Conference at Snowmass.

That’s assuming, hypothetically, that two ongoing randomized trials – PARTNER 3 and EVOLUT R – comparing TAVR (transcatheter aortic valve replacement) and SAVR (surgical aortic valve replacement) in low-surgical-risk patients have positive results. If so, TAVR will be proven noninferior to SAVR, as has already been convincingly shown in randomized trials conducted in high- and intermediate-surgical-risk patients.

Dr. Michael J. Mack of baylor scott and white Bruce Jancin/Frontline Medical News

Dr. Michael J. Mack

And although Dr. Mack is coprincipal investigator of the 1,000-patient PARTNER 3 trial, which has completed enrollment, he emphasized that the data are still blinded and he has no idea how the results are trending. The PARTNER 3 primary outcome – a composite of all-cause mortality, stroke, and rehospitalization 1 year postprocedure – is due to be unveiled at the 2019 annual meeting of the American College of Cardiology.

Several factors are working against universal adoption of TAVR. There are unresolved concerns about TAVR’s durability, its issues with valve thrombosis, and its greater need for new pacemaker implantation relative to SAVR. Those questions are among the issues being addressed in nearly two dozen ongoing or upcoming TAVR trials, said Dr. Mack, director of the cardiovascular service line at Baylor Scott & White Health System, Houston.

Here are the patients Dr. Mack predicts will likely stick with SAVR for the foreseeable future:

  • Younger patients. Many younger, low-surgical-risk patients will be concerned about TAVR valves’ durability and the current higher pacemaker rate.

“We have some idea of what durability is in the surgical population. What we usually quote is 12-15 years. There has been no major signal of early valve deterioration in TAVR, but there aren’t yet a significant number of patients alive for more than 5 years. Be that as it may, no significant concerns yet, but the other shoe hasn’t dropped,” the cardiothoracic surgeon observed.

Both PARTNER 3 and the EVOLUT R low-risk trial will follow participants annually for 10 years, eventually providing a robust, combined 2,000-patient database to assess comparative device durability.

The 30-day rates of permanent pacemaker implantation in TAVR recipients without a preexisting pacemaker is in the 12%-16% range with the newer-generation Evolut R and Sapien 3 valves. The indication is often new-onset left bundle branch block or complete heart block.

“I don’t think the increased pacemaker incidence is a huge problem now, but with the younger population I think it’s going to be more of an issue,” according to Dr. Mack. “It’s one thing to need a pacemaker if you’re 80-85 years old, but it’s totally different in somebody who’s 55 or 65 that has 30-35 years to live. Pacemaker leads are not benign in that population.”

“On the other hand, there is a thought that younger patients have less intrinsic conduction system disease. It may be that they are less prone to needing a new pacemaker afterward,” he added.

TAVR valve leaflet thrombosis is a concern. While a change in transvalvular gradient on echocardiography provides a signal for this complication, the actual diagnosis of valve thrombosis requires four-dimensional CT. Much better data on the true incidence and clinical ramifications of valve thrombosis in both TAVR and SAVR are coming. For example, the PARTNER 3 and EVOLUT R LR trials will each include 400-patient substudies with four-dimensional CT aimed at answering questions about valve thrombosis. The GALILEO trial, involving 1,520 TAVR patients, is designed to determine whether low-dose rivaroxaban prevents valve thrombosis and periprocedural embolization. Results of this randomized trial are due in about a year. Similarly, the 1,509-patient randomized ATLANTIS trial is looking at the effects of apixaban versus warfarin versus dual or single antiplatelet therapy.

If long-term anticoagulation in TAVR patients is found to be beneficial, that may steer some patients toward SAVR, especially if they are physically active or at high bleeding risk.

  • Aortic stenosis patients with a high Syntax score and multivessel coronary artery disease. This group is best served by concomitant SAVR and coronary artery bypass grafting surgery.
  • Patients with low or intermediate surgical risk with multivalve disease. “We know that patients with moderate to severe mitral regurgitation and/or moderate to severe tricuspid regurgitation do not do well after TAVR,” the surgeon said.
  • Rheumatic valve disease patients.
  • Patients who present at a site that offers SAVR only. “There are about 1,150 cardiac surgery programs in the United States and about 560 TAVR programs. There is concern that patients who don’t come in to a center that offers TAVR will not be offered TAVR as an option. I think there’s probably some truth to that,” Dr. Mack said.
  • Patients going to sites without a well-functioning collaborative heart team. “In institutions where surgeons and cardiologists don’t get along, turf is much more of an issue, and surgeons are going to hold on to those patients more closely,” he observed.
  • Patient’s with certain preferences. “All other things being equal, the patient is always going to choose the less invasive option. However, we do see some patients – I think it’s about 1 out of 10 – who express a preference to stay with the tried and true surgery,” according to Dr. Mack.

He reported receiving research grants from Abbott Vascular, Edwards Lifesciences, and Medtronic.

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