Tepid Response to TAVR in Low-risk Patients With Bicuspid Valves

Patrice Wendling

March 29, 2020

The first prospective trial of transcatheter aortic valve replacement (TAVR) in patients at low surgical risk with bicuspid aortic stenosis showed low early rates of death or disabling stroke, but questions remain over whether the benefits outweigh surgery in this highly selected population.

Dr Basel Ramlawi

The primary endpoint of all-cause mortality or disabling stroke at 30 days occurred in 1.3% of 150 patients (1 event each) implanted with a self-expanding valve (CoreValve Evolut R/Evolut PRO , Medtronic) in the single-arm EVOLUT Low Risk Bicuspid Study.

The device success rate was 95.3%. There were no aortic dissections or annular ruptures, one coronary artery obstruction that required conversion to surgery, and two major vascular complications.

Mild aortic regurgitation (AR) occurred in 40.4% of patients, with no moderate or severe AR.

At 30 days, 15.1% of patients required a permanent pacemaker — a rate lower than that reported in the EVOLUT Low Risk Study, noted study author Basel Ramlawi, MD, Valley Health System, Winchester, Virginia.

"TAVR with the Evolut supra-annular, self-expanding valve in low-risk bicuspid patients achieved excellent early results," he said during a virtual presentation at the American College of Cardiology 2020 Scientific Session (ACC.20)/World Congress of Cardiology (WCC).

The US Food and Drug Administration expanded the indication for TAVR to low-risk patients last year, but physicians have been hesitant to refer patients without data on long-term durability.

In addition, patients with bicuspid aortic stenosis have been generally excluded from prior TAVR trials.

"I think this is a green light in terms of having this as a possibility or available to low-risk patients, provided that this is being evaluated by a multispecialty team with all available options on the table," Ramlawi told theheart.org | Medscape Cardiology.

The present study was performed at high-volume, experienced centers that recommended annular sizing and strongly encouraged pre-TAVR balloon dilatation (91.3%). Bicuspid morphology was confirmed by computed tomography.

In addition, there was rigorous adherence to patient selection parameters, Ramlawi said. Of the 222 patients screened, 46 were excluded for anatomic reasons, including tricuspid disease, aortic root dimensions, mean ascending aorta greater than 45 mm, and prohibitive left ventricular outflow tract calcification. Age younger than 60 years and multivessel coronary disease were also key exclusion criteria.

The mean age was 70.3 years and mean Society of Thoracic Surgeons PROM score was 1.4%. Embolic protection was used in 30% of patients.

Ashish Pershad, MD, an interventional cardiologist from Banner - University Medical Center in Phoenix, Arizona, who was not involved in the study, said the study adds to the body of evidence in a small way, but not substantially.

"I do not believe that low-risk patients with bicuspid pathology will, based on this study with 30-day follow-up, suddenly be treated with Evolut R valves," he told theheart.org | Medscape Cardiology.

"It sets the stage for evaluation in a bigger scale, but it doesn't give anybody the green light to do TAVR for low-risk patients with bicuspid valves."

Pershad said he was struck by the rate of nondisabling stroke (3.3%) and the frequent use of post-TAVR balloon dilation (36.9%) and the need to resheath or recapture the Evolut device (32.9%).

"I agree that's one of the beauties of a self-expanding platform, but by the same token there is more frequent need to postdilate," he said. "Look at the risk strategies you're incurring for stroke — you're predilating the valve, then you're repositioning the valve, then you'[re postdilating the valve. So three opportunities for potential disruption of aortic plaque and potential stroke risk."

Moreover, these cases can be "done with surgery with a low mortality of less than 1%, with no paravalvular leak and lower pacemaker rate, no coronary obstruction, and an opportunity to treat the aortic root if there's concomitant pathology, which is fairly common with bicuspid valves," Pershad observed.

During a discussion of the results, panelist Judy Hung, MD, director of echocardiography at Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, questioned which bicuspid patients should reasonably undergo TAVR today, noting reintervention rates were higher with TAVR vs surgery in the recent 5-year PARTNER-2 results.

Fellow panelist David H. Adams, MD, chair of cardiovascular surgery at the Icahn School of Medicine at Mount Sinai Medical Center in New York City, also pushed the point.

"I want to know, today from this data, would you recommend I have a transcatheter valve because I would argue that the death/stroke rate and the permanent pacemaker rate and the mild AR rate is much higher than if I come to you for surgery," Adams said.

"I agree with you, it's a tough call, and I think a lot of it has to do with the patient coming to me and oftentimes I talk them out of TAVR," Ramlawi replied.

Commenting further, he said, "But what this data does show is in patients who do favor this or for whatever other reason — if the anatomical criteria fits and the coronaries are fine, the heights are fine, and the sinuses are okay — this is an option for that patient. There's a lot of social factors and clinical factors that play into this."

In another spirited exchange, Adams said, "I keep hearing these new generations are going to solve aortic regurgitation, but you still have a high rate of mild regurgitation. Did you see any difference between the two valves?"

Ramlawi replied, "We did not do that subgroup analysis, but we do know that with the Evolut PRO skirt around, it does help in terms of reduction of leaking."

"I know, I keep hearing that," Adams quickly interjected. "I want to see that one day."

Valve hemodynamics in the present study were centrally adjudicated by a core echocardiographic laboratory. The mean AV gradient was 7.6 mm Hg and the effective orifice area was 2.3 cm2.

Of special note, valve hemodynamics were similar across Sievers subtypes, with the more technically challenging type 0 valves counterintuitively doing just as well postoperatively and at 30 days, Ramlawi said.

"This study did show — at least in the early feasibility, safety, and efficacy of this valve — that those patients did very well with very good hemodynamics and very good paravalvular leak rates. So that consideration is somewhat alleviated, but it needs to be looked at long-term," he said in an interview.

Most patients had type 1 bicuspid valves and 14 had type 0, with no type 2 valves. Follow-up is planned for 10 years.

The study was sponsored by Medtronic; its personnel performed all statistical analyses and assisted with the graphical display of the data presented. Ramlawi reports receiving research grants and consulting fees from AtriCure, Liva Nova, and Medtronic. Pershad reported no relevant conflicts of interest.

American College of Cardiology 2020 Scientific Session (ACC.20)/World Congress of Cardiology (WCC). Abstract 405-10. Presented March 29, 2020.

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