Reassurance on TAVR for Bicuspid Valves

June 11, 2019

Reassurance on the use of transcatheter aortic valve replacement (TAVR) in patients with bicuspid valve stenosis has come from a new large observational dataset.

TAVR has become the established treatment for aortic stenosis in patients at increased surgical risk, and recent trials in patients at low surgical risk have also shown impressive results, with the transcatheter procedure now likely to become standard treatment for aortic stenosis patients of all risks.

However, all the randomized trials of TAVR to date have excluded patients with bicuspid valves, the anatomy of which is thought to be more difficult for the TAVR procedure to accommodate than the more common tricuspid valves.

The current study examined outcomes from 81,822 consecutive patients at high or intermediate surgical risk undergoing TAVR with the current-generation Sapien S3 valve recorded in the Transcatheter Valve Therapy Registry.

Of these, 2726 had bicuspid valves. The study used propensity matching to compare outcomes in the bicuspid vs tricuspid patients and found similar results for 30-day and 1-year mortality.

The stroke rate was higher in patients with bicuspid aortic stenosis at 30 days but did not significantly differ at 1 year between the 2 groups.

There were no significant differences in valve hemodynamics or aortic regurgitation, and both groups had significant and comparable improvement in functional and health status after TAVR.

The study was published online in JAMA on June 11. The results were previously presented earlier this year at the American College of Cardiology Annual Scientific Session.

The authors, led by Raj Makkar, MD, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, explain that about 1% of people are estimated to have bicuspid aortic valves, but because these valves are more prone to early degeneration, they account for up to 50% of patients requiring surgery in the younger population.

"The lack of data regarding use of TAVR in bicuspid anatomy...represents a significant challenge in further expansion of the application of TAVR to younger patients," the authors write.

Even though the current data does not come from randomized studies, "these represent generalized outcomes not restricted to highest-volume or most experienced TAVR centers," they note.

"Until data from randomized clinical trials are available, these registry data may be able to guide clinical practice," they add.

In an accompanying editoral, Colin Barker, MD, Vanderbilt University, Nashville, Tennessee, and Michael Reardon, MD, Houston Methodist Hospital, Texas, write that the new findings reported by Makkar et al are "the best data available for the use of the current-generation valve in patients with bicuspid aortic valve and are encouraging."

To Medscape Medical News, Reardon added: "The current data suggest that bicuspid valves are also a good target for TAVR in selected cases."

He explained that the anatomy of bicuspid valves varies, with some anatomies more suitable for TAVR than others. "The heart team knows what type of anatomy has the best chance of working with TAVR. When they think it is treatable, it tends to be treatable. Patients with bicuspid valves included in this study had been selected by the heart teams for the procedure so they probably had favorable anatomy, but we can't tell that from this data."

He says other characteristics to be factored in when considering TAVR for bicuspid valves are the age of the patient and the size of the aorta.

"We know TAVR works well for patients in their 70s and 80s, but we're not sure what the best option is for younger patients — those under about 60 may be better with surgery as we don't have long-term data on TAVR, but that's the same for tricuspid valves. We just see more younger patients with bicuspid disease," Reardon said.

"Another complicating factor for bicuspids is that the same genetic abnormality can lead to a large aorta, and if we see that on the scan, then surgery may be a better option as we can address that at the same time," he added.

"Many of us are already doing TAVR on bicuspids," Reardon said. "However, this new data is welcome as it supports what is already happening. And there will be clinicians who were cautious about TAVR on bicuspids but may be more comfortable now with this data," he added.

Reardon noted that more data will be become available from several ongoing prospective trials of TAVR in bicuspid valves with independent core labs and clinical events committees.

For the study, the researchers analyzed data on 2691 propensity-score matched pairs of bicuspid and tricuspid aortic stenosis. Patients had a median age of 74 years and a STS-predicted risk of mortality of 4.9% and 5.1%, respectively.

Results showed that all-cause mortality was not significantly different between patients with bicuspid and tricuspid aortic stenosis at 30 days (2.6% vs 2.5%) and at 1 year (10.5% vs 12.0%).

The 30-day stroke rate was significantly higher for bicuspid vs tricuspid aortic stenosis (2.5% vs 1.6%), but by 1 year the difference was not significant (3.4% vs 3.1%).

The risk of procedural complications requiring open heart surgery was significantly higher in the bicuspid vs tricuspid cohort (0.9% vs 0.4%), but Reardon describes the 0.9% rate of surgery in the bicuspid group as "still quite low."

There were no significant differences in valve hemodynamics or in moderate or severe paravalvular leak between the two groups. Functional status and improvement in quality of life were also similar.

Makkar et al conclude that: "Because of the potential for selection bias and the absence of a control group treated surgically for bicuspid stenosis, randomized trials are needed to adequately assess the efficacy and safety of transcatheter aortic valve replacement for bicuspid aortic stenosis."

But Barker and Reardon question whether a randomized trial could be practically conducted. "Some surgeons, most interventionalists, and nearly all patients are likely to prefer and therefore push for TAVR given the data presented in the current study and the randomized trials involving low-risk patients," they write.

They add that future nonrandomized studies will help better understand anatomic selection for bicuspid aortic valve types, appropriate measurements for valve sizing, and best practices for implant techniques.

The Transcatheter Valve Therapy Registry is an initiative of the Society of Thoracic Surgeons and the American College of Cardiology. This research was supported by Edwards Lifesciences. Makkar reported research grants and consulting and speaker fees from Edwards LifeSciences, Abbott, Medtronic, and Boston Scientific during the course of the study. Reardon reported support from Medtronic.

JAMA. Published online June 11, 2019. Abstract, Editorial

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