SAN FRANCISCO – A second-generation percutaneous valve, one that is fully repositionable and retrievable before deployment, used in the treatment of patients with symptomatic and severe aortic stenosis significantly improves the mean aortic-valve pressure gradient.

The transcatheter aortic-valve replacement (TAVR) device (Lotus, Boston Scientific) is designed to help physicians improve control when positioning the replacement valve in the aorta and to reduce the risk of paravalvular regurgitation that can occur following these procedures.

"At 30 days, there was only one patient who was characterized as having moderate or severe aortic regurgitation," lead investigator Dr Ian Meredith (Monash Medical Center, Melbourne, Australia) said when presenting in the results of the REPRISE II study. "This was due to a paravalvular leak. The vast majority of patients had absolutely nothing or only trivial aortic regurgitation."

The Lotus valve has received CE Mark approval for use in Europe but is still investigational in the US.

The REPRISE II Trial

The REPRISE II study, which included 120 patients with aortic stenosis who were considered high risk for surgery, was presented here today at TCT 2013 . The Lotus device differentiates itself from current competitors in that physicians can reposition the valve before deployment as well as resheath and remove it if necessary. In addition, there is an adaptive seal, which Meredith likened to "cling wrap," that is designed to minimize the risk of paravalvular leak.

At 30 days, the mean aortic gradient was 11.5 mm Hg, which was down from 46.4 mm Hg at baseline. The improvement was statistically significant. At baseline, 15.2% of patients were identified as having moderate or severe aortic regurgitation, whereas just 1.0% of patients had moderate aortic regurgitation at 30 days (no severe aortic regurgitation) and 16.8% had mild aortic regurgitation. Five patients died from cardiovascular causes by 30 days and two patients had a disabling stroke.

Meredith said he believes the differentiated second-generation device, which is available is just two sizes right now, 23 mm and 27 mm, will be a valuable addition for the treatment of severe aortic stenosis.

"Size range is a killer at the moment," said Meredith. "We only have two valve sizes, and, of course, speaking to a surgeon, that's a laugh, because surgeons have 2-mm increments for everything [they] do. More valve sizes will be a pretty good next step." Meredith predicts that by the time a US pivotal clinical trial begins, a more flexible catheter design will be available. Right now, he said, the precurved catheter the device is preloaded on requires some understanding in how to manipulate it in the tortuous aorta.

"The key message is that there was no [TAVR-in-TAVR], no ectopic valves, no lost valves, and no dragging valves out through the aorta," said Meredith. "All of that is gone."

Rate of Pacemaker Implantation Is High

Speaking with the media, Meredith said the rate of pacemaker implantation was 28.6%, which is considerably higher than rates observed with the CoreValve (Medtronic) and Sapien (Edwards Lifesciences) devices. Meredith said the implantation of new pacemakers occurred mostly in patients who received an oversized device. Nineteen of the 34 newly implanted pacemakers occurred in patients where the left ventricular outflow tract (LVOT) was stretched by more than 10%, and 14 pacemakers were implanted in patients where the annulus was stretched by more than 10%.

"This is a right-sized valve, not an oversized valve," said Meredith. "You don't oversize this valve. You need the right size because the valve has to expand in order to lock. It's a mechanical mechanism to lock the valve [in place], like a seatbelt." With the addition of more valve sizes, Meredith believes the rate of new pacemaker implantation with the Lotus device will be cut in half.

To heartwire , Dr Cindy Grines (Detroit Medical Center, MI) said one of the problems with TAVR is positioning. In some instances, valves can cover the coronary ostia, which results in ischemic outcomes. In some cases, the valves can embolize, falling down into the ventricle or moving up into the aorta, and then must be retrieved. Some patients even require valve-in-valve procedures—TAVR-in-TAVR as noted by Meredith—to correct aortic insufficiency.

"All of this is very costly, stressful for the operators, and not necessarily very good for the patients, either," said Grines. "So if you have a fully repositionable valve, this makes a huge difference."

Grines added there is evidence suggesting the degree of aortic insufficiency influences patient survival following valve implantation. At present, she noted approximately 22% of patients treated with a CoreValve require a pacemaker. Oversizing the valves in the REPRISE II study likely contributed to the high rate of new pacemakers in this patient population, she said.

Meredith reports grant and research support from Boston Scientific and Medtronic.

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