AT EUROPCR 2016

PARIS (FRONTLINE MEDICAL NEWS) Results of the real-world EWOLUTION registry of recipients of the Watchman device for stroke prevention provide reassuring answers to several key questions which have slowed physician uptake of the left atrial appendage closure device, Dr. Martin W. Bergmann said at the annual congress of the European Association of Percutaneous Cardiovascular Interventions.

“EWOLUTION, with more than 1,000 patients, is I think the study that we’ve needed to make this intervention happen in routine practice as a procedure for stroke prevention in atrial fibrillation,” declared Dr. Bergmann of Cardiologicum Hamburg, a large German group practice.

EWOLUTION is a prospective, single-arm, multicenter registry including 1,025 recipients of the first-generation version of the Watchman, a transcatheter device for left atrial appendage closure as a means of stroke prevention in patients with atrial fibrillation (AF). These were high-risk patients: 50% of them had a CHA2DS2-VASc score of 5 or higher, and 72% of participants were deemed unsuitable for warfarin. EWOLUTION was conducted at 47 sites in Europe, the Middle East, and Russia. Dr. Bergmann presented the 3-month outcomes, a key period for device-related complications because protective epithelialization of the device isn’t yet complete. Follow-up will continue at the 1- and 2-year marks.

Among the key findings in the domain of procedural success: The rate of successful device implantation was 98.5%. A complete seal or an echocardiographic color jet of 5 mm or less at the time of implantation was achieved in 99.7% of cases, and this remained the case in 98.9% at 3 months.

With regard to safety, the stroke rate was 0.4%, device embolization occurred in 0.4%, and the pericardial effusion/tamponade rate was 0.7%, all of which are lower rates than in earlier clinical trials.

Just over 4% of patients experienced device-related adverse events with full recovery at the 3-month follow-up. These were mostly bleeding events at the groin access site. More importantly, only 0.5% of patients had device-related serious adverse events that weren’t resolved at 3 months.

“This 0.5% is a major step forward,” Dr. Bergmann said. “This includes all pericardial effusions, all device embolizations, all periprocedural strokes – everything involving the procedure that puts a patient at risk. In fact, that 0.5% risk for left atrial appendage closure with the Watchman is pretty much the same risk as if you refer your patient with AF to an electrophysiologist for pulmonary vein isolation.”

One key question answered by EWOLUTION is, do you need to be an expert in the procedure in order to get excellent results? The answer, Dr. Bergmann said, is emphatically “no.” Interventionalists at the 47 participating sites varied widely in their experience with left atrial appendage occlusion, so investigators divided the sites into quartiles based upon experience and patient volumes contributed to the registry. While cardiologists in the most experienced centers had a significantly higher rate of successful device release on the first try, the most- and least-experienced centers did equally well on the endpoint that really counts: a complete or near-complete seal of the left atrial appendage at follow-up. Complication rates didn’t differ by site experience, either.

Another important practical question that’s been holding up wider adoption of the Watchman concerns how best to handle postimplantation antithrombotic therapy. Here the EWOLUTION registry provides a partial answer: 607 patients were on dual antiplatelet therapy, 113 were on a novel anticoagulant (NOAC), 159 were on warfarin, 67 were on nothing at all, and the rest were on a single antiplatelet agent. And there was no significant difference between any of these groups in the 3-month rates of thrombus on the device, bleeding events, stroke, or other adverse events.

“The main message is there is no difference in serious adverse events between any of the drug regimens. So if you’re in a situation where you can’t give any medication to reduce stroke risk because the bleeding risk is so high, you can go for left atrial appendage closure technology and give them nothing post implant,” according to Dr. Bergmann.

He added that he’d personally try to avoid that strategy: “You want to have some coverage.”

Also noteworthy is that 113 Watchman recipients did well with 3 months of NOAC monotherapy. The appeal of that approach is the short half-life of those agents in the event of a bleeding problem.

Discussant Dr. Farrel Hellig commented that EWOLUTION demonstrates that the Watchman procedure is predictable and safe, with an impressively low complication rate even in inexperienced centers. For that, he added, kudos goes to Boston Scientific, which markets the Watchman, for rolling out an effective physician training program.

“The most important topic to discuss is bleeding, because a bleeding rate of 4.1% at 3 months is certainly not insignificant,” he continued. “It appears, firstly, from EWOLUTION that it’s safe to omit warfarin. I think the most important thing we’d like to know now is could a postprocedure NOAC be the best option, and can aspirin be eliminated in the long term?”

“Is it too early to recommend a NOAC-only for a period of time post procedure? Perhaps. But I think this would be an important next clinical trial: a NOAC-only for a period post procedure with no aspirin to follow. This is the next piece of information we need to complete the puzzle and for left atrial appendage closure to reach its full potential,” according to Dr. Hellig of the University of Cape Town (South Africa).

The EWOLUTION registry is sponsored by Boston Scientific. Dr. Bergmann reported serving as a consultant to Boston Scientific and Biosense Webster and receiving honoraria from more than a half-dozen pharmaceutical and device companies.

bjancin@frontlinemedcom.com

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