EWOLUTION Confirms Safety, Efficacy for Real-World Use of Watchman, Even With No Postprocedural Drug Therapy

PARIS, France—Real-world experience with the first-generation Watchman left atrial appendage (LAA) closure device shows particularly high success and safety out to 3 months, even among a minority of patients receiving no post-implant anticoagulation. 

Watchman (Boston Scientific) received the CE Mark for use in Europe in 2012 and was approved by the US Food and Drug Administration in March 2015 as an alternative to warfarin for patients with A-fib. Early commercial success has shown promise, but many have questioned what constitutes the most appropriate postprocedural drug therapy, especially for patients at extremely high bleeding risk.

Among 979 patients who received the device between 2013 and 2015 at one of 47 centers in Europe, Russia, and the Middle East, implant success was 98.5%, reported Martin Bergmann, MD (Asklepios Klinik St. Georg, Hamburg, Germany), who presented 3-month results of the EWOLUTION study today at EuroPCR 2016. Of note, more than a quarter of the population was older than 80 years, and about half had a CHA₂DS₂-VASc score of 5 or higher.  

At 3 months, 16.0% of patients had a significant adverse event, with only 0.5% overall experiencing an unknown or device/procedure-related event that resulted in death or other residual effects.

One-quarter (27%) of patients received no anticoagulation preprocedure, while 6% received nothing after their implant. Dual antiplatelet therapy (DAPT) was the most popular options after a Watchman procedure (59.6%), in line with the guidelines, but 7.1% of patients were put on single antiplatelet therapy, 11.1% on a novel oral anticoagulant (NOAC), and 15.6% on warfarin alone. 

There were no differences in any adverse event rates by postprocedural drug regimen, and although bleeding was lowest with NOACs, “this may be selection bias,” Bergmann said.

Watchman as ‘Routine Practice’

EWOLUTION is the study that “we really needed to make [LAA closure] happen in routine practice,” said Bergmann in a press conference. Given prior hesitance of many physicians to push ahead with Watchman implantation, these results should confirm its safety even among patients who cannot receive the recommended anticoagulation postprocedure. However, he cautions against totally forgoing postprocedural drug therapy unless the patient truly cannot tolerate it. 

Also, 3 months marks the point where, if patients reach this milestone without experiencing an adverse event, then they “can get the benefit the procedure, which is stroke prevention,” Bergmann said. Because so many patients were free from events at 3 months, the data should confirm “this structural heart intervention as a routine procedure for stroke prevention in atrial fibrillation,” he added.

As an aside, Bergmann confirmed that all patients in EWOLUTION were treated with the first-generation Watchman device. After European authorities recalled the latest iteration Watchman FLX last month over embolism concerns, the first-generation implant will be the one physicians will work with “for the near future,” Bergmann concluded.  

Short-term NOAC-Only, No-Aspirin Trial Needed

Discussing the results, Farrel Hellig, MD (Sunninghill and Sunward Park Hospitals, Johannesburg, South Africa), pointed out that the primary aim of LAA closure is to prevent stroke in patients with nonvalvular A-fib at high bleeding risk who need an alternative to anticoagulation. As such, the key evidence required of LAA closure is that it is indeed safe and durable but also associated with a low risk of stroke and reduced bleeding. Uncertainty about the postprocedure drug regimen has been a key challenge for the technology.

For the current registry, Hellig said, results suggest that the correct patients are receiving the device—a full 72% had a contraindication to warfarin. The 3-month data also suggest that the procedure is predictable and safe, and that with appropriate training, the device is being correctly used and sized.

That said, the bleeding rate of 4.1% at 3 months remains a concern, according to Hellig. “We clearly need more time to evaluate bleeding” in these patients, he concluded, noting that many patients would still be taking the recommended periprocedural antiplatelet or antithrombotic regimen at 3 months.

The big question remaining is what drug regimen patients should take postprocedure. From the current data, “it appears acceptable to omit warfarin,” Hellig commented. 

But going forward, he continued, “could postprocedure NOACs be the best option? Can aspirin be omitted in the longer term?” This would be “the ideal,” Hellig said.

What’s needed next is a trial of a NOAC only for a specific period of time, but with no aspirin long-term. “That’s the next study we need to conduct in order to complete the puzzle,” Hellig commented.  

• Bergmann MW. EWOLUTION: 3-months outcome of left atrial appendage closure with the Watchman device in Europe: thrombus at the device, leakage at follow-up, device embolisation, post-procedural drug regimen and impact of center experience data from the prospective 1025 patients EWOLUTION Registry. Presented at: EuroPCR 2016. May 17, 2016. Paris, France.

Disclosures:

• EWOLUTION was funded by Boston Scientific.
• Bergmann reports serving as a consultant for Biosense Webster and Boston Scientific and receiving honorarium from Bayer Pharma AG, Biotronik, Boehringer Ingelheim, Daiichi Sankyo and Eli Lilly, Novartis, and St. Jude Medical.

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