Watchman FLX Stays on Track for Stroke Prevention

The newer-generation Watchman device was associated with sustained safety and efficacy out to 2 years when implanted in people at high thromboembolic risk, the PINNACLE FLX IDE study group reported.

Among 400 people who underwent left atrial appendage (LAA) closure with the Watchman FLX, the incidence of ischemic stroke or systemic embolism reached 3.4% at 2 years -- a clear improvement over the performance goal of 8.7% for this prespecified secondary effectiveness endpoint, according to Saibal Kar, MD, of Los Robles Health System in Thousand Oaks, California, and UCLA.

Additionally, the 1.8% incidence of device-related thrombus (DRT) at 2 years reflected the lack of additional DRTs detected after 1 year, Kar told the audience at TVT: The Structural Heart Summit, an annual meeting held by the Cardiovascular Research Foundation and hosted this year in Miami Beach.

For comparison, the classic Watchman LAA occluder had a DRT rate in the 3-4% range, according to Vivek Reddy, MD, of Mount Sinai Health System in New York City, the senior investigator of the PINNACLE group.

Sanjay Kaul, MD, of Cedars-Sinai Medical Center in Los Angeles, called the 2-year PINNACLE FLX data "reassuring."

He also commented that the 3.4% rate of ischemic stroke or systemic embolism here compares favorably with what was observed from the rivaroxaban (Xarelto) arm in the ROCKET-AF trial (where stroke and systemic embolism reached 1.7% per year among atrial fibrillation patients).

Setting the Watchman FLX apart from its predecessor are design features such as more struts, distal tines folded back, and reduced metal exposure.

"The FLX device is without doubt a better device compared to the first generation Watchman for a variety of reasons. The most notable improvements in my opinion are the improved conformability to the LAA, the ability to fully recapture and redeploy the device, and the atraumatic flexible tip that allows safe maneuverability within the LAA," said Pasquale Santangeli, MD, PhD, of the Hospital of the University of Pennsylvania in Philadelphia, who was not involved with the study.

"Hopefully future generations of the device will incorporate additional improvements to further reduce the risk of device thrombus, ideally to zero," he told MedPage Today.

Watchman FLX met primary safety and efficacy endpoints in the 12-month report of the PINNACLE FLX study presented last year.

Study participants were 400 high-risk patients enrolled at 29 U.S. sites. Mean age was 73.8 years, and 35.5% of patients were women. Average CHA₂DS₂-VASc and HAS-BLED scores were 4.2 and 2.0, respectively.

Operators achieved 100% adequate sealing with the Watchman FLX.

Unlike prior Watchman studies, LAA occlusion in PINNACLE FLX was followed by a brief period of direct oral anticoagulant (DOAC) use, not warfarin. By 12 months, most patients were on aspirin alone for their antithrombotic medication.

Reported individual clinical outcomes at 2 years include 9.3% all-cause death, 5.5% cardiovascular death, 3.4% stroke, 0.3% systemic embolism, and 10.1% major bleeding.

The non-randomized nature of the study was a major limitation. "The long-term efficacy and safety of the Watchman FLX is ultimately best evaluated in a randomized trial against a DOAC control arm," Kaul said.

Reddy emphasized that the study protocol had all patients undergo transesophageal echocardiography (TEE) at 45 days and 1 year. Systematic TEE screening for DRTs was not performed after 1 year, he acknowledged.

Not all patients had reached 2-year follow-up in time for the present analysis, he added.

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