More than 18 months after the Watchman FLX device was licensed by the Food and Drug Administration for closure of the left atrial appendage (LAA), a prospective analysis of registry data presented at CRT 2022, sponsored by MedStar Heart & Vascular Institute, supports its safely outside of the clinical trial setting.
The data, drawn from the LAA occlusion registry of the National Cardiovascular Data Registry, showed a mortality rate at 45 days of under 1.0%, which was consistent with the acceptably low rate of other adverse events, according to Samir R. Kapadia, MD, chair of cardiovascular medicine at the Cleveland Clinic.
Only 0.5% had a pericardial effusion within 45 days of LAA closure that required intervention. Of those without effusion, 95% had a leak of less than 3 mm and 82% had no leak at all, according to Dr. Kapadia.
Patients enrolled in this analysis, called SURPASS (Surveillance Post Approval Analysis Plan), had undergone left atrial closure with the device from August 2020 to September 2022. There were no exclusion criteria. Ultimately, 2 years of follow-up is planned.
With more than 16,000 patients enrolled, the data on 14,363 patients in this initial 45-day analysis represents “the largest number of Watchman FLX patients evaluated to date,” Dr. Kapadia reported.
Device implantation success 97.5%
The Watchman FLX, which is delivered to the left atrial appendage by a transcatheter approach, was deployed successfully in 97.5% of all 16,048 patients enrolled in the registry. In the 398 cases without successful deployment, the anatomy was not conducive in nearly 70%. Other reasons included failure to meet device-release criteria and change in patient condition.
The outcomes of interest at 45 days were ischemic strokes, systemic emboli, device-related thrombi, device embolization, and bleeding. The primary endpoints at 2 years will be strokes and thrombotic events.
For stroke, the incidence within 45 days was 0.39%. About 25% of the strokes were hemorrhagic and the remainder were ischemic. There was 1 systemic embolism (0.01%), 5 device embolizations (0.03%), and 30 device-related thrombotic events (0.24%). Major bleeding occurred in 508 patients (3.55%).
For context, Dr. Kapadia compared these results to those observed in the PINNACLE FLX trial, which was a nonrandomized but prospective study of the Watchman FLX published about 1 year ago. In PINNACLE FLX, the enrollment was open to patients indicated for oral anticoagulation but who had an appropriate rationale for seeking a nonpharmacological alternative.
Taken from different studies, the outcomes at 45 days should not be construed as a direct comparison, but the similarity of the results can be considered reassuring, according to Dr. Kapadia.
For the composite safety endpoint of all-cause death, ischemic stroke, systemic embolism, or implantation-related events requiring intervention, the rates in SURPASS (0.4%) and PINNACLE FLX (0.5%) were nearly identical. Device leak rates (82.0% vs. 82.8%), stroke rates (0.4% vs. 0.7%), and all-cause death rates (0.9% vs. 0.5%) were also similar.
The similarity of the SURPASS and PINNACLE FLX data provides another level of reassurance.
“The SURPASS registry confirms the safety of the Watchman Flex in the real-world experience when the device is being used by many different operators in a large patient population,” Dr. Kapadia said in an interview.
In “appropriately selected patients,” the SURPASS data confirm that the Watchman FLX device “provides a safe and effective treatment option,” he added.
Relative to the PINNACLE FLX study, which enrolled 400 patients, it is noteworthy that the median age in SURPASS was older (76 vs. 73.8 years), a potential disadvantage in demonstrating comparable safety. The proportion of non-White patients was similar (6.7% vs. 6.3%). SURPASS had a higher proportion of women (40% vs. 35.5%).
The SURPASS data are credible, according to Vivek Y. Reddy, MD, director of cardiac arrhythmia services, Mount Sinai Health System, New York.
“While there are certainly limitations to registry data, I do feel pretty confident that these procedural complication and success rates [in SURPASS] do indeed reflect reality,” said Dr. Reddy, who was a coauthor of the PINNACLE FLX trial. In general, the SURPASS data “mirror most of our clinical experiences in routine clinical practice.”
With these registry data backing up multiple clinical studies, Dr. Reddy concluded, “I do believe that it is fair to say that Watchman-FLX implantation is a quite safe procedure.”
Dr. Kapadia reported no potential conflicts of interest. Dr. Reddy reported a financial relationship with Boston Scientific.