Boston Scientific’s Watchman Associated With Low Rate of Stroke in NCDR LAAO Registry

May 15, 2021—Transcatheter left atrial appendage occlusion (LAAO) with the Watchman device (Boston Scientific) was associated with a low rate of stroke at 1 year even among older patients with atrial fibrillation (AFib) who faced a high risk for stroke or bleeding based on their previous health history. The findings offer reassurance that LAAO with the Watchman device is likely effective for the patient population currently receiving it, concluded study investigators of the LAAO Registry.

The LAAO Registry provided 1-year clinical outcomes of treatment with the Watchman transcatheter LAAO for stroke prevention in patients with AFib. The registry is a component of the American College of Cardiology’s (ACC) National Cardiovascular Data Registry (NCDR).

The analysis of the prospective LAAO Registry of patients who received the transcatheter Watchman device found that in practice, the rate of ischemic stroke (the study’s primary endpoint) was generally on par with rates seen in clinical trials leading to the device’s approval.

Matthew J. Price, MD, presented the findings virtually at ACC’s 70th annual scientific session. Dr. Price is director of the cardiac catheterization laboratory at Scripps Clinic in La Jolla, California.

“Based on these data, it seems like we’re doing the right thing,” commented Dr. Price in the ACC press release. “The rate of ischemic stroke was low and supports the clinical effectiveness of transcatheter LAAO as it is currently applied in the United States.”

The Watchman device was approved by the FDA in 2015 to reduce the risk of stroke in patients with AFib that is not caused by problems with the heart valve. It is also used in patients who require an alternative to the long-term use of anticoagulant medications. The Centers for Medicare and Medicaid Services specify that patients receiving the Watchman device should be at high risk for stroke and unable to take long-term oral anticoagulation.

As summarized in the ACC announcement, the investigators analyzed real-world data from more than 36,000 procedures recorded in the LAAO Registry, which includes almost all LAAO procedures performed in the United States. The study includes data from patients who received a Watchman device in 2016, 2017, or 2018.

Dr. Price reported that patients in the registry were on average significantly older and at higher risk than those who were included in clinical trials for the Watchman device. The average age of patients in the registry was 76 years; one-quarter of the patients had previously had a stroke, many were deemed to be at high risk for falls, and approximately 70% had previously experienced clinically relevant bleeding.

According to ACC, after a follow-up period of 1 year, an estimated 1.53% of patients in the registry experiences an ischemic stroke, 8.52% died, and < 0.7% experienced systemic embolism. The rate of stroke was 77% lower than would be predicted by the patients’ CHA2DS2-VASc scores.

“I was actually a bit surprised by the relatively low event rates because the patients are substantially higher risk than those studied in clinical trials,” commented Dr. Price in the ACC announcement. “However, all-cause mortality, as well as bleeding in the weeks following the procedure, were not infrequent—consistent with the comorbidities of this patient population. This underscores the need to individualize one’s approach to stroke prevention so that patients reap the clinical benefit of stroke reduction.”

The ACC summary noted that the study focused only on outcomes from LAAO procedures using the Watchman device. Future studies are planned to assess clinical efficacy at 3 and 4 years.

“By providing more data, I think this study continues to support LAAO in patients who are not suitable for long-term oral anticoagulation,” stated Dr. Price. “The apparently low ischemic stroke event rates also provide support for ongoing clinical trials for LAAO versus oral anticoagulants in patients who are suitable for long-term oral anticoagulation.”

The ACC advised that because it is based on registry data, the study lacked a control group that did not receive the Watchman device for comparison. However, the event rates observed in the study are consistent with those in other registry studies and clinical trials. Dr. Price stated that future research could focus on assessing LAAO in a broader patient population and on outcomes from new devices or techniques for performing the procedure.