Boston Scientific's Watchman Evaluated in Real-World Postapproval Registry

November 2, 2016—Results of the real-world, postapproval experience in the United States of the Watchman device (Boston Scientific Corporation) found high procedural success and low complication rates despite implantations by a large percentage of new operators. The Watchman device was approved by the US Food and Drug Administration (FDA) in March 2015 for left atrial appendage occlusion (LAAC) to reduce the risk of stroke in patients with nonvalvular atrial fibrillation.

Findings from the Watchman United States Postapproval Study, which was funded by Boston Scientific, were reported at TCT 2016, the 28th annual Transcatheter Cardiovascular Therapeutics scientific symposium in Washington, DC. The results were simultaneously published by lead investigator Vivek Y. Reddy, MD, et al in the Journal of the American College of Cardiology.

In the TCT press release, Dr. Reddy commented, “While LAAC avoids the anticoagulant-related lifetime risk of bleeding, implantation of the device can be associated with upfront complications. Thus, enthusiasm for LAAC as a treatment option has been appropriately tempered, particularly as the therapy is introduced into general clinical practice.”

The TCT announcement noted that despite the absence of a formal national prospective clinical registry, the investigators were able to collect procedural data on all LAAC procedures since FDA approval. The Watchman manufacturer, Boston Scientific, required a clinical specialist be present at all cases, and procedure parameters and major complications were collected and reported using a standardized process and forms.

In this multicenter, prospective registry, 3,822 consecutive patients underwent device implantation by 382 operating physicians in the United States. The operators included both those who had previously performed LAAC procedures as part of clinical trials (29%), as well as “naive” operators (71%)—those physicians who had not previously performed any Watchman procedures prior to FDA approval. This latter physician group performed 50% of all procedures in the 3,822-patient cohort.

As summarized in the TCT press release, the procedure was successfully performed in 3,653 of 3,822 patients (95.6%) with an average duration of 50 minutes. The most prevalent complication reported was pericardial effusion requiring intervention in 39 patients (1.02%). The procedure-related stroke rate was 0.08% (n = 3) and the mortality rate was 0.08% (n = 3). There were nine (0.24%) instances of device embolization; six of these required surgical removal, and three were removed percutaneously. All but one of the device embolizations were identified either during the procedure (n = 5) or while the patient was recovering in the hospital (n = 3).

Dr. Reddy concluded, “The data shows that the United States clinical experience with LACC using the Watchman device has been favorable. Since the device was approved by the FDA, the technology has been used in increasing numbers of patients and procedural success rates remain high. In addition, despite a large percentage of previously inexperienced operators performing the implantation procedures, complication rates continue to improve compared to earlier clinical trials.”