Long-Term Clinical Outcomes Following the WATCHMAN Device Use in Medicare Beneficiaries.

Background: Long-term outcomes following left atrial appendage occlusion outside clinical trials and small registries are largely unknown. Collecting these data was a condition of US market authorization of the WATCHMAN device. The aim of this analysis was to evaluate the rates of stroke, bleeding, and death among Medicare beneficiaries following left atrial appendage occlusion implantation during initial commercial availability of the WATCHMAN left atrial appendage occlusion device overall and in important subgroups.

Methods: All Medicare fee-for-service beneficiaries ≥65 years of age who underwent left atrial appendage occlusion from April 1, 2016, to August 31, 2020, were included based on the International Classification of Diseases, Tenth Revision, and Current Procedural Terminology codes. Over a 5-year follow-up period, the cumulative incidence over time of mortality, ischemic stroke, and major bleeding were calculated using the International Classification of Diseases, Tenth Revision, diagnosis codes for the full study cohort and within important prespecified subgroups.

Results: WATCHMAN recipients (n=48 763) were a median of 77 (interquartile range, 72-82) years of age, 42% female, and mostly White (93%). The median CHA₂DS₂VASc score was 4 (interquartile range, 3-5) with prior major bleeding in 42% and prior stroke in 12%. At 5 years, death occurred in 44%, bleeding in 15% (with higher risk early following implantation), and ischemic stroke in 7%. Each of these end points was more common with greater baseline age. Male patients had greater 5-year mortality than female patients (46.9% versus 40.6%), but there was no difference between sexes in the rates of ischemic stroke (6.6% versus 7.5%) or major bleeding (14.9% for both). WATCHMAN recipients with prior ischemic stroke or a major bleeding event were older and frailer; these groups had higher rates of ischemic stroke, major bleeding, and death.

Conclusions: Compared with patients enrolled in the pivotal clinical trials, Medicare beneficiaries undergoing WATCHMAN implantation were older, more female, and had more comorbid conditions. Substantial long-term mortality and major bleeding following WATCHMAN reflect the high-risk nature of the patient population, while the ischemic stroke rate was relatively low (<1.5% per year).