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Medicare patients undergoing left atrial appendage (LAA) occlusion with the Watchman device in routine practice tended to be sicker than the trial populations, translating into higher mortality rates in the real world, researchers found.

Among more than 13,000 Medicare beneficiaries with atrial fibrillation (Afib) who underwent LAA closure for stroke prevention, death and readmission rates were:

• Mortality during index admission: 0.2%
• Mortality within 1 year of LAA closure: 7.5%
• 30-day readmissions among those discharged alive: 9.4%
• Readmission within 180 days of discharge for ischemic stroke or transient ischemic attack: 1.2%

That mortality rate is double the 3.6% seen in pooled data from the randomized PROTECT AF and PREVAIL trials.

The difference may have to do with an older patient population (age >65 years), a greater prevalence of comorbidities, and higher CHA₂DS₂-VASc scores, according to Mary Vaughan Sarrazin, PhD, of the University of Iowa College of Medicine, Iowa City, and colleagues, who reported the findings in .

But the real-world cohort's 1.2% rate of stroke readmissions was lower than expected given that mean CHA₂DS₂-VASc was 4.3 in the absence of anticoagulation therapy, Vaughan Sarrazin's group noted.

"Although LAA closure provides an attractive nonpharmacological option for stroke prevention in patients with Afib who are not candidates for long-term anticoagulation therapy, further prospective long-term real-world studies are needed to monitor its safety and efficacy," the authors urged.

Boston Scientific's Watchman, the device used for LAA occlusion in this study, was finally approved by the FDA in 2015 after years of questions about its efficacy.

Operators have reported device-related thrombi after LAA closure and stressed the importance of close clinical monitoring.

Individuals included in the present report had gotten the Watchman implant in 2015-2017 at an average age of 78 (two-thirds were older than 75). The cohort was 87.9% white and 41.3% were women.

"To our knowledge, this is the largest study outside [a] clinical trial to assess the characteristics of patients with Afib undergoing LAA closures and the associated outcomes of mortality, readmissions, and stroke," the authors wrote.

They recalled that the observational studies ASAP and EWOLUTION had also shown higher 1-year mortality (4.6% and 9.8%, respectively) with the Watchman procedure compared to the randomized trials.

The present study was a retrospective analysis limited to Medicare claims data, which lacked several key procedural variables, including a verified cause of death. Moreover, the findings may not be generalizable to younger patients, the investigators acknowledged.

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