Abstract Body (Do not enter title and authors here): Background
Implantable cardioverter-defibrillators (ICDs) reduce mortality in patients at risk for sudden cardiac death, but postmarket surveillance is essential for detecting rare device-related safety concerns. We analyzed death-associated adverse events involving Boston Scientific ICDs to identify recurrent patterns of device malfunction.

Methods
We conducted a retrospective analysis of publicly available adverse event reports submitted to the U.S. Food and Drug Administration’s Manufacturer and User Facility Device Experience (MAUDE) database between January 2022 and December 2024. We included all reports explicitly involving Boston Scientific ICDs that the manufacturer or reporter classified as resulting in patient death. Data were reviewed for patient demographics, device type and model, and categorized failure modes based on structured fields and a manual review of narrative descriptions.

Results
A total of 67 death-related events were identified. The most commonly involved models included the Emblem MRI S-ICD (n=14), Reliance 4-Front (n=12), and Autogen (n=5). Device types included dual chamber (30%), subcutaneous (28%), single chamber (28%), and unspecified (14%). Subcutaneous ICDs, designed to reduce transvenous complications, accounted for over a quarter of reported deaths. The most frequent device-related issues were rhythm conversion failure (28%), device integrity problems (24%), battery power failure (9%), and sensing signal abnormalities (7%). The median patient age was 68 years (range: 36–85); 43% were male, 37% female, and 20% unspecified. Narrative review revealed failure clusters involving delayed therapy, abrupt battery depletion, and electrical signal misdetection. In one case, a patient with known battery warning signs experienced sudden asystole and died days later. Another report detailed failure to detect ventricular fibrillation in a patient implanted with an S-ICD.

Conclusion
Deaths associated with Boston Scientific ICDs reveal recurring patterns of electrical and mechanical failure, particularly rhythm conversion failure and device integrity issues. Subcutaneous ICDs appear disproportionately represented. These findings underscore the ongoing importance of real-world surveillance in identifying potential device vulnerabilities and informing both engineering improvements and clinical decision-making.