Physical Activity in Adults With Wearable Cardioverter Defibrillators in the Post–Myocardial Infarction Period

PURPOSE: Wearable cardioverter defibrillators (WCDs) provide lifesaving defibrillation and are equipped with accelerometers, capable of providing information on patient wear time and physical activity (PA). The purpose of this study was to report on patient PA while wearing a WCD. METHODS: This study derived data from the WCD vendor in patients prescribed WCD post-myocardial infarction (MI) with left ventricular ejection fraction ≤35% in 2016. Using the device accelerometer, the relationship between wear time and PA was examined in a sample of consistent wearers of the WCD. Demographic variables, including sex and age, were examined for impact on wear time and PA. Changes in PA over time were also examined. RESULTS: A total of 1952 patients (71% male) with a median age of 63 yr were included. Descriptive analyses indicated that overall median wear time was 23.8 hr/d; PA was 5568 steps/d. Significant differences in PA over time were identified, with median steps increasing by 67% from the first week of wear to the last week of wear. Patient age and wear time significantly predicted PA; patient age also significantly predicted patient wear time. There were significant differences in median hours of wear time, as well as median steps, based on sex. CONCLUSIONS: PA in adults early after hospital discharge is modest and improves over the course of the 90-d WCD prescription in regular wearers. Improved health status may account for this change. The WCD accelerometer may have value in future clinical care and research by providing a window into daily patient PA levels via remote monitoring.