EXAMINATION OF ACTIVITY RATES IN ADULT PATIENTS, POST-MYOCARDIAL INFACTION WITH WEARABLE CARDIOVERTER DEFIBRILLATORS

Abstract

Background: Wearable cardioverter defibrillators (WCD) are external devices capable of providing monitoring and immediate intervention from sudden cardiac death (SCD). WCDs contain accelerometers, providing data on patient activity levels. The literature indicates a positive relationship among patient activity levels, survival, and quality of life outcomes in cardiac populations (Kramer et al., 2015; Sears, Whited, Koehler, & Gunderson, 2015). However, there is no research to date on post-myocardial infarction patient activity levels while wearing the WCD. Methods: This study derived data from patients prescribed a WCD post myocardial infarction with a suppressed left ventricular ejection fraction (LVEF). Patient wear-time and activity data, captured by the device accelerometer, was used to describe the relationship between wear-time and physical activity, as well as examine influence of different demographic variables, including sex and age, on wear-time and activity levels. Changes in activity over the duration of days of WCD were also examined. Results: A total of 480 patients (70% male), were included in the study. Descriptive analyses indicated a median age of 64 years (range 31-90) and an overall median wear-time of 23.8 hours per day; median activity per day was 5,727.5 steps. Results indicated a negative relationship between patient wear-time and patient activity over the course of 90 days. Patient age significantly predicted activity over the course of 90 days, as well as patient wear-time. Results also indicated significant differences in median steps over 90 days, based on sex. Significant differences in activity over time were detected, with the median number of steps increasing from 3,681.5 during the first week of wear to 6,327.5 during the last week of wear. Conclusion: Physical activity in adults with a WCD is generally modest and improves over the course of the 90-day typical prescription. Improved health status likely accounts for this change. Younger patients and men were more active, but older adults tended to wear the device more each day. These results provide evidence that the accelerometer may allow clinicians to more closely attend to activity level in overall patient management and in specific populations of patients.