Changes in physical activity around the time of major adverse cardiac events in patients with implantable cardioverter-defibrillators

Background With modern implantable cardioverter-defibrillators (ICDs), biometric measures including physical activity have become readily available to physicians. However, despite the increased availability, applications of these data to the clinical setting remain poorly studied. We sought to investigate whether changes in physical activity occur preceding and following cardiac events in patients with ICDs. Methods We reviewed the electronic medical records of patients with ICDs implanted for any indication in 2018 and 2019 in the University of Pennsylvania health system. Patients with ICDs that reported physical activity were included in the study only if they experienced major adverse cardiac event(s) (MACE) that were preceded by at least 6 months without MACE after device implantation. Results Seventy-four of the 827 charts reviewed met inclusion criteria. Baseline activity levels from 6 to 2 months prior to MACE were 2.18-2.21 h/day. In the month prior to MACE, average activity decreased significantly to 2.09 h/day, and subsequently decreased again during the calendar month in which MACE occurred to 1.96 h/day. The lowest average monthly activity levels occurred in the month after MACE, with incremental but non-significant recovery occurring over the subsequent 2 months. Conclusions In a cohort of ICD recipients, a significant decrease in physical activity was observed in the month preceding MACE. To our knowledge, this is the first study that observes time-dependent changes in activity in relation to MACE in a generalizable cohort of ICD recipients. ICD activity monitoring in patients at high risk for MACE may enhance patient care.