Abstract 18222: Pacemaker Quantified Physical Activity Predicts All-Cause Mortality

Background: Cardiac implantable electronic devices provide a unique opportunity to collect precise quantitative longitudinal data with respect to sedentary time and physical activity. We hypothesized that individuals who have greater habitual physical activity based on pacemaker accelerometer measurements would have improved survival compared to those who were sedentary. Methods: Electronic medical records of 62 individuals who underwent de novo pacemaker implantation with a Medtronic EnRhythm™ device at a single center between January 1, 2005 and December 31, 2012 were reviewed. This pacemaker includes an internal accelerometer that measures per minute activity level as above or below a 70 steps/minute threshold and reports the average hours/day activity exceeding this threshold. Accelerometer data obtained from interrogations were abstracted and averaged over a 1 year time period following a 6-month blanking period following implantation. Individuals were categorized as having failed to reach (n=26) or met/exceeded the activity threshold for ≥2 hours/day (n=36). Survival was compared between groups by Kaplan-Meier estimate and Cox proportional hazards models. Results: Cohort average age was 70±12 years. 43.5% had prevalent CAD. Average follow-up time was 5.2±2.1 years. Death occurred in 17 patients (27.4%), 11/26 (42.3%) of the group that failed to achieve the activity threshold for ≥2 hours/day vs. 6 (16.7%) of the group achieving the threshold (p=0.02 by log rank test). Death was over 3 times more likely in the inactive group than the active group [OR 3.11, 95% CI (1.15-8.47), P=0.02]. Following adjustment for sex and CAD, low activity remained a significant risk factor for death [OR 2.99, 95% CI (1.08-8.26), P=0.036]. Conclusions: Pacemaker accelerometer data effectively predicts mortality in pacemaker patients and demonstrates that physical inactivity is associated with reduced survival in this patient population.