Measuring Physical Activity With Implanted Cardiac Devices: A Systematic Review

Background-Physical activity is predictive of cardiovascular outcomes in patients with cardiovascular implantable electronic devices, yet it is not regularly assessed in routine care. Current-generation cardiovascular implantable electronic devices, however, continuously monitor patient activity through a built-in accelerometer, which provides new opportunities to remotely assess patient activity, detect changes in clinical status, and incorporate these data in risk stratification models. This review critically examines the literature on device-measured physical activity (D-PA), with a focus on identifying methodological issues that may affect interpretation of study results. Methods and Results-We conducted a systematic review of D-PA studies published from January 1 1995 to December 30 2017, identifying 29 studies meeting inclusion criteria, 5 of which were validation reports. Few technical details about D-PA sensors are reported, and procedures for analyzing and interpreting D-PA data are heterogeneous. Trends in D-PA over time and associations with clinical outcomes were reported by 22 studies, and in 7 studies, D-PA was combined with other device parameters in risk stratification models, demonstrating modest-to-good sensitivity in predicting acute heart failure decompensation, hospitalization, and mortality. Conclusions-Current evidence suggests that D-PA may be useful for assessing physical activity and predicting clinical outcomes in patients with cardiovascular implantable electronic devices when combined with other device parameters. Future work must address challenges related to D-PA data measurement, interpretation, and generalizability to support expanded clinical applications of this technology.