Accelerometer-assessed physical behaviour and the association with clinical outcomes in implantable cardioverter defibrillator recipients: A systematic review

ABSTRACT Background Current implantable cardioverter defibrillator (ICD) devices are equipped with a device-embedded accelerometer capable of capturing physical activity (PA). In contrast, wearable accelerometer-based methods enable the measurement of physical behaviour (PB) which encompasses not only PA but also sleep behaviour, sedentary time and rest-activity patterns. Objective This systematic review evaluates accelerometer-based methods used in patients carrying an ICD or at high risk of sudden cardiac death. Methods Papers were identified via the OVID MEDLINE and OVID EMBASE databases. PB could be assessed using a wearable accelerometer or an embedded accelerometer in the ICD. Results A total of 52 papers were deemed appropriate for this review. Out of these studies, 30 examined device-embedded accelerometry (189.811 patients), 19 examined wearable accelerometry (1.601 patients) and three validated wearable accelerometry against device-embedded accelerometry (106 patients). The main findings were that (i) a low level of PA after implantation of the ICD and (ii) a decline in PA were both associated with an increased risk of mortality, heart failure hospitalisation and appropriate ICD shock. Second, PA was affected by cardiac factors (e.g. onset of atrial fibrillation, ICD shocks) and non-cardiac factors (e.g. seasonal differences, societal factors). Conclusions This review demonstrated the potential of accelerometer-measured PA as marker of clinical deterioration and ventricular arrhythmias. Notwithstanding that the evidence of PB assessed using wearable accelerometry was limited, there seems to be potential for accelerometers to improve early warning systems and facilitate preventative and pro-active strategies.