Activity monitoring in heart failure patients with cardiac resynchronization therapy

Background Cardiac resynchronization therapy (CRT) improves functional capacity in heart failure patients. This study aimed to prospectively analyze long-term device-based monitoring of physical activity in patients undergoing CRT. Methods and Results The Activity Log Index (ALI), calculated by CRT devices, represents the percentage of time when acceleration exceeds a threshold and monitors the physical activity. Data from 178 CRT patients (New York Heart Association III 91%, left ventricular ejection fraction 21±6%, left ventricular end-diastolic diameter 69±9 mm, QRS 159±27 ms, sinus rhythm 81%) were retrieved. The ALI increased from a baseline value of 3.6±2.0 to 11.2±4.6 (p