Rate responsive pacing using cardiac resynchronization therapy in patients with chronotropic incompetence and chronic heart failure

Aims: : Chronotropic incompetence (CI) is a common finding in patients with advanced chronic heart failure (CHF) and is associated with a worse functional capacity. Whether rate responsive pacing with cardiac resynchronization therapy (CRT) would acutely improve exercise performance in patients with advanced CHF and severe CI (<70 age-predicted maximum heart rate) is unknown. Methods and results: : Patients (n 13) with CHF, a CRT device, and severe CI were randomized in a double-blind crossover pilot study to either DDD (control) or DDDR (rate responsive) pacing. Six minutes walk test (6MWT) distance, oxygen consumption at anaerobic threshold (VO2 AT), and maximal oxygen consumption (VO2 max) were measured. One week later, testing was repeated in the alternate pacing mode.Rate responsive pacing commenced with standard settings in only 9 of 13 (69) patients. In these 9 subjects, 6MWT distance improved acutely from 358.5 ± 40.7 to 376.8 ± 24.5 m with DDDR pacing (P< 0.05). VO2 max did not improve with DDDR pacing (14.0 ± 3.2 mL/kg/min) compared with DDD pacing (13.9 ± 3.0 mL/kg/min; P 0.69). VO2 AT tended towards improvement with DDDR pacing (10.8 ± 2.9 mL/kg/min) compared with DDD pacing (9.6 ± 1.8 mL/kg/min; P 0.29). There was a linear relationship between the increase in heart rate at minute 3 during rate responsive pacing and improvement in VO2 AT (r 0.83, P< 0.05). Conclusion: : When rate responsive pacing using a CRT device is achieved in patients with advanced CHF and severe CI, parameters of aerobic exercise performance improve acutely. Routine exercise testing to ensure successful restoration of heart rate response may be beneficial to optimize CRT settings in this patient population. Published on behalf of the European Society of Cardiology. All rights reserved.