Short term outcome of different lower pacing rates in patients with recently implanted CRT

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac Resynchronization Therapy (CRT) is a well-established treatment for patients with congestive heart failure, impaired ejection fraction and QRS duration more than 130 msec. Around one third of patients remains to be non-responders. Several parameters have been tested aiming at improving the response rate. Purpose We aim at comparing the effect of two bi-ventricularly base pacing rates (DDD 60 Bpm vs DDD 80 Bpm) on the composite endpoint of mortality and hospitalization due to heart failure. Methods We included patients with recently implanted CRT, all patients had LBBB, QRS duration more than 130 msec and ejection fraction less than 35%. Patients were randomized using randomization table into two groups (DDD 60 bpm and DDD 80 bpm). Patients with atrial fibrillation, active coronary artery disease and those who refused to sign a consent were excluded from the study. Patients were followed 3 months after randomization and then every 6 months thereafter. CRT programming was done, the following pacing parameters were standardized for all patients as per protocol: Mode of pacing was set at DDD, sensor was set as passive, VV delay at 0msec, sensed AV delay at 120ms and paced AV delay at 150ms. Dynamic AV and VV delay optimization algorithms were intentionally turned off. Results Fifty-one patients were enrolled, 45 patients were included in the final analysis (one died before the randomization, two patients were excluded due to average heart more than 80 beats/min at the time of randomization and three were lost to follow up). Mean age was 51.67 ± 11.1 years, 23 patients (51.1%) were females. Thirty-seven patients (82.2%) had dilated Cardiomyopathy, 16 patients (35.6%) had New York heart association (NYHA) functional class (FC) III heart failure (HF) and 29 patients (64.4%) had NYHA class IV (ambulant) HF. At baseline, Minnesota living with heart failure questionnaire score was (52.56 ± 14.3), six minutes-walk distance was 242 ± 95.9 meters and EF was 24.6± 7.4%. Patients were followed for mean duration of 23.2 ± 11.5 months. More patients reached the primary endpoint of death or hospitalization due to heart failure in the DDD 80 bpm group [ 3 (13.6%) vs 13 (56.5%), P=0.003]. This was driven mainly by hospitalization due to heart failure. Death was numerically higher in the DDD 80 group but this was not statistically significant [1 (4.5%) vs 4 (17.4%), P=0.18]. Patients in DDD 60 group had significant improvement in the 6MWD, NYHA functional class, EF % and Minnesota living with heart failure score compared to non-significant improvement in the DDD 80 group. (Table 1) Conclusions In CRT recipients, Base pacing rate 60 beats/min shows less incidence of the composite endpoint of mortality and hospitalization due to heart failure and base pacing rate 80 beats/min could potentially be harmful.