Heart failure decompensation and all-cause mortality in relation to percent biventricular pacing in patients with heart failure: is a goal of 100% biventricular pacing necessary?

OBJECTIVES The goal of this analysis was to determine the appropriate biventricular pacing target in patients with heart failure (HF). BACKGROUND Cardiac resynchronization therapy (CRT) decreases the risk of death and HF hospitalization. However, the appropriate amount of biventricular pacing is ill-defined. METHODS Mortality and HF hospitalization data from patients undergoing CRT in 2 trials (CRT RENEWAL [Cardiac Resynchronization Therapy Registry Evaluating Patient Response with RENEWAL Family Devices] and REFLEx [ENDOTAK RELIANCE G Evaluation of Handling and Electrical Performance Study]; n = 1,812) were analyzed in a post-hoc fashion. Subjects were grouped based on percent biventricular pacing quartiles with the use of Kaplan-Meier survival analysis. RESULTS Subjects were age 72 +/- 11 years; 72% were men and 67% had coronary artery disease. Subjects paced 93% to 100% (quartiles 2 to 4) had a 44% reduction in hazard of an event compared with subjects paced 0% to 92% (quartile 1; hazard ratio [HR]: 0.56, p < 0.00001). Subjects paced 98% to 99% (quartile 3) had similar outcomes as subjects paced 93% to 97% (quartile 2; HR: 0.97, p = 0.82). Subjects paced 100% (quartile 4) had similar outcomes as subjects paced 98% to 99% (HR: 0.78, p = 0.17). There was a significant interaction between a history of atrial arrhythmia and percent pacing. Subjects with a history of atrial arrhythmia were more likely to be paced < or =92% (p < 0.001). CONCLUSIONS For CRT patients in this retrospective analysis, the greatest magnitude of benefit was observed with >92% biventricular pacing.