Progression of heart failure after biventricular pacing: Is there a subgroup of “favorable nonresponders”?

Background Left bundle branch block (LBBB) and dominant R wave in lead V 1 (RV1) post–biventricular pacing (BiVp) are associated with better clinical outcomes. However, some patients continue to deteriorate despite these favorable electrocardiographic changes. Objective We tested the hypothesis that baseline LBBB and post-BiVp RV1 are associated with better cardiac function and clinical outcomes in patients with progressive deterioration in heart failure after BiVp ("clinical nonresponders") than in patients without these electrocardiographic criteria. Methods Consecutive patients with advanced heart failure and BiVp were included. An increase in R-wave amplitude of over 4.5 times the baseline value was defined as RV1. Clinical outcome was survival free of heart transplantation and/or implantation of mechanical circulatory support. Results A total of 179 (100 (56%) with LBBB; 79 (44%) with non-LBBB) patients with advanced heart failure and BiVp were included. Of the 100 patients with LBBB, 67 (67%) developed RV1 (group 1) but 33 (33%) patients did not develop RV1 (group 2). Of the 79 patients with non-LBBB, 49 (62%) developed RV1 (group 3) and the remaining 30 (38%) patients did not develop RV1 (group 4). Changes in left ventricular ejection fraction and left ventricular end-systolic volume index were not significant in group 1, but deteriorated in the other groups ( P P Conclusion Despite progressive deterioration in heart failure, patients with LBBB and RV1 post-BiVp demonstrate more stable cardiac function and more favorable clinical outcomes than did patients with non-LBBB with or without RV1 post-BiVp.