CRT for Prevention of Heart Failure

Abstract

Cumulative data have shown that conventional right ventricular apical (RVA) pacing might induce left ventricular (LV) systolic dysfunction and lead to development of heart failure. Minimizing ventricular pacing in patients with sinus node disease was useful for prevention of atrial fibrillation but effective pacing strategy for heart block remains unknown. Preliminary data suggested that the potential mechanism of adverse effect by RVA pacing on LV function may be due to dyssynchrony induction followed by adverse LV remodeling. Biventricular (Biv) pacing is a standard therapy for patients with LV systolic failure and dyssynchrony defined as prolongation of QRS on ECG. It was then reasonable to postulate Biv pacing may be an effective strategy to maintain synchronous inter- and intra-ventricular and prevent adverse remodeling in the LV. Early randomized study has supported such hypothesis that Biv pacing was effective in improving LV systolic function in patients with impaired LV ejection fraction and heart block. In a recent prospective randomized trial, 177 patients with standard bradycardia indication for pacing and normal ejection fraction were randomized to either pacing modes. The primary endpoints were LV ejection fraction and end-systolic volume after 1 year of pacing. The results showed that Biv pacing was effective in preserving the LV systolic function and preventing LV dilatation when compared to RVA pacing. The implication of this study will be discussed in detail during the presentation.