Complete left bundle branch block and smaller left atrium are predictors of response to cardiac resynchronization therapy in advanced heart failure

Background: We previously reported that cardiac resynchronization therapy with defibrillator (CRT-D) is not an appropriate rescue strategy in patients with advanced heart failure (HF), especially those dependent on inotrope infusion, and instead early ventricular assist device (VAD) implantation should be considered. Predictors of response to CRT in such populations, however, remain uncertain. Methods and Results: We studied 67 inpatients aged <65 years old with advanced HF, who received CRT-D between 2007 and 2014. Eleven patients (16%) were responders, in whom LVEF improved >10% at 6-month follow up. On logistic regression analysis, LA volume index (LAVI) <43 ml/m² (odds ratio (OR), 36.67; P=0.001) and complete left bundle branch block (CLBBB; OR, 6.663; P=0.032) were significant predictors of response to CRT-D among the baseline variables. Patients with both predictors were associated with improvements in LVEF and plasma B-type natriuretic peptide compared with those with none of these predictors during the 6-month follow up period (P<0.05 for both). VAD-free survival rate was significantly higher in the responders compared with the non-responders during the 2-year study period (86% vs. 52%, P=0.044). Conclusions: CLBBB and smaller LAVI are novel predictors of response in patients with advanced HF receiving CRT-D in real-world practice. Such responders may be better candidates for CRT-D and delay of cardiac replacement therapy.