RISK FACTORS FOR RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY IN PATIENTS WITH ISCHEMIC AND NONISCHEMIC CARDIOMYOPATHY FROM THE MADIT-CRT STUDY

Abstract

Methods: We evaluated the risk for the primary end point of death or heart failure event, whichever came first, in patients with IHD (n=1046) and NIHD (n=774) who were enrolled in the MADIT-CRT trial . The Cox model for CRT-D vs. ICD-only hazard ratio was used to evaluate treatment efficacy by disease etiology. The contribution of dichotomized risk variables to the treatment effect was investigated including risk factor-by-treatment interactions. Results: Among patients allocated to ICD-only therapy, IHD was associated with a significant 62% (p=0.02) increase in the risk of the primary end point as compared with NIHD. However, CRT-D therapy was associated with a somewhat more favorable response in NIHD patients (Table). Females, patients with diabetes mellitus, and those with LBBB, derived enhanced efficacy from CRT-D therapy in the NIHD subgroup, with significant risk factor-by-treatment interaction, and LBBB was associated with enhanced efficacy in the IHD subgroup (Table). Conclusions: Our findings demonstrate differences in clinical course and response to preventive CRT-D therapy between IHD and NIHD patients enrolled in MADIT-CRT, suggesting that risk assessment in the 2 subgroups should be carried out separately.