Abstract 4859: Effect of Baseline Peak Oxygen Consumption on Clinical Outcomes of Cardiac Resynchronization Therapy: Findings from the COMPANION Exercise Performance Substudy
Cardiac resynchronization therapy (CRT) has been shown to improve clinical outcomes in patients with systolic dysfunction and a wide QRS. Patients (pts) with NYHA class III and IV heart failure (HF) were shown to have a reduction in death and hospitalization with CRT with or without an ICD in the COMPANION trial. 405 patients were enrolled in an Exercise Performance Substudy where cardiopulmonary exercise testing (CPET) with the determination of peak oxygen consumption (VO2) was performed at baseline, 3, and 6 months of post-randomization. At baseline, pts were stratified into two groups: those with Peak VO2 ≥ 16 (Weber Class A and B) and those with Peak VO2 < 16 (Weber Class C and D). All-cause mortality in combination with cause-specific hospitalization (all-cause, cardiac, HF) were compared between treatment groups for each cohort. Hazard ratios and 95% confidence intervals were obtained from covariate adjusted Cox proportional hazard models. Due to the small number of patients a comparison between CRT and OPT on mortality could not be performed in the two peak VO2 groups. The adjusted hazard ratio plots for each outcome are depicted below: In this small substudy of COMPANION, all cohorts demonstrated directionally favorable reductions in the risk of mortality and cause-specific hospitalization with CRT. The risk reduction of death and HF hospitalization with CRT was significant in pts with low baseline peak VO2. This possible discriminatory effect of peak VO2 on outcome with CRT needs to be validated prospectively in a larger cohort of patients.