Reduced right ventricular ejection fraction and increased mortality in chronic systolic heart failure patients receiving beta-blockers: Insights from the BEST trial

Right ventricular ejection fraction (RVEF) < 20% is an independent predictor of poor outcomes in patients with advanced chronic systolic heart failure (HF). The aim of this study was to examine if the adverse effect of abnormally reduced RVEF varies by the receipt of beta-blockers.In the Beta-Blocker Evaluation of Survival Trial (BEST), 2708 patients with chronic advanced HF and left ventricular ejection fraction < 35%, receiving standard background therapy with renin-angiotensin inhibition, digoxin, and diuretics, were randomized to receive bucindolol or placebo. Of these 2008 had data on baseline RVEF, and 14% (146/1017) and 13% (125/991) of the patients receiving bucindolol and placebo respectively had RVEF < 20%.Among patients in the placebo group, all-cause mortality occurred in 33% and 43% of patients with RVEF ≥ 20% and < 20% respectively (unadjusted hazard ratios {HR}, 1.33; 95% confidence intervals {CI}, 0.99-1.78; p = 0.055 and adjusted HR, 0.99; 95% CI, 0.71-1.37; p = 0.934). Among those receiving bucindolol, all-cause mortality occurred in 28% and 49% of patients with RVEF ≥ 20% and < 20% respectively (unadjusted HR, 2.15; 95% CI, 1.65-2.80; p < 0.001 and adjusted HR, 1.50; 95% CI, 1.08-2.07; p = 0.016). These differences were statistically significant (unadjusted and adjusted p for interaction, 0.016 and 0.053 respectively).In ambulatory patients with chronic advanced systolic HF receiving renin-angiotensin inhibition, digoxin, and diuretics, RVEF < 20% had no intrinsic association with mortality. However, in those receiving additional therapy with bucindolol, RVEF < 20% had a significant independent association with increased risk of mortality.