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 ¡Ý 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 ¡Ý 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.