At 7 years of follow-up after initial enrollment , the cumulative rate of death from any cause among patients with left bundle-branch block was 18 % among patients randomly assigned to CRT-D , as compared with 29 % among those randomly assigned to defibrillator therapy alone ( adjusted hazard ratio in the CRT-D group , 0.59 ; 95 % confidence interval [ CI ] , 0.43 to 0.80 ; P < 0.001 ) .