Treatment with cardiac resynchronization therapy was associated with a significant reduction in the risk of HF or death only among internal cardioverter defibrillator-treated patients with a low ( Q1-3 ) S-LVRR score ( hazard ratio = 0.55 ; P < 0.001 ) , but not among those with a higher ( Q4 ) score ( hazard ratio = 1.06 ; P = 0.72 ) .