A RANDOMIZED TRIAL OF BETA-BLOCKADE IN HEART-FAILURE - THE CARDIAC-INSUFFICIENCY BISOPROLOL STUDY (CIBIS)

Background Functional benefit in heart failure due to idiopathic dilat ed cardiomyopathy has been observed after beta-blockade, but improveme nt in survival has not been established in a large-scale randomized tr ial. This was the main objective of the Cardiac Insufficiency Bisoprol ol Study (CIBIS). Methods and Results Six hundred forty-one patients w ith chronic heart failure of various etiologies and a left ventricular ejection fraction of <40% entered this placebo-controlled, randomized , double-blind study. Patients were in New York Heart Association func tional class III (95%) or IV (5%) at inclusion. All received backgroun d diuretic and vasodilator therapy (an angiotensin-converting enzyme i nhibitor in 90% of cases). A total of 320 patients was randomized to b isoprolol and 321 to placebo. Mean follow-up was 1.9 years. Bisoprolol was well tolerated without between group difference in premature trea tment withdrawals (82 on placebo, 75 on bisoprolol; NS). The observed difference in mortality between groups did not reach statistical signi ficance: 67 patients died on placebo, 53 on bisoprolol (P=.22; relativ e risk, 0.80; 95% confidence interval, 0.56 to 1.15). No significant d ifference was observed in sudden death rate (17 on placebo, 15 on biso prolol) or death related to documented ventricular tachycardia or fibr illation (7 on placebo, 4 on bisoprolol). Bisoprolol significantly imp roved the functional status of the patients; fewer patients in the bis oprolol group required hospitalization for cardiac decompensation (90 on placebo versus 61 on bisoprolol, P<.01), and more patients improved by at least one New York Heart Association functional class (48 on pl acebo versus 68 on bisoprolol, P=.04) by the end of follow-up period. Conclusions These results confirm previous trials evidence that a prog ressively increasing dose of beta-blocker in severe heart failure conf ers functional benefit. Subgroup analysis suggested that benefit from beta-blockade therapy was greater for those with nonischemic cardiomyo pathy. However, improvement in survival while on beta-blockade remains to be demonstrated.