Comparison of the therapeutic effects of the beta-blocking agent bisoprolol and the calcium-blocking agent diltiazem in patients with heart failure due to dilated cardiomyopathy

Beta-blocking agents reduce mortality and improve symptoms in patients with dilated cardiomyopathy (DCM). There have been reports that diltiazem, a calcium-blocking agent, is also effective in such patients. We prospectively compared the effects of the beta-blocking agent bisoprolol with those of the calcium-blocking agent diltiazem in 18 patients (11 males and 7 females, age 14 to 68) with DCM. The 18 patients (10 in New York Heart Association functional class III and 8 in class IV) were randomly assigned to 2 groups. Bisoprolol was administered as the first drug in 10 patients and diltiazem was administered in 8. Cross-over to bisoprolol was also performed in 3 patients. At the end of the study, among the 13 patients who had been given bisoprolol, 9 showed a good response (efficacy rate: 69%). In contrast, only 3 of the 8 patients who received diltiazem showed a good response (efficacy rate: 37.5%). Among the patients in NYHA class III, all 7 (100%) who were treated with bisoprolol responded but only 2 of the 4 (50%) treated with diltiazem responded (p<0.05). Among the patients in class IV, 2 of 6 (33%) responded to bisoprolol and 1 of 4 (25%) responded to diltiazem (not significant). These results suggest that diltiazem, like bisoprolol, has a beneficial effect in patients with DCM, with a greater effect in class III patients. However, we conclude that diltiazem should usually be used as a second choice to improve heart failure in DCM, and as the first medication only in those with contraindications to beta-blocking agents.