Michihiro Suwa, MD; Takahide Ito, MD; Yoshiaki Otake, MD; Ayaka Kobashi, MD; Yuzo Hirota, MD; Keishiro Kawamura, MD

Abstract
This study was performed to evaluate whether beta-blocker therapy was effective in patients with nonischemic dilated cardiomyopathy (DCM) and bradyarrhythmias supported by pacemaker implantation. Beta-blocker therapy is useful for some patients with DCM, especially those with rapid heart rate or residual nonfib r o t i c myocardium in the left ventricle, but no data exist on whether beta-blocker therapy is useful in patients with DCM and bradyarrhythmias. The effectiveness of beta-blocker therapy was prospectively evaluated in patients with DCM and bradyarrhythmias supported by pacemaker implantation and compared with those without these arrhythmias. Beta-blocker therapy was started in 63 patients (45 men, 18 women, aged 11 -83 years) with DCM, in whom 7 had bradyarrhythmias and 56 did not. These bradyarrhythmias were atrioventricular block, sick sinus syndrome and atrial fibrillation with slow heart rate. Of the 56 patients without bradyarrhythmias, 42 (75%) (group 1) responded to beta-blocker therapy, but 5 of the 7 with bradyarrhythmias (71%) (group 2) also responded. Left ventricular end-diastolic dimension was reduced (6.5±0.6cm to 5.6±0.5cm; p<0.0001 in group 1; 6.6±0.8cm to 5.5±0.2cm; p<0.02 in group 2) and left ventricular fractional shortening was improved (13±4% to 27±7%; p <0.0001 in group 1; 12±4% to 29±10%; p <0.05, in group 2) to the same degree in both groups. These results indicate that beta-blocker therapy for DCM is effective not only in patients without bradyarrhyth-mias but also in those with bradyarrhythmias supported with pacemaker implantation.
(Jpn Circ J 1998; 62: 765-769)

Key Words: Beta-blocking agents; Bradyarrhythmias; Dilated cardiomyopathy

Mailing address: Michihiro Suwa, MD, The Third Division, Department of Internal Medicine, Osaka Medical College, 2-7, Daigaku-cho, Takatsuki City, Osaka, 569-8686MZ, Japan. E - m a i l : in3028@poh.osaka-med. ac. jp