Effect of Beta-Blocker Therapy on Myocardial Perfusion Defects in Thallium-201 Scintigraphy in Patients with Dilated Cardiomyopathy

Abstract

Background: Thebeneficial effects of β-blocker therapy in patients with heart failure have been confirmed. However, the effects of β-blockers on myocardial perfusion defects are unclear. The aim of this study was to evaluate the effect of β-blockers on myocardial perfusion defects estimated by thallium-201 myocardial scintigraphy in patients with dilated cardiomyopathy (DCM) and to investigate the relationships between β-blocker treatment and myocardial damage and cardiac function. Methods:²⁰¹Tl and echocardiography were performed in 37 patients before and after 6 months of β-blocker therapy. Extent score (ES) by ²⁰¹Tl was used to quantitate myocardial perfusion defects before and after treatment. Results: ES was significantly decreased by β-blocker therapy. According to the change in ES, DCM patients were classified into three groups, patients who improved, patients showing no change and patients who deteriorated. In the improvement and no-change groups, β-blocker therapy induced a reduction in left ventricular dimensions and an associated increase in ejection fraction. However, in the deterioration group, left ventricular dimensions and ejection fraction were unchanged. There was a significant relationship between the change in left ventricular dimension at end-diastole and the change in ES. Conclusions: β-Blocker therapy could attenuate myocardial perfusion defects in some patients with DCM. The improvement in left ventricular function associated with β-blocker therapy may be related to the attenuation in myocardial perfusion defects.