Effect of β-blockade on regional left ventricular function in patients with dilated cardiomyopathy

It has been reported that β-blockade has beneficial effects on the cardiac function and prognosis of patients with congestive heart failure. However, the mechanism for these effects remained unclear. This study compared the use of an angiotensin-converting enzyme (ACE) inhibitor (enalapril, 2.5 to 5.0 mg/day, or delapril, 15 to 30 mg/day) alone with the effects of β-blockade therapy (metoprolol, 40 to 60 mg/day) coupled with an ACE inhibitor on global and regional left ventricular (LV) function in patients with dilated cardiomyopathy. In 12 patients with dilated cardiomyopathy, the global LV ejection fraction (EF), regional EF (rEF), and regional ejection time (rET) were determined by sector analysis of the radionuclide ventriculogram before and after therapy (duration 14±9 months). The coefficients of variation of rEF and rET were calculated as indexes of the heterogeneity of regional LV systolic wall motion. EF increased significantly from 20%±8% to 30%±8% (p<0.05) in patients who received β-blockade and an ACE inhibitor (n=5). Furthermore, the coefficients of variation of rET decreased from 27%±13% to 16%±7% (p<0.05). In contrast, patients treated with an ACE inhibitor only (n=7) showed no significant improvements in any of these parameters. These results suggest that, compared with an ACE inhibitor alone, β-blockade improves global and regional LV function in dilated cardiomyopathy by synchronizing myocardial contraction.