Effects of Long-term Monotherapy With Enalapril, Metoprolol, and Digoxin on the Progression of Left Ventricular Dysfunction and Dilation in Dogs With Reduced Ejection Fraction

Background Recent clinical trials have suggested that ther-apy with angiotensin-converting enzyme inhibitors in asymp-tomatic patients with reduced left ventricular (LV) function can significantly reduce the incidence of congestive heart failure compared with patients receiving placebo. In the present study, we examined the effects of long-term monother-apy with enalapril, metoprolol, and digoxin on the progression of LV systolic dysfunction and LV chamber enlargement in dogs with reduced LV ejection fraction (EF). Methods and Results LV dysfunction was produced in 28 dogs by multiple sequential intracoronary microembolizations. Embolizations were discontinued when LVEF was 30 % to 40%. Three weeks after the last embolization, dogs were randomized to 3 months of oral therapy with enalapril (10 mg twice daily, n=7), metoprolol (25 mg twice daily, n=7), digoxi