Intracoronary enalaprilat improves metabolic coronary vasodilation in patients with idiopathic dilated cardiomyopathy

Coronary flow reserve is reduced in patients with idiopathic dilated cardio myopathy (DCM). We examined acute effects of intracoronary enalaprilat on m etabolic coronary vasodilation during pacing tachycardia in patients. Coron ary blood flow (Doppler guidewire) and diameter (quantitative angiography) were measured in seven patients with DCM and seven control subjects. In the DCM group, tachypacing increased coronary blood flow by 37 +/- 22% from th e baseline before enalaprilat and by 65 +/- 22% (p < 0.01 vs. before treat ment) after enalaprilat (0.5 mu g/kg/min for 5 min, i.c.) at comparable dou ble product. Pacing-induced dilation of the epicardial coronary artery also was greater after enalaprilat (p < 0.05). Effects of enalaprilat on corona ry blood flow and diameter during pacing tachycardia were abolished by pret reatment with intracoronary administration of the nitric oxide (NO) synthes is inhibitor, N-G-monomethyl-L-arginine. These beneficial effects of enalap rilat on large and small coronary vasodilation were not observed in control patients. Thus, intracoronary enalaprilat acutely augmented dilator respon ses of the large and small Coronary arteries to pacing tachycardia in patie nts with DCM, and NO appeared to play an important role in mediating the ef fects of enalaprilat. These favorable effects of enalaprilat on the coronar y circulation may be of clinical significance in patients with heart failur e due to nonischemic DCM. Further long-term studies of the effects of angio tensin-converting enzyme inhibition on coronary vasodilation will be needed in this population.