Coronary vasodilatation and improved myocardial lactate metabolism after angiotensin converting enzyme inhibition with cilazapril in patients with congestive heart failure

Abstract

The effects of angiotensin converting enzyme inhibition on systemic and coronary hemodynamics and on myocardial lactate metabolism were investigated before and 2 and 6 hours after cilazapril at rest and during supine submaximal exercise in 10 patients with New York Heart Association class II or III chronic congestive heart failure. Angiotensin converting enzyme inhibition, indicated by a significant increase in plasma renin activity, resulted in significant reductions in blood pressure and systemic vascular resistance. Myocardial oxygen demand decreased (resting double product 10.9 ± 3.7 vs 12.2 ± 3.8 mm Hg beats/min 10 −3; p < 0.05), but coronary sinus blood flow remained unchanged and calculated coronary resistance decreased (0.45 vs 0.5 units, rest 6 hours; p < 0.05) suggesting coronary vasodilatation. Changes in coronary vascular resistance were directly related to changes in systemic vascular resistance ( r = 0.75, p < 0.5). Myocardial lactate extraction increased at rest (47 ± 60 vs 134 ± 132 μmol/min; p < 0.5) and during exercise (27 ± 54 vs 491 ± 317 μmol/min; p < 0.05) both in patients with coronary artery disease (n = 5) and idiopathic dilated cardiomyopathy (n = 5). Resting lactate production was converted to lactate extraction in two patients with coronary artery disease. Neither plasma catecholamine nor atrial natriuretic peptide concentrations changed significantly. The results suggest coronary vasodilatation and improved aerobic myocardial metabolism by angiotensin converting enzyme inhibition in patients with congestive heart failure.