Coronary hemodynamic effects of angiotensin inhibition by captopril and teprotide in patients with congestive heart failure.

The coronary hemodynamic effects of vasodilator therapy with angiotensin-converting enzyme inhibitors (captopril and teprotide) were studied in 11 patients with ischemic heart disease and severe congestive heart failure (CHF). Over 2 hours, systemic vascular resistance was reduced from 2,408 +/- 240 to 1,715 +/- 170 dynes . s . cm-5 (p less than 0.001), and cardiac output improved 18%, resulting in lower arterial pressure (101 +/- 8 to 86 +/- 5 mm Hg, p less than 0.001) and left ventricular filling pressure (30 +/- 2 to 21 +/- 2 mm Hg, p less than 0.001). Coronary sinus thermodilution blood flow paralleled perfusion pressure but did not significantly vary overall (160 +/- 20 to 133 +/- 12 ml/min, difference not significant [NS]). Coronary vascular resistance was unchanged. Although the left ventricular stroke work index rose slightly (37.7 +/- 8.8 to 41.3 +/- 7.9 g l m/m2, p less than 0.05), there was no change in the coronary arteriovenous oxygen content difference (10.8 +/- 1.0 to 10.4 +/- 1.0 ml/10 ml, NS) or calculated myocardial oxygen consumption (16.4 +/- 1.9 to 13.9 /- 1.6 ml/min, NS). The heart rate-systolic blood pressure product declined significantly during this period (8,824 +/- 703 to 7,087 +/- 514 beats . mm Hg, p less than 0.02); this relief of cardiac effort was a function of the pretreatment plasma renin activity. A derived index of external myocardial efficiency improved 37% (19 +/- 3 to 26 +/- 6, p less than 0.05), reflecting greater left ventricular work without increased oxygen demand. Enhancement of myocardial performance after converting enzyme inhibition appears dependent on reduction of angiotensin-mediated ventricular afterload and preload. The lack of coronary vasomotor effects in patients with advanced ischemic cardiomyopathy may reflect limited coronary vascular reserve. Improvement of heart failure in these patients developed without evidence of myocardial ischemia, since balance was maintained between oxygen supply and demand.