We investigated the acute effect of the new long-acting ACE-inhibitor ramipril on angina-limited exercise tolerance and exercise-induced ST-depression in 18 normotensive patients with angiographically confirmed coronary artery disease in a double-blind, placebo-controlled study. Patients underwent a repeat exercise ECG 24 hours following either 5 mg ramipril p.o. or placebo. Plasma-ACE activity (nmol/min x ml) in the ramipril-group (n = 8) was significantly reduced 24 hours after 5 mg ramipril compared to placebo (n = 10): 14.0 +/- 2.0 vs 87.2 +/- 13.5, p less than 0.001. Exercise-induced ST-segment depression was not different before and after ramipril or placebo. Heart rate at rest and during angina-limited exercise was not different between the first exercise-ECG and that after ramipril or placebo, nor between the groups. Systolic arterial pressure (mmHg) was slightly, but insignificantly, lower after than before ramipril at rest (113.8 +/- 5 vs 125 +/- 6.8) and at maximal exercise, 1.5 watt/kg (150 +/- 9.4 vs 158.3 +/- 13.3). In the placebo group, blood pressure at rest and during exercise was not different before and after placebo: 126 +/- 4.7 vs 125.5 +/- 7.5 and 157.5 +/- 3.8 vs 158 +/- 3.6. Rate-pressure-product (mmHg/min x 1000) at rest prior to (8.42 +/- 0.83 and 8.95 +/- 0.51) and after ramipril or placebo (8.00 +/- 0.94 and 8.93 +/- 0.71) showed no significant difference. Similarly, rate-pressure-product at maximal exercise was equal among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)