In 32 patients with successful percutaneous transluminal coronary angioplasty (PTCA), we performed treadmill exercise tests (TMET) before and about one month after PTCA to assess the correlation between the improvement in coronary artery lesions and exercise tolerance. Either the Bruce protocol (B: n = 12) or the modified Bruce protocol (MB: n = 20) was used; with the latter being applied to patients whose cardiac function seemed depressed. In 15 patients, oxygen consumption (VO2) was measured by analyzing the expired gases, 13 patients underwent exercise thallium-201 myocardial perfusion scintigraphy before and after PTCA, whose results were compared with those of TMET. In both B and MB protocols, the treadmill walking time was significantly prolonged after PTCA, compared to that before PTCA (B: 7.4 +/- 1.3 vs 9.5 +/- 1.9, MB: 11.4 +/- 3.5 vs 12.7 +/- 3.5 min). Heart rates (HR) and rate pressure products (RPP) were significantly increased after PTCA in both protocols (HR B: 139 +/- 18 vs 154 +/- 17, MB: 121 +/- 20 vs 137 +/- 19 bpm, RPP B: 26,500 +/- 5,600 vs 30,300 +/- 6,700, MB: 19,400 +/- 6,200 vs 22,700 +/- 6,600 mmHg.bpm), however, systolic blood pressure did not change significantly after PTCA in either protocol. While there was a significant improvement in VO2 after PTCA (21.6 +/- 6.3 vs 25.7 +/- 4.2 ml/kg/min), the O2-pulse remained unchanged. Thallium-201 myocardial scintigraphy revealed improvement of myocardial perfusion in 8 of the 13 cases examined.(ABSTRACT TRUNCATED AT 250 WORDS)