24 patients with coronary artery disease underwent intravenous digital subtraction angiocardiography at rest and during exercise before and after percutaneous transluminal coronary angioplasty (PTCA). Before PTCA mean pulmonary artery pressure increased pathologically in 20 patients (on average from 22 +/- 4 to 40 +/- 9 mm Hg, p less than 0.001). The increase in cardiac index from 4.2 +/- 1.3 to 6.2 +/- 2.01 I X min-1 X m-2 (p less than 0.01) was achieved by an increase in heart rate from 77 +/- 13 to 119 +/- 16 min-1 (p less than 0.001) as stroke volume remained unchanged during exercise (52 +/- 14 ml X m-2, resting value: 53 +/- 13 ml X m-2). Though end-systolic volume increased from 32 +/- 11 to 41 +/- 13 ml X m-2 (p less than 0.001) and ejection fraction fell from 63 +/- 8% to 56 +/- 10% (p less than 0.005), stroke volume remained unchanged due to an enhanced diastolic filling (EDVI: 86 +/- 19 ml X m-2 at rest, 92 +/- 18 ml X m-2 during exercise, p less than 0.001). After angiographically successful PTCA in 21 of 24 patients average mean pulmonary artery pressure during exercise remained pathologically elevated (36 +/- 9 mm Hg, no significant difference from value before PTCA). It normalized in only 6 of 17 patients. On the other hand there was a marked improvement of left ventricular systolic performance. Ejection fraction during exercise (65 +/- 11%) was higher than before PTCA (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)