The immediate effects of successful percutaneous transluminal coronary angioplasty on global and regional left ventricular function were assessed by comparing 30 degrees right anterior oblique left ventricular angiograms performed immediately before and after angioplasty on 39 patients undergoing 42 successful procedures. Mean (+/- SD) lesion stenosis decreased from 88 +/- 10% to 35 +/- 11% (p less than or equal to 0.001), whereas left ventricular ejection fraction increased from 57 +/- 11% to 64 +/- 10% (p less than or equal to 0.001) for the entire group. Left ventricular functional changes were further subgrouped according to stability of angina. Eighteen procedures were performed on 17 patients with stable angina: 24 procedures were performed on 22 patients with unstable angina defined as angina at rest or on minimal activity or recently accelerated angina. There were no significant subgroup differences in mean age, gender ratio, vessel anatomy, drug therapy or extent of coronary stenosis before or after angioplasty. Global ejection fraction increased significantly for the unstable group (from 54 +/- 11% to 66 +/- 9%, p less than or equal to 0.001) but was unchanged for the stable group (from 61 +/- 9% to 61 +/- 11%, p = NS). In unstable angina, regional ejection fraction (segmental area method) increased for both jeopardized (from 37 +/- 11% to 52 +/- 9%, p less than or equal to 0.001) and nonjeopardized myocardial segments (from 43 +/- 13% to 51 +/- 13%, p less than or equal to 0.001), but improvement was significantly (p less than or equal to 0.02) greater in jeopardized segments.(ABSTRACT TRUNCATED AT 250 WORDS)