BACKGROUND: Exercise induced ST-segment depression in patients after coronary angioplasty is frequently observed but the mechanism responsible for exercise induced myocardial ischemia early after successful coronary angioplasty is poorly understoodd. The object of this study is to investigate potential determinants of this phenomenon by analizing the clinical, exercise testing, and angiographic characteristics in patients with exercise induced ST-segment depression. METHODS: The study group comprised 13 patients with exercise induced ST-segment depression(Positive group,M:12, mean age:59+/-9year) and 26 patients without exercise induced ST-segment depression(Negative group, M; 22, mean age; 55+/-13 year) after succeessful coronary angioplasty in single vessel disease. We compared preangioplasty clinical, angiographic, and hemodynamic variables in group with positive and negative results on exercise testing after successful PTCA. RESULTS: 1) Clinical characteristics: The initial diagnosis were acute myocardial infarction in 5, unstable angina in 8 patients at positive group, and 16 and 10 patients at negative group, respectively. There were no significant different in initial diagnosis, risk factor for coronary artery disease, and medication used before exercise test at between two groups. 2) Cornary angiography and PTCA: The maximal ballooning size were significantly smaller in positive group than negative group(2.7+/-0.5 vs 3.1+/-0.4mm, 2.9+/-0.4mm, vs 3.2+/-0.4mm, respectively(p<0.05) but there were no significantly different in ejection fraction, end-diastolic volume, end-systolic volume before PTCA. degree of stenosis of lesion before and after PTCA, total ballooning time, balloon pressure, lesion site and infarction relation of lesion at between two groups. 3) Exercise test: The mean time from angioplasty to the performance of exercise testing were 9.5+/-4.0 days in positive group and 6.1+/-4.5 days in negative group. The mean depression of ST-segment was 1.5+/-0.5mm and was predominantly noted in lateral leads(V4-6)(9/13:69%). There were no significantly different in total exercise time, rate-pressure product, and metabolic equivalents-exercise time at positive and negative group. But positive results at follow up exercise test were significantly higher in positive group(p<0.05). CONCLUSION: There were no definite determinating factors for exercise induced ST-segment depression early after successful coronary angioplasty by analizing the clinical, angiographic, and exercise testing variables. The pathophysiologic mechanism of this findding remain to be elucidated, especially for association of microvascular functional alternation.