PURPOSE--Assess the efficacy of the different strategies employed in the management of acute closure and verify the late prognosis of patients who develop this complication. METHODS--From january 1987, through December 1990, 2315 consecutive patients underwent percutaneous transluminal coronary angioplasty (PTCA) in our Institution. We analyzed 100 patients who had had acute closure of the dilated vessel determining the total incidence of myocardial infarction and death, the effectiveness of the different treatment strategies and clinical and angiographic predictors of poor in-hospital outcome. Late follow-up was obtained in the hospital survivors. RESULTS--The incidence of acute myocardial infarction in the group of 100 patients was 57; death occurred in 12of the patients. Forty-one individuals were referred to emergency bypass surgery, 35 received clinical treatment and 24 underwent redilatation of the vessel. Those managed clinically had a higher incidence of myocardial infarction compared to the ones who underwent either redilatation or surgery (74.3versus 50and 48.8). The in-hospital mortality rate was significantly higher in patients with left ventricular ejection fraction < 45(44.4, p < 0.001) and in procedures involving the left anterior descending artery (20, p < 0.05); patients undergoing repeat dilatation had the lower death rate (4.2versus 8.6in the clinical group and 17.1in the surgical group). Late follow-up was obtained in 65 of 88 hospital survivors (mean follow-up = 17 months). Patients who underwent repeat dilatation were significantly less symptomatic in the follow-up than those who received medical therapy during the acute phase (89versus 60.9of patients without symptoms respectively, p < 0.05). Patients who were referred to surgery had also a tendency towards having less symptoms (87.5of asymptomatic patients in the late follow-up) although the difference was not statistically significant (0.01 > p > 0.05). CONCLUSION--Acute coronary occlusion is a serious complication of angioplasty and is associated with high rates of major complications (myocardial infarction, death). Low left ventricular ejection fraction and PTCA involving the left anterior descending are predictors of higher in-hospital mortality in patients with acute closure. Late outcome is less favourable in patients submitted to clinical treatment in the acute phase.