The role of systematic emergency percutaneous transluminal coronary angioplasty (PTCA) in patients with spontaneous reperfusion during myocardial infarction is debated. We retrospectively examined the inhospital outcome of 47 consecutive patients with myocardial infarction < 6 hours and angiographically proven spontaneous patency of the infarct artery managed without initial PTCA. There was one death (2.1%) and no incidence of reinfarction. Predischarge angiography showed regression of the culprit coronary lesion to < 50% stenosis in 23% of the patients, therefore obviating the need for PTCA. However, 17% of the patients had acute recurrent ischemia, requiring emergency intervention in 10.6%. Comparison with matched patients in whom Thrombolysis in Myocardial infarction grade 3 patency was achieved by thrombolysis or by primary PTCA showed that patients with spontaneous patency tended to have smaller infarctions, as judged from a lower peak creatine kinase level (1132 +/- 1002, 2051 +/- 1536, and 2715 +/- 2146 i.u., respectively; p = 0.001) and a higher left ventricular ejection fraction (56.4%, 47.9%, and 48.7% respectively; p = 0.02). In conclusion, these patients have an excellent inhospital outcome, with evidence of less myocardial damage than in patients in whom reperfusion therapy was required to achieve TIMI 3 patency. Initial conservative treatment appears safe.