Coronary perforation is a rare but serious complication that occurs during percutaneous coronary intervention (PCI). This study examines the frequency of coronary perforation during PCI, evaluates the management strategies used to treat perforations, and describes the long-term prognosis of patients who have developed coronary perforation during PCI. Coronary perforations were found in 69 (0.93%) of 7,443 consecutive PCI procedures, occurring more often after use of a new device (0.86%) than after use of balloon angioplasty (0.41%) (p<0.05). Coronary perforation was attributable solely to the coronary guidewire in 27 (0.36%) cases. Coronary perforations were divided into 2 types: (1) Those with epicardial staining without ajet of contrast extravasation (type I, n=51), and (2) those with a jet of contrast extravasation (type II, n= 18). Patients with type I and type II perforations were managed by observation only (35% and 0%, respectively), reversal of anticoagulation (57% and 94%), pericardiocentesis and drainage (27% and 61%), and prolonged perfusion balloon angioplasty (16% and 100%). Two patients with type II perforations required emergency coronary artery bypass surgery. There were no in-hospital deaths. Late pseudoaneurysms developed in 18 (28.6%) patients during the 13.4 +/- 11.3 months' follow-up period, and were more common in patients with type II perforations (72.2% vs 11.1% with type I perforations; p<0.001). During the follow-up period, no patient had evidence of coronary rupture. The results suggest that coronary perforation is uncommon after PCI, and can be managed without cardiac surgery in the majority of cases. Late pseudoaneurysms developed in some patients, particularly in patients with type II perforations, but there were no late consequences of coronary perforation after PCI.