The patient was a 67-year-old man who complained of shortness of breath. Coronary angiography showed 90% stenosis in proximal left anterior descending (LAD). He therefore underwent a directional coronary atherectomy (DCA). During the procedure, coronary artery perforation occurred at the origin of the LAD, which caused cardiac tamponade. Surgical pericardial drainage was done. Though bleeding was successfully controlled and his general condition improved, coronary angiography showed a coronary aneurysm at the site of the perforation 2 weeks later. Patch closure of the coronary aneurysm and patch angioplasty of the left main coronary artery were performed. Distal LAD was bypassed with the left internal thoracic artery in case of acute thrombosis. He recovered uneventfully and was discharged 14 days after operation.