Of 518 consecutive patients undergoing percutaneous transluminal coronary angioplasty for 571 coronary lesions, 184 eventually underwent coronary artery bypass because of angioplasty failure. Delayed coronary bypass (1 week to 19 months) was done in 27 patients with no deaths. Immediate bypass was done in 87 patients with two deaths, both of which were caused by further dissection of the artery after angioplasty. Urgent bypass was required in 63 patients who were in unstable condition because of ischemia on the electrocardiogram (52 patients), unrelieved angina (57 patients), or hypotension (13 patients). There was one death in this group. In the remaining seven patients, urgent coronary bypass was done because of cardiac arrest (three deaths). Myocardial complications occurred in 23 of the 70 unstable patients, including the seven patients with cardiac arrest. There were only eight completed myocardial infarctions in the 70 unstable patients and a completed myocardial infarction rate of 11 of 184 (6.0%) overall. In the 10 patients in whom extracorporeal circulation was established within 25 minutes of myocardial insult, mortality and myocardial complications were completely avoided. The remaining patients in the urgent group were placed on cardiopulmonary bypass within 26 to 300 minutes (mean 82 minutes). Operative mortality (3.3%), completed myocardial infarction (6.0%), myocardial infarction in unstable patients (32.9%), postoperative hemorrhage (5.0%), and sternal problems (2.8%) were all significantly different from those in 3,500 consecutive coronary bypasses not following angioplasty, that were done in 1982.