OBJECTIVE To evaluate the outcome in patients who underwent directional coronary atherectomy after unsuccessful balloon angioplasty. METHODS We conducted a retrospective computerized data bank search of patients in whom unsuccessful balloon angioplasty and subsequent "rescue" coronary atherectomy had been performed at the Mayo Clinic between Nov. 1, 1988, and May 1, 1993. METHODS Among the 336 patients who underwent directional coronary atherectomy during the study period, in 16 the procedure was a rescue attempt. The mean age of these 16 study patients was 67 years. The following vessels were treated: left anterior descending coronary artery, six patients; right coronary artery, six; circumflex artery, two; and saphenous vein graft, two. Coronary angioplasty had failed because of dissection in eight patients, elastic recoil without evident dissection in seven, and recurrent thrombus without evident dissection in one. RESULTS After coronary atherectomy, the mean stenosis was 41% (in comparison with 90% before coronary angioplasty and 71% after coronary angioplasty). Both angiographic success (20% or more decrease in stenosis after tissue removal and a final stenosis of less than 50%) and clinical success (angiographic success without in-hospital Q-wave myocardial infarction, bypass operation, or death) were achieved in 10 patients. Adventitia was obtained in two patients, both of whom underwent atherectomy for elastic recoil. In six patients, a stenosis of more than 50% remained after atherectomy; one patient suffered a Q-wave myocardial infarction, and one underwent emergent coronary artery bypass grafting. No deaths occurred in the study group. During follow-up (mean, 22 +/- 19 months), one patient suffered a non-Q-wave myocardial infarction, and two others underwent elective coronary artery bypass grafting. Eleven patients were asymptomatic at last contact. Repeated angiography, done in five patients a mean of 3.4 +/- 3.1 months after the procedure, showed restenosis in three. CONCLUSIONS Rescue directional coronary atherectomy seems to be safe and effective in achieving angiographic and clinical successes in carefully selected patients after unsuccessful coronary angioplasty.