The safety and therapeutic benefits of percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery, the left circumflex coronary artery or both were assessed in 61 patients with chronic (greater than 3 months) occlusion of the right coronary artery. Recanalization of the right coronary artery was not performed before dilatation of left coronary artery lesions. All lesions could be dilated without an acute ischemic event in the catheterization laboratory. However, three patients underwent coronary artery bypass surgery within the first 8 days after coronary angioplasty. There were no in-hospital deaths. Of the remaining 58 patients, 51 (88%) had repeat angiography at a mean of 5.2 +/- 2.5 months. Patients were divided into two groups according to the presence (n = 17) or absence (n = 34) of restenosis defined as greater than or equal to 50% diameter stenosis at the dilated site. Baseline characteristics were comparable. The mean value for angina functional class at follow-up was significantly better in the group without than in the group with restenosis (0.4 +/- 0.6 vs 2.1 +/- 1.1, respectively; p less than 0.001). Sixty-five percent of the patients without restenosis were asymptomatic at follow-up. Seventy-five percent of the predicted maximal physical capacity was reached by 76% of the patients without restenosis compared with 33% in the group with restenosis (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)