Mechanism of relief of angina after coronary bypass surgery: an angiographic study.

Coronary angiography was performed before and after coronary revascularization in 67 patients. The interval between studies ranged from 1 to 38 months (average 9.9). The patients were separated into four clinical groups on the basis of their symptoms at the time of restudy; Group I, 13 asymptomatic patients; Group II, 19 patients with nonanginal chest pain (18 cases) or dyspnea (1 case); Group III, 12 patients whose angina was relieved but not eliminated; and Group IV, 23 patients whose angina was not alleviated. The graft patency rate was 72 percent in Group I, 78 percent in Group II, 61 percent in Group IIII and 34 percent in Group IV. The sum of diseased, but not bypassed and unsuccessfully bypassed arteries per patient was 1.6 in Groups I and II. 2.9 in Group III and 4.0 in Group IV. The incidence of perioperative myocardial infarction, defined using enzymatic and electrocardiographic criteria, was 8 percent for Group I, 26 percent for Group II, 25 percent for Group III and 52 percent for Group IV. Anginal relief after coronary bypass surgery is achieved by successful and complete revascularization rather than by perioperative myocardial infarction.