Previous coronary artery bypass grafting as an adverse prognostic factor in unstable angina pectoris.

Among 252 patients hospitalized for unstable angina in 1982 and 1983, 54 (21%) had undergone coronary artery bypass grafting (CABG) a mean of 55 months earlier (range 1 to 168) (CABG patients). This group was compared with a group of 54 randomly selected patients with unstable angina without previous CABG (control patients). The 2 groups did not differ with respect to clinical characteristics at admission or hospital course. Coronary arteriograms, recorded in all but 4 CABG patients, revealed multivessel stenoses of at least 70% luminal diameter in 40 CABG and 32 control patients (p less than 0.05), but when patent grafts were considered, the groups were comparable. Overall, 48 of 112 grafts were totally occluded and 14 had stenoses at least 70% in diameter. Complete or almost complete revascularization was feasible in 39 of 52 control and only 9 of 42 CABG patients (p less than 0.001). By 1 year, 46 control patients and 20 CABG patients had undergone CABG or coronary angioplasty (p less than 0.001); 42 of 53 control patients and only 22 of 50 CABG patients were in functional class 0 or I (p less than 0.001). Cumulative adverse events (5 deaths, 10 myocardial infarctions and 15 cases of recurrent unstable angina) were more frequent in the CABG group, 20 vs 10 (p less than 0.05). Thus, although their clinical features and hospital course are similar, patients with unstable angina who have undergone previous CABG do not do as well as other patients with unstable angina because they are less amenable to revascularization.