Unstable angina is an inhomogenous syndrome. A substantial percentage of patients, ranging from 12 to 30% in most series, develops acute myocardial infarction or dies suddenly soon after their hospitalization, while the remainder have a benign prognosis without adverse coronary events. Unstable angina is a complex condition such as angina at rest, crescendo angina, new onset angina and postinfarction angina. These variable clinical presentations suggest that unstable angina have a heterogenous pathogenesis and prognosis. We divided unstable angina into 5 groups and studied the relationship between clinical presentations and coronary angiographic morphology.

One hundred sixty six patients were selected from the patients who were diagnosed as an unstable angina between January 1989 and March 1991, at Hallym University Hospital. Angiography was performed in patient with typical angina symptoms and transient ECG changes of myocardial ischemia. Coronary angiogram was done as usual method. Calcification of coronary artery as well as the presence of collateral circulation were recorded. Ergonovine test was performed in patients with near normal or normal angiogram. Coronary lesions were morphologically classified as follows; type A is simple lesion such as symmetric, concentric narrowing and smooth border. and type B is complex lesion such as asymmetric, eccentric, ulcerated narrowing and irregular border.

These groups were classified as follows; Group I(represented the patients with angina at rest but typical Prinzmetal angina was excluded) 30 patients, Group II(represented the patients with crescendo angina) 24 patients, Group III(represented the patients with new onset angina) 62 patients, Group IVA(represented the patients with early postinfarction angina within 2 weeks after AMI) 34 patients, Group IVB(represented the patients with delayed postinfarction angina) 16 patients, There were no significant differences in age and sex among the 5 groups. Locations of involved vessel were similar among the five groups, and left anterior descending artery was most frequently(mean 60%) involved. Single vessel disease was frequently observed in new onset angina and early postinfarction angina(Group III^*, IVa^** 48%, 65% VS Group II, IVB 25%, 19% respectively, ^*p<0.05, ^**p<0.005) whereas multivessel disease was frequent in crescendo angina and delayed postinfarction angina(Group II, IVB 51%, 76% VS Group II, IVA 16%, 27% respectively, p<0.005). More than two third of patients with unstable angina had complex B lesion of coronary artery (77%), but in new onset angina simple A lesion was frequently observed (Group III 45% VS Group I, IVA, IVB 16%, 10%, 13% respectively, p<0.05). The frequency of calcification increased in early postinfarction angina(Group IVA 18% VS Group III 3%, p<0.05). The frequency of coronary collateral circulation increased in cresendo angina, early postinfarction and delayed postinfarcion angina(Group II^*, IVA^*, IVB^** 38%, 35%, 50% VS Group III 10% respectively, ^*p<0.005.^**p<0.0001). Incidence of coronary vasospasm was higher in resting angina than the others(Group I^*, III 30%, 19% VS Group II, IVA 4%, 6% respectively, ^*p<0.02). The coronary vasospasm was frequently observed in an insignificant lesion(insignificant lesion/total vasopasm: 12/24(50%)). Early postinfarction angina had frequent intracoronary thrombus in infact-related artery(incidence of thrombus : Group IVA^*, IVB 21%, 13% VS Group I, II, III 3%, 4%, 5% respectively, ^*p<0.05).

This study suggests that patients with unstable angina pectoris may be heterogeneous groups. Coronary angiography must be performed in patients with unstable angina, in order to classify the clinical correlates with each possible angiogrphic finding that could affect treatment modality and outcome of cardiac events.