Transient ST-segment in unstable angina. Clinical and hemodynamic significance.

The significance of the direction of the ST-segment shifts on the 12-lead electrocardiogram was evaluated in 82 consecutive patients with unstable angina. Eighteen patients with ST-segment elevation (group I) were compared with 64 patients with ST-segment depression (group II). There was no difference between group I and group II with regard to age, sex, or history of previous myocardial infarction. There also was no difference in the angiographic extent, location or severity of the coronary artery disease, collaterals, or resting hemodynamics. A larger proportion of patients in group I presented with recent onset angina. Life-threatening arrhythmias were more frequent in group I but were uncommon in both groups. A normal resting electrocardiogram was associated with normal ventricular function in both group I and group II but was associated with single vessel disease only in group I. An abnormal resting electrocardiogram was associated with multiple coronary vessel disease and abnormal ventricular function in both groups. Single vessel disease was encountered twice as frequently in group I but this difference was not statistically significant. Left main coronary artery disease was found only in group II.