Electrocardiographic localization of coronary artery narrowings: studies during myocardial ischemia and infarction in patients with one-vessel disease.

To investigate the accuracy of the 12-lead ECG in localizing the site of coronary artery narrowings, we reviewed abnormal ECGs obtained during myocardial infarction, spontaneous angina or exercise stress testing in 134 patients with angiographically documented one-vessel disease. The presence of Q waves, ST-segment elevation and T-wave inversion in leads I, aVL and V1--V4 were all highly correlated with the presence of left anterior descending coronary artery disease (p less than 0.001), and the same ECG findings in leads II, III and aVF were associated with right (RCA) or circumflex coronary artery (LCx) narrowings (p less than 0.001). In contrast, ST depression alone was not useful in predicting the site of coronary artery narrowing. Q waves correctly identified the location of the coronary disease in 98% of cases, ST elevation in 91%, T-wave inversion in 84%, and ST depression in 60%. No electrocardiographic criteria distinguished RCA from LCx disease, even in patients with a right-dominant circulation. These findings should lead to a better understanding of the value and limitations of the 12-lead ECG in localizing coronary artery disease.