Relationship between electrocardiographic patterns and angiographic features in isolated left circumflex coronary artery disease

The relation of electrocardiographic (ECG) patterns to clinical and angiographic features was assessed in 89 patients with isolated left circumflex coronary artery (LCx) disease (46 with and 43 without myocardial infarction). ECG abnormalities were present in 75 patients; there were isolated Q waves in 20, an abnormal R wave in lead V1 with or without inferior and/or lateral Q waves in 21, and isolated ST-T wave changes in 34 cases. Inferior abnormalities on the electrocardiogram were similar in patients with proximal or distal stenoses of the LCx, but an abnormal R wave in lead V1 correlated with proximal LCx stenosis (p less than 0.01). Lateral abnormalities were more common in stenoses of the obtuse marginal branch and proximal LCx than in distal stenosis (all p less than 0.01). Compared with patients without myocardial infarction with or without ST-T-wave changes and those with infarction without an abnormal R wave in lead V1, patients with LCx-related infarction and an abnormal R wave in lead V1 associated with inferior and/or lateral Q waves had larger left ventricular end-diastolic and end-systolic volumes, lower ejection fraction, higher incidence of total occlusion of proximal LCx without collateral vessels, and more cardiac events during follow-up. This study suggests that an abnormal R wave in lead V1 associated with lateral abnormalities on the standard electrocardiogram may be clinically useful in predicting proximal LCx stenosis and identifying a subset of postinfarction patients with left ventricular dysfunction due to a large infarct size.