Electrocardiographic prediction of ejection fraction and site of LAD occlusion in anterior myocardial infarction

Q-wave anterior myocardial infarctions due to occlusion of the left anterior descending artery (LAD) are generally associated with the most extensive left ventricular damage. The presence of abnormal Q waves on the electrocardiogram (ECG) provides important information to localize the site of left ventricular infarction. However, the relationship between abnormalities of the QRS morphology in the precordial leads and angiographic information such as ejection fraction and the site of LAD occlusion (before or after the first septal perforator) has not been studied extensively. Seventy-three patients with single-vessel disease with complete LAD occlusion, abnormal QRS morphology in leads V₁-V₄ on ECG, and abnormal wall motion with contrast ventriculography were studied retrospectively. LAD occlusions were proximal to the first septal perforator in 33 patients and distal in 40 patients. Q waves were present in 59 patients, and the other 14 patients had either minimal R waves (<0.25 mm), poor R-wave progression, or R-wave regression. A significantly higher ejection fraction was associated with the presence of R wave in V₂ (0.52 ± 0.18 vs. 0.39 ± 0.15 in the absence of R wave, p<0.003). LAD occlusion after and before the first septal perforator was associated with R wave in V₂ in 67 and 36% of patients, respectively. Sensitivity and specificity of predicting occlusion after the first septal perforator based on R wave in V₂ was 0.68 and 0.64, respectively. In patients with anterior myocardial infarctions, occluded LAD artery, and abnormal QRS morphology in the precordial leads, the presence of R wave in V₂ is a useful predictor of higher ejection fraction. The prediction of site of LAD occlusion in relation to the first septal perforator based on ECG findings is limited and probably not sufficiently specific or sensitive to be of clinical use.