Clinical significance of the disappearance of septal Q waves after the onset of myocardial infarction: correlation with location of responsible coronary lesions.

We investigated the relationship between the disappearance of septal Q waves after myocardial infarction (MI) and the location of the culprit lesion. We studied 82 patients following their first anteroseptal MI who had an electrocardiogram performed before the MI. Septal Q waves were detectable before MI in 56 patients and disappeared after MI in 17 of those patients. The culprit lesion was located proximal to the origin of the first septal branch (S1) in 13 patients (76%). Disappearance of septal Q waves following MI predicted that the culprit lesion was proximal to the origin of S1 (sensitivity, 42%; specificity, 84%; predictive value, 76%; and accuracy, 61%). If septal Q waves that were detected before MI disappeared after MI, the culprit lesion was located proximal to the origin of S1 in 76% of the patients. This finding may be clinically useful in caring for patients following MI.