Differentiation of myocardial ischemia and left ventricular aneurysm in the genesis of exercise-induced ST-T changes in previous anterior myocardial infarction.
We attempted to differentiate between myocardial ischemia and left ventricular asynergy as the underlying mechanisms of exercise-induced ST-segment elevation in patients with previous myocardial infarction (MI). Sixty patients with previous anterior MI, who underwent stress myocardial scintigraphy (SMS) and coronary angiography (CAG), which revealed a single vessel disease of the left anterior descending artery, were entered in this study. SMS and CAG were performed within 3 months of MI onset, and SMS and ECG were quantitatively analyzed. T wave changes to a complete upright position with concomitant ST-segment elevation (T-dominant ST-elevation) was seen in 56% of the patients with post-MI angina pectoris (N = 16) and in 50% of those with significant redistribution in SMS (n = 20). On the other hand, ST-segment elevation without T wave reversion (ST-dominant ST-elevation) was seen in 43% of patients with severe LV asynergy (akinesis and dyskinesis, n = 39) and in 50% of those with severe scintigraphic defect in delayed images (relative thallium uptake less than or equal to 40%, n = 10). When these findings were combined, T-dominant ST-elevation had sensitivity and specificity of 54% and 78%, respectively, for the diagnosis of myocardial ischemia, while the corresponding values for ST-dominant ST-elevation were 44% and 100%, for the diagnosis of severe ventricular asynergy. We conclude that the two underlying mechanisms, ischemia and asynergy, may produce different changes in ST-T shape in patients with previous myocardial infarction.
D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000209:etiology; D000792:Angiography; D003327:Coronary Disease / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006322:Heart Aneurysm / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D005082:Physical Exertion; D011877:Radionuclide Imaging