Relation of Exercise-induced ST-Segment Elevation to Myocardial Viability in Recent Q-Wave Myocardial Infarction

Detection of viable myocardium in the infarct zone is clinically important for identifying patients who will benefit from revascularization. To determine whether exercise-induced ST segment elevation in Q-wave myocardial infarction (MI) can be used as a simple method for viability assessment, we studied 30 patients with a first recent Q wave MI and with almost isoelectric (<1.0 mm elevated) STsegment on the resting electrocardiogram. Viability was determined by exercise T1-201 Single Photon Emission Computerized Tomography (SPECT) 9±2 weeks after MI.T1-201 reinjection protocol was used in patients who showed no redistribution on standard 3-hour images (persistent defect). Regional wall motion on ventriculography was graded semiquantitatively on a 7-segment model (normal=O; dyskinetic=3). Patients were divided into two groups according to the presence (group 1, n= 16) or absence (group 2, n=14) of exercise-induced ST elevation. Viability was detected in all 16 patients in group 1 and in only 8 (57%) patients in group 2 (p<0.01) There was no significant difference in the extent of underlying coronary artery disease between the two groups. Retrograde filling by collateral flow to the infarct-related artery was significantly better in group 1 compared to group 2 (p<0.02). Although wall motion abnormality score was significantly higher in group 1 compared to group 2 (4.6±1.8 vs. 3.1±1.2, p<0.02), no patient had left ventricular aneurysm. These results suggest that even if segmental wall motion is severely abnormal, exercise-induced ST elevation in recent Q wave MI is related to myocardial viability.