Stress-induced ST-segment elevation following myocardial infarction and its role in wall motion abnormality, myocardial ischemia and viability - Comparison of response to exercise, dobutamine and dipyridamole

Stress-induced ST-segment elevation following myocardial infarction (MI) ha s been correlated with myocardial ischemia, viability and wall motion abnor mality, but its mechanism is still unclear, so the present study compared S T-segment elevation and wall motion response during exercise, dobutamine an d dipyridamole stresses. Twenty-five patients with their first anterior MI underwent exercise, dobutamine and dipyridamole echocardiography on differe nt days 4-6 weeks after MI. Left ventricular wall motion was analyzed using 5-grade/16-segment model and myocardial ischemia was considered as a worse ning of the wall motion score index (WMSI) during the stress test; myocardi al viability was defined as a reduction of WMSI during low dose dobutamine. Dyskinesis formation was defined by visual analysis as akinesis that becam e dyskinetic or if the dyskinesis worsened. Both exercise and dobutamine in duced ST-segment elevation, but dipyridamole did not. There was no signific ant difference in the degree of ST-segment elevation between the patients w ith and without myocardial ischemia or dyskinesis formation. Exercise induc ed a higher ST-segment elevation in patients with myocardial viability than those without (0.17 +/-0.09 mV vs 0.09 +/-0.07 mV, p <0.05). Exercise-indu ced ST-segment elevations correlated with dobutamine-induced ST-segment ele vations (p <0.01), changes in heart rate (p <0.05) and systolic blood press ure (p <0.05). In conclusions, stress-induced ST-segment elevation does not correlate with either myocardial ischemia or stress-induced dyskinesis, bu t may be associated with myocardial viability.