Role of myocardial ischemia and left ventricular wall motion abnormalitiesas contributory factors in the genesis of exercise-induced ST-segment elevation in Q-wave myocardial infarction

In patients with a previous myocardial infarction, controversy exists regar ding the significance of postexercise ST-segment elevation in the infarct-r elated leads. Although usually admitted to be a sign of left ventricular dy sfunction or myocardial aneurysm, other studies however have related this f inding to transient myocardial ischemia and to the presence of jeopardized but viable myocardium in the infarct area. The aim of the present study was to assess the significance of postexercise ST-segment elevation in Q-wave leads as a marker of transmural ischemia or left ventricular dysfunction in 36 consecutive patients, 16 with exercise-induced ST-segment elevation in infarct-related leads. Patients were evaluated by treadmill exercise testin g, coronary angiography and ventriculography, thallium-201 tomographic scin tigraphy and radionuclide ventriculography within 3 months of the first myo cardial infarction. Sixteen patients (group I) had exercise-induced Si segm ent elevation and 20 (group II) postexercise inversion, no change or pseudo normalization of the T wave in infarct-related leads. The study showed no d ifference in infarct-related artery, vessel disease or luminal diameter ste nosis in groups I and II. The overall agreement between ST shifts and myoca rdial perfusion in the infarct area was 30.56% with a kappa. coefficient of -0.33 (p = NS). The overall agreement between ST shifts and wall motion ab normalities was 69.44% with a kappa coefficient of 0.39 (p < 0.01), stress- induced ST-segment elevation being associated with severe wall contractile disorders in 85% of the patients. In conclusion stress-induced ST-segment e levation in Q wave leads, although not a marker of wall motion abnormalitie s, is associated with akinesia or dyskinesia of the left ventricular wall.