Acute anterior wall myocardial infarction presenting with positive T waves and without ST segment shift. Electrocardiographic features and angiographic correlation.

Eighteen patients with a first AMI, who during the acute ischemic phase did not develop ST segment elevation, but only positive or peaked T waves, are described. Patients who do not develop ST segment elevation during evolving anterior AMI represent a subgroup with a high probability of total obstruction of the LAD artery with retrograde filling via collateral vessels and a small degree of left ventricular dysfunction. We assume that during the period of total obstruction there was preexisting adequate collateral circulation in order to prevent transmural ischemia, which explains the absence of ST segment elevation.