Interpretation of acute myocardial infarction with persistent 'hyperacute T waves' by cardiac magnetic resonance.

Peaked and tall T waves represent a hyperacute electrocardiogram (ECG) manifestation of coronary artery occlusion which usually evolves into ST-segment elevation. We sought to investigate using cardiac magnetic resonance (CMR) the myocardial tissue changes underlying an atypical ECG pattern of presentation of left anterior descending artery (LAD) occlusion consisting of persistent hyperacute T waves and mild ST-segment depression. This ECG pattern is often associated with the presence of collateral circulation, which may modulate myocyte action potential changes in response to ischemia and prevent the appearance of ST-segment elevation. However, CMR findings resembled those of typical anterior myocardial infarction with nearly transmural necrosis in the large myocardial area supplied by LAD. Accordingly, persistent hyperacute T waves should be regarded as an equivalent to ST-segment elevation and immediate reperfusion therapy should be considered.