This electrocardiogram shows an acute extensive anterolateral wall myocardial infarction in evolution. The characteristic features demonstrated here include ST-segment elevations in the anterior precordial leads V2 through V6 and in limb lead I. Q waves are present in V1 through V3. The ST-segment elevations will in most cases return to the baseline as the infarction evolves. While the Q waves remain as the marker of dead tissue. In cases of left ventricular aneurysm, the ST-segment elevations may remain.