Within seconds two minutes of vessel occlusion, symmetrical peaked T-waves are observed in the leads directly overlying the blood deprived area of myocardium.
Whatever the mechanism generating the phenomenon, ST-segment elevation on an ECG is the hallmark of evolving myocardial infarction secondary to complete occlusion of a coronary artery of vessel.
If such an episode of partial occlusion resolves with no infract developing in the ischemic area, the patient is said to have suffered an episode of unstable angina.
Unlike infarction secondary to complete vessel occlusion, ST elevation is not observed on the ECG, also as much of the myocardial wall under the lead remains viable and actively depolarizing.
Ischemia in the areas supplied by the partially occluded vessel illustrated here in the lateral wall of the left ventricle is primarily targeted on the sub endocardial aspect of the affected region.