The electrophysiologic continuum of occlusion myocardial infarction

Acute coronary syndromes used to be classified according to the presence or absence of ST elevation (ST Elevation Myocardial Infarction, STEMI and Non ST Elevation Myocardial Infarction, NSTEMI). The latter contained STEMI-equivalents, indicating severe ischemia in the setting of critical stenoses in the coronary arteries. To combine both STEMI and STEMI equivalent patterns a new term was coined, i.e. occlusion myocardial infarction (OMI). OMI contains also more recently recognized patterns, among others the Aslanger pattern, South African flag pattern, precordial swirl sign, Northern pattern. Memorizing independent ECG patterns however is difficult and understanding the pathophysiology, leading to ischemic ECG changes, may be more helpful in recognizing acute ischemic syndromes. In the following a unifying system is proposed, combining the different ECG expressions of acute coronary syndromes. It is based on the concept of transmural (endo to epicardial) voltage differences and of the vectorial properties of the electrical activity of the heart. It is realized that the model of the ventricular gradient and ST vector changes during myocardial ischemia, as presented here, is a simplification and will not cover all aspects of the electrical phenomenology in myocardial ischemia and all reported OMI presentations, Nevertheless it may provide a theoretical framework that grounds the OMI concept, and a better oversight of the different ST-T presentations of acute ischemic syndromes.