[Transmural myocardial infarction. An impossible electrocardiographic diagnosis]

The anatomical and experimental data clearly show that transmural myocardial infarction does not always produce a pathological Q wave on the ECG, but may sometimes only cause abnormalities of the ST segment and the T wave. Conversely, a sub-endocardial myocardial infarction may present with pathological Q waves. Schematically, the histology of transmural myocardial infarction usually reveals so-called coagulation necrosis, while sub-endocardial myocardial infarction generally corresponds to myofibrillary degeneration (contraction band necrosis), which promotes a reperfusion process. Very often, however, the histological appearance is not so clear-cut and the features tend to overlap. Consequently, in practice, it does not seem justified to use the electrocardiogram as a basis to distinguish between transmural and sub-endocardial infarctions, in terms of prognosis, or to select possible candidates for coronary angiography following a first myocardial infarction.