Terminology and diagnostic criteria for non-Q wave myocardial infarct

Abstract

Non-Q myocardial infarction represents a specific entity of infarction. Many studies have shown that non-Q myocardial infarction differs from Q myocardial infarction not only electrocardiographically, but also from pathophysiological, histological, clinical and prognostic points of view. NON-Q MYOCARDIAL INFARCTION-TERMINOLOGY: Until 1980's, anatomical terminology depending on ECG changes was used in the literature. Subendocardial infarction referred to non-Q myocardial infarction, while transmural infarction referred to Q myocardial infarction. Since it was established that presence or absence of Q waves is a non-specific marker of transmural necrosis, in 1982 Spodick proposed the use of terms based on ECG findings. DIAGNOSTIC CRITERIA FOR NON-Q MYOCARDIAL INFARCTION: Elevation of markers of myocardial damage (CK, CK-MB, Troponin) is the most significant criterion for diagnosis of non-Q myocardial infarction. It cannot be made without this criterion because non-Q myocardial infarction may have ECG changes identical to those in unstable angina. Authors do not agree which type of initial ECG changes is the most frequent (ST elevation, ST depression or inverted T waves). Non-Q myocardial infarction represents a specific entity of myocardial infarction. Anatomically, based on the extension of necrosis, non-Q myocardial infarction is subendocardial, but it can be transmural as well. ECG changes in non-Q myocardial infarction may be identical to those in unstable angina. Therefore, elevation of cardiac enzymes is the golden standard in diagnosis of non-Q myocardial infarction.