A transmural myocardial infarction refers to a myocardial infarction that involves the full thickness of the myocardium. It was one believed that the development of Q waves indicated the infarction was “transmural;” however, autopsy studies failed to confirm this. A “non-transmural” MI is one that does not involve the full thickness of the myocardium. The terms Q wave MI, non-Q wave MI, transmural MI and non-transmural MI are no longer recommended for use. Instead, acute coronary syndromes are classified as unstable angina, non-ST elevation MI and ST elevation MI.