The significance of the subendocardial infarction.

Myocardial infarction without the development of Q waves on ECG should be labeled "non-Q-wave" rather than "subendocardial." The non-Q-wave infarction has doubtful significance in the patient with a prior myocardial infarction. However, as the first myocardial infarction, it is associated with lesser degrees of coronary artery disease and left ventricular dysfunction. It usually represents a smaller area of infarction, and it carries a favorable prognosis, especially in patients under 60.