An electrocardiogram (EKG) may detect a heart attack. ` Strictly speaking, the EKG of a patient with a myocardial infarction has a blip called a Q-wave. The age of the heart is determined by the ST and T waves. An acute heart attack (< 24 hours old) demonstrates ST and T-wave elevation. A recent heart attack (24-48 hours old) show some ST segment elevation and T-wave inversion. Age-undetermined heart attacks (48 hours to months-old) display baseline ST segments, but inverted or flat T-waves. Finally, an old myocardial infarction (months to years-old) exhibits Q-waves with normal ST and T waves. Heart attacks can also be divided into two groups – STEMI and non-STEMI. The first, ST segment Elevation Myocardial Infarction, presents with elevated ST segments on the EKG of a patient with cardiac-type chest pain. The second, non-ST segment Elevation Myocardial Infarction does not have these obvious ST segment changes and is recognized by identifying the patient’s symptoms and abnormal cardiac enzymes (blood tests)