It is unclear whether pathologic Q waves on ECG always correlate with ischemic patterns in MRI of the heart. In the classic ECG, a Q wave is an indication of myocardial infarction. If the Q wave is large, it may be an indication of a large amount of dead myocardial tissue. The size and shape of the Q wave depend on the location and severity of the infarct.
The Q wave represents the direction of the electrical impulse as it travels through the heart muscle. Pathologic Q waves are usually seen on an electrocardiogram (ECG) when there is myocardial infarction (heart attack).
