The T wave occurs after the QRS complex and is a result of ventricular repolarization.
T waves should be upright in most leads; the exceptions are aVR and V1. Further, T waves should be asymmetric in nature. The second portion of the T wave should have a steeper decline when compared with the incline of the first portion. If the T wave appears symmetric, cardiac pathology such as ischemia may be present.
Many abnormal T wave patterns exist and are reviewed in more detail in the relevant ECG Reviews and Criteria sections. These include hyperkalemia, Wellens’ syndrome, left ventricular hypertrophy with repolarization abnormalities, pericarditis (stage III), arrhythmogenic right ventricular dysplasia or ARVD, and hyperacute T waves during myocardial infarction.