1. Normal sinus rhythm
2. Ventricular couplets
3. T wave alternans
T wave alternans refers to the variation of the T wave amplitude on an ECG on a beat-to-beat basis. Having significant T wave alternans is thought to increase the risk of ventricular arrhythmias and sudden cardiac death. This ECG shows T wave alternans in lead V1. T wave alternans is categorized as "macro" as seen on this ECG or "micro" which is difficult to detect with the naked eye.
Microvolt T wave alternans is a test allowing the detection of very small changes in the T wave amplitude and is currently the standard method to evaluated for T wave alternans. The test is reported as positive, negative or indeterminate. The clinical usefulness of T wave alternans is not clear. Identifying patients at high risk for ventricular arrhythmia after myocardial infarction in order to insert an implantable cardioverter defibrillator (ICD) is a possible use of T wave alternans. A high negative predictive value has been seen with the T wave alternans test. There have been four clinical trials evaluating the usefulness of T wave alternans including the ALPHA Trial, ABCD trial, REFINE trial and the MASTER trial. See LearnTheHeart.com's clinical trial section for more details.
