Microvolt T-wave alternans: a review of techniques, interpretation, utility, clinical studies, and future perspectives.
Microvolt T-wave alternans (TWA) testing involves measuring variation in the morphology of the T-wave on an every other beat basis. The magnitude of the variation observed is typically on the order of a few microvolts. Thus in order to detect microvolt TWA, specialized recording and signal processing methods must be employed for reliable measurement. Additionally, microvolt TWA is not generally present at rest even in patients at risk of ventricular tachyarrhythmias and therefore exercise stress, pharmacologic stress, or atrial pacing must be utilized in order to elevate the heart rate. A positive MTWA test is one in which sustained TWA is present with an onset heart rate < or = 110 bpm. With current instrumentation, microvolt TWA represents an inexpensive, convenient non-invasive testing modality. Microvolt TWA has been evaluated prospectively in a variety of patient populations as a means of predicting occurrence of ventricular tachyarrhythmic events and its association with the genesis of ventricular arrhythmias has been demonstrated. Future role of microvolt TWA testing in noninvasive risk stratification is awaiting results of ongoing clinical trials. In this article, we tried to review the techniques, interpretation, indications, clinical studies, and future perspectives of microvolt TWA.
Haghjoo
Majid
M
Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Medical and Research Center, School of Medicine, Iran University of Medical Sciences, Mellat Park, Vali-e-Asr Avenue, P.O. Box 15745-1341, Tehran 1996911151, Iran. majid.haghjoo@gmail.com
Arya
Arash
A
Sadr-Ameli
Mohammad Ali
MA
D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D015415:Biomarkers; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology; D004562:Electrocardiography / Q000187:drug effects / Q000379:methods*; D006339:Heart Rate; D006801:Humans; D013564:Sympathetic Nervous System / Q000502:physiology; D014693:Ventricular Fibrillation / Q000503:physiopathology
D000889:Anti-Arrhythmia Agents; D015415:Biomarkers