67. Microvolt T-wave Alternans

  1. Mohammad Shenasa MD2,
  2. Gerhard Hindricks MD3,
  3. Martin Borggrefe MD4,
  4. Günter Breithardt MD5 and
  5. Mark E. Josephson MD6
  1. Levent Sahiner and
  2. Ali Oto

Published Online: 18 DEC 2012

DOI: 10.1002/9781118481585.ch67

Cardiac Mapping, Fourth Edition

Cardiac Mapping, Fourth Edition

How to Cite

Sahiner, L. and Oto, A. (2013) Microvolt T-wave Alternans, in Cardiac Mapping, Fourth Edition (eds M. Shenasa, G. Hindricks, M. Borggrefe, G. Breithardt and M. E. Josephson), Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781118481585.ch67

Editor Information

  1. 2

    Attending Physician, Department of Cardiovascular Services, O'Connor Hospital, Heart & Rhythm Medical Group, San Jose, California, USA

  2. 3

    Professor of Medicine (Cardiology), University Leipzig, Heart Center, Director, Department of Electrophysiology, Leipzig, Germany

  3. 4

    Professor of Medicine (Cardiology), Head, Department of Cardiology, Angiology and Pneumology, University Medical Center, Mannheim Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany

  4. 5

    Professor Emeritus of Medicine and Cardiology, Department of Cardiology and Angiology, Hospital of the University of Münster, Münster, Germany

  5. 6

    Chief, Cardiovascular Medicine Division, Director, Harvard-Thorndike Electrophysiology Institute and Arrhythmia Service, Beth Israel Deaconess Medical Center, Herman C. Dana Professor of Medicine, Harvard Medical School, Boston, Massachusetts, USA

Author Information

  1. Hacettepe University Faculty of Medicine, Ankara, Turkey

Publication History

  1. Published Online: 18 DEC 2012
  2. Published Print: 10 JAN 2013

ISBN Information

Print ISBN: 9780470670460

Online ISBN: 9781118481585



  • T-wave alternans;
  • surface electrocardiogram;
  • ventricular arrhythmias;
  • macroscopic alternans;
  • ventricular tachycardia;
  • sudden cardiac death;
  • implantable cardioverter-defibrillator therapy;
  • left ventricular ejection fraction


T-wave alternans (TWA) is defined as a 2:1 fluctuation (repeating ABABAB… pattern) in the shape and amplitude of the T-wave. As macroscopic alternans is a rare event to observe; sophisticated computerized analysis techniques have been developed to detect alternations at microvolt level in T-wave (MTWA) which is invisible in the surface ECG. Since the first introduction of the MTWA assessment by computerized techniques, a substantial amount of evidence has linked this repolarization parameter with the risk of life-threatening ventricular arrhythmias. In this chapter the mechanisms underlying TWA, technical and methodological aspects of the MTWA assessment and its clinical implications are reviewed.