T wave alternans in idiopathic long QT syndrome

Department of Preventive and Community Medicine, University of Rochester School of Medicine and Dentistry, New York.

OBJECTIVES. The study evaluates the association between T wave alternans and the risk of cardiac events (syncope, aborted cardiac arrest or cardiac death) in a large population of patients with idiopathic long QT syndrome. BACKGROUND. T wave alternans is an infrequently recorded electrocardiographic (ECG) finding in patients with delayed repolarization, and its clinical significance is not clear. METHODS. A total of 4,656 ECG recordings in 2,442 patients enrolled in the International Long QT Syndrome Registry were reviewed for episodes of T wave alternans. To determine the risk associated with T wave alternans, independent of corrected QT interval (QTc) duration, patients with T wave alternans were matched for QTc value (every 0.025 s1/2) to patients with long QT syndrome without T wave alternans. RESULTS. T wave alternans was identified in 30 patients (25 of whom had a QTc interval > 0.50 s1/2). A strong association between QTc prolongation and T wave alternans was observed (odds ratio 1.23 per 0.01-s1/2 unit increase in QTc, p < 0.0001). Conditional logistic regression analyses with adjustment for age, gender, status and QTc value revealed that T wave alternans did not make a significant independent contribution to the risk of cardiac events. The risk of experiencing a major cardiac event was primarily related to length of QTc. CONCLUSIONS. T wave alternans, a marker of electrical instability and regional heterogeneity of repolarization, identifies a high risk subset of patients with prolonged repolarization. Patients with T wave alternans have an increased risk of cardiac events, but this risk is primarily related to the magnitude of repolarization delay (QTc prolongation). T wave alternans does not make an independent contribution to the risk of cardiac events after adjustment for QTc length.

This article has been cited by other articles:

				G. Thomas, M. J. Killeen, I. S. Gurung, P. Hakim, R. Balasubramaniam, C. A. Goddard, A. A. Grace, and C. L.-H. Huang Mechanisms of ventricular arrhythmogenesis in mice following targeted disruption of KCNE1 modelling long QT syndrome 5 J. Physiol., January 1, 2007; 578(1): 99 - 114. [Abstract] [Full Text] [PDF]

				H. Morita, D. P. Zipes, J. Lopshire, S. T. Morita, and J. Wu T wave alternans in an in vitro canine tissue model of Brugada syndrome Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H421 - H428. [Abstract] [Full Text] [PDF]

				H. Morita, S. T. Morita, S. Nagase, K. Banba, N. Nishii, Y. Tani, A. Watanabe, K. Nakamura, K. F. Kusano, T. Emori, et al. Ventricular arrhythmia induced by sodium channel blocker in patients with Brugada syndrome J. Am. Coll. Cardiol., November 5, 2003; 42(9): 1624 - 1631. [Abstract] [Full Text] [PDF]

				A. A. Armoundas, G. F. Tomaselli, and H. D. Esperer Pathophysiological basis and clinical application of T-wave alternans J. Am. Coll. Cardiol., July 17, 2002; 40(2): 207 - 217. [Abstract] [Full Text] [PDF]

				S.G. Priori, E. Aliot, C. Blomstrom-Lundqvist, L. Bossaert, G. Breithardt, P. Brugada, A.J. Camm, R. Cappato, S.M. Cobbe, C. Di Mario, et al. Task Force on Sudden Cardiac Death of the European Society of Cardiology Eur. Heart J., August 2, 2001; 22(16): 1374 - 1450. [PDF]

				D. S. Goldman, W. Zareba, and A. J. Moss Malignant T-Wave Alternans Circulation, August 22, 2000; 102 (8): e46 - e47. [Full Text] [PDF]

				F. E. S. Cruz Filho, I. G. Maia, M.a. L. A. Fagundes, R. C. P. Barbosa, P. A. G. Alves, R. M. S. Sa, S. H. Boghossian, and J. C. Ribeiro Electrical behavior of T-Wave polarity alternans in patients with congenital long QT syndrome J. Am. Coll. Cardiol., July 1, 2000; 36(1): 167 - 173. [Abstract] [Full Text] [PDF]

				T. Ikeda, T. Sakata, M. Takami, N. Kondo, N. Tezuka, T. Nakae, M. Noro, Y. Enjoji, R. Abe, K. Sugi, et al. Combined assessment of T-wave alternans and late potentials used to predict arrhythmic events after myocardial infarction: A prospective study J. Am. Coll. Cardiol., March 1, 2000; 35(3): 722 - 730. [Abstract] [Full Text] [PDF]

				Y Fujimoto, H Morita, K K Fukushima, and T Ohe Nicorandil abolished repolarisation alternans in a patient with idiopathic long QT syndrome Heart, November 1, 1999; 82(5): 8e - 8. [Abstract] [Full Text]

				W. Shimizu and C. Antzelevitch Cellular and Ionic Basis for T-Wave Alternans Under Long-QT Conditions Circulation, March 23, 1999; 99(11): 1499 - 1507. [Abstract] [Full Text] [PDF]

				H L Tan and A A M Wilde T wave alternans after sotalol: evidence for increased sensitivity to sotalol after conversion from atrial fibrillation to sinus rhythm Heart, September 1, 1998; 80(3): 303 - 306. [Abstract] [Full Text]

				S. Sicouri, S. Moro, and M. V. Elizari d-Sotalol Induces Marked Action Potential Prolongation and Early Afterdepolarizations in M but Not Epicardial or Endocardial Cells of the Canine Ventricle Journal of Cardiovascular Pharmacology and Therapeutics, January 1, 1997; 2(1): 27 - 37. [Abstract] [PDF]

				D. M. Roden, R. Lazzara, M. Rosen, P. J. Schwartz, J. Towbin, and G. M. Vincent Multiple Mechanisms in the Long-QT Syndrome: Current Knowledge, Gaps, and Future Directions Circulation, October 15, 1996; 94(8): 1996 - 2012. [Abstract] [Full Text]

				A. A. Grace and K. R. Chien Congenital Long QT Syndromes : Toward Molecular Dissection of Arrhythmia Substrates Circulation, November 15, 1995; 92(10): 2786 - 2789. [Full Text]