RT-48
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Specificity of T-wave alternans
in individuals without organic heart disease who are not inducible during ventricular
programmed stimulation
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Hans D. Esperer, Antonis A.
Armoundas, David S. Rosenbaum*, Helmut U. Klein**, Richard J. Cohen.
Harvard University, MIT Division of Health Sciences and Technology, Cambridge, *Case
Western Reserve University, Cleveland, USA, **University Hospital, Division of Cardiology,
Otto-von-Guericke University, Magdeburg, Germany
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Abstract
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Background. Microvolt-level T-wave
alternans (TWA) has been shown to predict accurately potentially lethal ventricular
tachy-arrhythmias in patients with organic heart disease. The aim of this study was to
investigate the specificity of TWA regarding prediction of ventricular dysrhythmias in
patients without structural heart disease.
Methods. We retrospectively analyzed data of patients without organic
heart disease who had undergone electrophysiologic testing (EPS) for workup of syncope,
presyncope or WPW syndrome. Twelve patients (5 females) aged 37 ± 13 years (range: 16-55
ys) were included. Prior to EPS, each patient was off of any antiarrhythmic medication for
at least five half lives of the respective antiarrhythmic drugs. TWA was determined during
atrial pacing prior to EPS. TWA spectrum was calculated using fast Fourier transform
analysis and TWA was expressed as the alternans ratio: K = (alternans peak-meannoise)/SDnoise.
A K value > 3.0 was considered a positive TWA result.
Results. EPS revealed the presence of accessory pathways (n = 7),
typical AV nodal reentry tachycardia (n = 2), and intraatrial reentry tachycardia (n = 1).
In 2 patients no supraventricular tachyarrhythmia was inducible. Of note, in none of the
patients, ventricular tachyarrhythmias were inducible during programmed ventricular
stimulation (PS). TWA was positive (K = 22.0) in one patient with a left lateral and a
right lateral accessory bypass tract. This might have been a false-positive result due to
cardiac memory associated with abnormal spread of cardiac excitation. Thus, overall
specificity of TWA in predicting the outcome of PS in this poupulation was 83.3%.
Conclusions. In this patient population, including preexcitation
syndromes, TWA was a highly specific method in individuals with structurally normal hearts
who are not inducible during PS.
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Key Words
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T-wave interval
programmed ventricular stimulation, ventricular tachyarrhythmias, OA
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