Lack of difference in T wave variability between patients at risk of sudden cardiac death and healthy subjects.
BACKGROUND
T wave variability (Tvar) is a proposed method to predict sudden cardiac death (SCD). The purpose of this trial was to evaluate the reproducibility of Tvar measurements over time and demonstrate a difference in Tvar between patient populations at risk for ventricular arrhythmias and healthy subjects.


METHODS
Sixty subjects were enrolled in into 3 groups: healthy subjects (Population I), patients at high risk of SCD (Population II), and patients with a recent ventricular tachyarrhythmia event (Population III). Recording and analysis of T wave amplitude variance (TAV) as a measure of Tvar was performed at baseline and 3 months.


RESULTS
TAV could not be interpreted in 12 of 43 patients in Populations II and III due to PVCs or noise. No subject had a TAV value suggestive of high risk of SCD as per a previously defined cutoff of >59 μV. Median (range) values of TAV in μV at baseline for Populations I, II and III were 26 (15-39), 21 (13-43), and 24 (18-41), respectively (p = 0.39). TAV was reproducible within population's from baseline to 3 months (p = 0.27, 0.53, 0.17 for Populations I, II and III, respectively). There was no significant difference between TAV values of high risk patients and healthy subjects.


CONCLUSIONS
Tvar was reproducible primarily in patients with left ventricular dysfunction. However, the role of Tvar as a risk stratifying tool remains inconclusive.
St Michael's Hospital, University of Toronto, Toronto, Canada.
Kevin
K
Levitt
St Michael's Hospital, University of Toronto, Toronto, Canada.
Theresa
T
Aves
St Michael's Hospital, University of Toronto, Toronto, Canada.
Paul
P
Dorian
St Michael's Hospital, University of Toronto, Toronto, Canada. Electronic address: pintera@smh.ca.
Arnold
A
Pinter
D000328:Adult; D016022:Case-Control Studies; D016757:Death, Sudden, Cardiac; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors
Cardiac repolarization; Noninvasive risk stratification; T wave variability