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.

CONCLUSION: Tvar was reproducible primarily in patients with left ventricular dysfunction. However, the role of Tvar as a risk stratifying tool remains inconclusive.