926–25 Arrhythmogenic T Wave Alternans is Primarily a Disturbance of Early Repolarization

• Published in: Journal of the American College of Cardiology 1995-02, Vol.25 (2), p.107A-108A
• Main Authors: Vijgen, Johan M., Julka, Birendra, Rosenbaum, David S.
• Format: Article
• Language: English
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/0735-1097(95)91899-9

Although we have shown previously that electrical alternans of the ST segment and T wave; i.e., repolarization alternans (RA), is a marker of vulnerability to ventricular arrhythmias, the mechanism of RA in humans remains unclear. To determine the component of repolarization that is most closely associated with arrhythmogenesis, electrical alternans of the ST segment, and the early (Tearly), mid (Tmid), and late (Tlate) components of the T wave were measured using sensitive spectral analytical techniques in 35 patients undergoing electrophysiological studies (EPS). Alternans measured in each phase of repolarization was correlated with arrhythmia vulnerability as defined by; 1. The results of EPS and 2. Actuarial 20 month arrhythmia-free survival. [Display omitted] In EPS+ patients, the magnitude of RA increased progressively during later phases of repolarization (Figure). In contrast, EPS-patients had elevated RA levels only in late (Tlate) but not during early repolarization. Hence, RA of Tlatedid not differ significantly between EPS + and EPS–patients (Figure). Inducibility at EPS was predicted with greatest specificity by the presence of RA in early repolarization (TearlySpecificity = 0.88), compared to RA involving later components of the T wave; Tmid(0.79). Tlate(0.63). or the ST segment (0.71). Similarly, RA involving early repolarization was the most specific marker for reduced arrhythmia-free survival (Specificity's: Tearly0.87, Tmid0.83, Tlate0.58, ST 0.80). RA of the terminal component of the T wave is present in most patients and is not necessarily a specific marker for arrhythmia vulnerability. In contrast, RA involving the early phases of repolarization (Tearly) appears 10 have the most prognostic significance. RA related arrhythmogenesis may be due to an underlying disturbance affecting early repolarization.