Microvolt-level T-wave alternans determination using the spectral method in patients with QT prolongation: value of adjusting the T-wave window

• Published in: Journal of electrocardiology 2012-11, Vol.45 (6), p.758-763
• Main Authors: Kaufman, Elizabeth S., MD, Lewis, Steven A., MS, Leo, Peter, RN, Aswath, Ganesh, MD, Ziv, Ohad, MD, Fendelander, Lahn, MS
• Format: Article
• Language: English
• Subjects: Adult; Algorithms; Cardiovascular; Diagnosis, Computer-Assisted - methods; Electrocardiography - methods; Female; Humans; Long QT Syndrome - diagnosis; Long-QT syndrome; Male; Pattern Recognition, Automated - methods; QT prolongation; Reproducibility of Results; Sensitivity and Specificity; Spectral method; Sudden cardiac death; T-wave alternans
• ISSN: 0022-0736; 1532-8430
• DOI: 10.1016/j.jelectrocard.2012.07.007

Abstract Background Microvolt-level T-wave alternans (MTWA) measured by the spectral method is a useful risk predictor for sudden cardiac death because of its high negative predictive value. MTWA analysis software selects a segment of the ECG that encompasses the T-wave in most individuals, but may miss the T-wave end in patients with QT prolongation. Hypotheses (1) In patients with QT prolongation, adjustment of the T-wave window will increase the sensitivity of MTWA detection. (2) The extent of T-wave window adjustment needed will correspond to the degree of QT prolongation. Methods Using data from long-QT syndrome patients, including QTc < 0.45s (normal), 0.45–0.49s (moderate prolongation), and ≥ 0.50s (severe prolongation), MTWA analysis was performed before and after T-wave window adjustment. Results Of 119 patients, 74% required T-wave window adjustment. There was a stronger association between the magnitude of the T-wave offset and the unadjusted QT than between the magnitude of the T-wave offset and QTc (Spearman correlation coefficient 0.690 vs. 0.485 respectively, P