Microvolt-level T-wave Alternans Determination Using the Spectral Method in Patients with QT Prolongation: Value of Adjusting the T-wave Window

Overview

Journal J Electrocardiol

Specialty Cardiology & Vascular Diseases

Date 2012 Sep 11

PMID 22960166

Authors

Elizabeth S Kaufman

Steven A Lewis

Peter Leo

Ganesh Aswath

Ohad Ziv

Lahn Fendelander

Affiliations

Soon will be listed here.

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 <0.45 s (normal), 0.45-0.49 s (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<.05). Of 99 initially negative MTWA results, 4 became non-negative after adjustment of the T-wave window (P<.05). All 8 initially positive studies and 12 initially indeterminate studies remained positive and indeterminate, respectively.

Conclusions: T-wave window adjustment can enable detection of abnormal MTWA that otherwise would be classified as "negative" or "normal." Newly developed T-wave window adjustment software may further improve the negative predictive value of MTWA testing and should be validated in a structural heart disease population.

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