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Determinant of microvolt-level T-wave alternans in patients with dilated cardiomyopathy
1First Department of Internal Medicine, Kobe University School of Medicine, Japan.
Objectives:
The aim of this study was to clarify the clinical significance and the determinant of microvolt-level T-wave alternans (TWA) in patients with dilated cardiomyopathy (DCM).
Background:
The prevention of sudden death in patients with DCM remains the therapeutic target. T-wave alternans has been proposed as a powerful tool for identification of patients at high risk for ventricular arrhythmias and sudden death in coronary artery disease.
Methods:
In 58 DCM patients, TWA was measured during bicycle exercise testing using a CH 2000 system (Cambridge Heart, Bedford, Massachusetts). The New York Heart Association class, signal-averaged electrocardiogram, QT dispersion, left ventricular end-diastolic diameter (LVDd) and percent fractional shortening detected by echocardiogram and the grade of the ventricular arrhythmia were obtained in all patients.
Results:
T-wave alternans was positive in 23 patients (TWA+ group), negative in 25 (TWA- group) and indeterminate in 10. Univariate analysis showed that the percentage of patients with ventricular tachycardia (VT) and the LVDd in the TWA+ group was significantly higher than those in the TWA- group (61% vs. 8%, p < 0.001 and 65 +/- 11 mm vs. 58 +/- 8 mm, p < 0.05, respectively). The sensitivity, specificity and predictive accuracy of TWA for VT were 88%, 72% and 77%, respectively. Multivariate analysis showed that the presence of VT was a major independent determinant of TWA in patients with DCM (p = 0.003).
Conclusions:
T-wave alternans was closely related to VT in patients with DCM. T-wave alternans is a useful noninvasive test for identifying high risk patients with DCM who have VT.