Lack of noninvasive markers of ventricular repolarization inhomogeneity inpatients with idiopathic ventricular tachyarrhythmia

Noninvasive markers reflecting repolarization. inhomogeneity have been prop osed to be useful indices for identifying patients at risk of ventricular a rrhythmias based on organic heart disease. In this study, we clarify whethe r or not repolarization inhomogeneity markers are useful in patients with i diopathic ventricular tachycardia (VT). We investigated T-wave alternans (T WA) and corrected QT-interval dispersion (QTD) in 84 consecutive patients w ith idiopathic VT, 90 patients with VT associated with organic heart diseas e (organic VT), and 87 normal individuals. VT was defined as tachycardia la sting greater than or equal to5 consecutive ventricular ectopic beats at a rate of greater than or equal to 120 beats/min. TWA was positive in 20 of 8 4 patients (24%) with idiopathic VT, 59 of 90 patients (66%) with organic V T, and 16 of 87 normal individuals (18%). The alternans voltage was 2.6 +/- 3.1 mu V in idiopathic VT patients, 5.6 +/-6.4 mu V in organic VT patients, and 2.9 +/-5.7 mu V in normal individuals. QTD were 53 +/- 20 ms in idiopa thic VT patients, 92 +/- 20 Ins in organic VT patients, 46 +/- 18 ms in nor mal individuals, respectively. A positive TWA test result was seen more (P< .01) frequently, and QTD was longer (P<.01) in organic VT patients compared to normal individuals, whereas there was no difference between idiopathic VT patients and normal individuals. In addition, in patients with idiopathi c VT, neither did any of these measurements differ between patients with su stained VT (lasting for greater than or equal to 30 s) and those with nonsu stained VT. Noninvasive markers of repolarization inhomogeneity, such as TW A and QTD, are not useful for identifying patients with idiopathic VT. Repo larization inhomogeneity may not affect to the pathogenesis of idiopathic V T.