QT variability index in patients with systemic sclerosis.

Systemic sclerosis (SSc) may affect the heart with microvascular dysfunction and lead to an early cardiac death, but the association between certain repolarization indexes and SSc heart disease remains controversial. Our goal was to evaluate a previously unstudied marker of repolarization dynamics, i.e., QT variability, in patients with SSc and to assess its prognostic implications. A total of 17 patients with SSc and 21 healthy controls were included into this prospective study. Electrocardiograms were conducted under strict standards. The QT variability index (QTVI), normalized QT variability (QTVN), and power spectral analysis of QT dynamics, considered as markers of ventricular arrhythmias in a number of other disorders, were determined using designated computer software. There was no significant difference in demographic and cardiac important clinical parameters between the groups. Also, the mean QTVI, QTVN, and power spectral analysis parameters were comparable between the patients with SSc and control subjects. At baseline, the QTVI values of 1 patient with SSc, who experienced ventricular arrhythmia prior to inclusion in the study, were considerably higher compared to other patients with SSc. None of the remaining patients with SSc or the control subjects developed arrhythmia during the follow-up of 8 years. Higher than normal QTVI may be found in the minority of patients with SSc. The prognostic significance of this finding is unknown, but it may entail an increased risk of ventricular arrhythmias. Therefore, the value of QTVI as a tool for arrhythmia risk stratification in SSc merits further research.