QT and JT dispersion and cardiac performance in children with neonatal Bartter syndrome: a pilot study.

BACKGROUND: QT dispersion and JT dispersion are simple noninvasive arrhythmogenic markers that can be used to assess the homogeneity of cardiac repolarization. The aim of this study was to assess QT and JT dispersion and their relation with left ventricular systolic and diastolic functions in children with Bartter syndrome (BS).

METHODS: Nine neonatal patients with BS (median age 9.7 years) and 20 controls (median age 8 years) were investigated at rest. Both study and control subjects underwent electrocardiography (ECG) in which the interval between two R waves and QT intervals, corrected QT, QT dispersion, corrected QT dispersion, JT, corrected JT, JT dispersion and corrected JT dispersion were measured with 12-lead ECG. Two-dimensional, Doppler echocardiographic examinations were performed.

RESULTS: Patients and controls did not differ for gender and for serum levels of potassium, magnesium, and calcium (p > 0.05). Both study and control subjects had normal echocardiographic examination and baseline myocardial performance indexes. The QT dispersion and JT dispersion were significantly prolonged in patients with BS compared to those of the controls {37.5 ms [interquartile range (IQR) 32.5-40] vs. 25.5 ms (IQR 20-30), respectively, p = 0.014 and 37.5 ms (IQR 27.5-40) vs. 22.5 ms (IQR 20-30), respectively, p = 0.003}.

CONCLUSIONS: Elevated QT and JT dispersion during asymptomatic and normokalemic periods may be risk factors for the development of cardiac complications and arrhythmias in children with BS. In these patients the need for systematic cardiac screening and management protocol is extremely important for effective prevention.