QT AND JT DISPERSION IN CHILDREN WITH LONG-QT-SYNDROME

Introduction: Abnormalities of ventricular repolarization leading to v entricular arrhythmias place children with long QT syndrome at high ri sk for sudden death, Dispersion of the QT (QTd) and JT (JTd) intervals , as markers of cardiac electrical heterogeneity, may be helpful in ev aluating children with long QT syndrome and identifying a subset of pa tients at high risk for development of critical ventricular arrhythmia s (ventricular tachycardia, torsades de pointes, and/or cardiac arrest ), Methods and Results: The QTd and JTd intervals in 39 children with long QT syndrome were compared to those of 50 normal age-matched child ren, In the long QT syndrome group, QTd measured 81 +/- 70 msec compar ed to 28 +/- 14 msec in the control group (P < 0.05), and JTd in the l ong QT syndrome group was 80 +/- 69 msec compared to 25 +/- 15 msec in the control group (P < 0.05). Conclusion: Children with long QT syndr ome have an increased QTd and JTd when compared to normal controls, A QTd or JTd greater than or equal to 55 msec correlates with the presen ce of critical ventricular arrhythmias. These ECG measures of dispersi on can be useful in stratifying children with the long QT syndrome who are at higher risk for developing critical ventricular arrhythmias.