QT dispersion predicts ventricular arrhythmia in pediatric cardiomyopathy patients referred for heart transplantation

Background: QT dispersion has been used in stratifying risk for sudden death in adults with dilated cardiomyopathy, but its role in the pediatric population has not been delineated. Methods: We reviewed electrocardiograms in pediatric patients with dilated cardiomyopathy referred for heart transplantation, to evaluate the role of QT dispersion in predicting malignant arrhythmias in these patients. Three groups were defined: Group I (n = 13) had dilated cardiomyopathy and malignant ventricular arrhythmias, Group II (n = 13) had dilated cardiomyopathy with no ventricular arrhythmias and Group III (n = 30) consisted of normals. QT dispersion was defined as the duration of the shortest QT subtracted from that of the longest. In addition, the standard deviation of the QT intervals was calculated for each EGG, using 12 leads. Results: QT dispersion was significantly prolonged in Group I (97 +/- 33 msec) compared to Group II (74 +/- 19 msec) and Group III (42 +/- 17 msec). QT standard deviation was also prolonged in Group I (30 +/- 11 msec) vs Group II (22 +/- 5 msec) and Group III (13 +/- 4 msec). Using a threshold value of 90 msec for QT dispersion or 25 msec for QT standard deviation, a sensitivity of 78% and a specificity of 70% was obtained for identifying patients who would subsequently develop ventricular arrhythmias. Conclusions: In pediatric heart transplant candidates with dilated cardiomyopathy, QT dispersion and QT standard deviation identify patients at higher risk for the development of malignant ventricular arrhythmia. This simple test can be helpful in the evaluation and management of these patients awaiting transplantation.