QT Dispersion in Nonischemic Dilated Cardiomyopathy. A Long-Term Evaluation

BACKGROUND: In idiopathic dilated cardiomyopathy (IDC), the predictive value of QT dispersion is still under debate. AIMS: This study assessed the role of QT dispersion for the long-term risk of cardiac death and of major arrhythmic events in IDC. METHODS AND RESULTS: In 162 patients with IDC (age 52+/-12 years), the QT interval on a 12-lead ECG was measured manually. QT dispersion was evaluated with QT range and QT standard deviation, for both QT and QTc (Bazett formula). With a follow-up of 53+/-41 months, QT dispersion was not a predictor of cardiac death in univariate or in multivariate analysis, and was of similar value for patients with or without bundle branch block. Using multivariate analysis, increased pulmonary capillary wedge pressure (p=0.003), decreased heart rate variability (Standard deviation of all NN intervals, p=0.01) and non-sustained ventricular tachycardia (NSVT) (p=0.03) were predictors of cardiac death. Sudden death and/or major arrhythmic events were independently predicted by NSVT (p=0.005), decreased heart rate variability (p=0.01) and late ventricular potentials on signal averaged ECG (p=0.02). CONCLUSION: This study confirms the poor prognostic value of QT dispersion in patients with IDC. Other methods to assess repolarization abnormalities need to be evaluated in such patients.