QT dispersion in the surface electrocardiogram in elderly patients with major depression

Background: QT dispersion (QTd) is a measure of interlead variations of QT interval of the surface 12-lead electrocardiogram (ECG). Increased QTd, found in various cardiac diseases, reflects cardiac instability and is associated with increased cardiac death. Major depressive disorder (MDD) was found to be associated with high cardiovascular mortality rates. This study compares QTd in elderly patients with MDD to normal controls. Methods: QTd and rate-corrected QTd of 18 physically healthy elderly patients (69.9±7.6 years) with MDD was compared to nine physically and mentally healthy age- and gender-matched controls (64.1±12.2 years). Results: QTd and rate-corrected QTd were significantly higher in MDD compared to controls (68±30 vs. 40±13 ms, P=0.002 and 81±39 vs. 43±13 ms, P=0.001, respectively). Intra- and inter- observer reproducibilities were highly correlated (r=0.96, P <0.0001; r=0.88, P <0.001, respectively). Limitations and Conclusions: The major limitations of this study are the small number of subjects and the fact that all the patients were maintained on antidepressant medication. However, it seems that QTd analysis might shed light on possible autonomic imbalance and also provide a novel cardiovascular risk factor for increased cardiac death in MDD.