Drug-free patients with major depressive disorder (MDD) are understudied in terms of increased risk for arrhythmias. In this study, we compared changes in corrected QT interval (QTc), QTc dispersion (QTcd), Tpeak-Tend (Tp-e), Tp-e/QT ratio, corrected JT interval (JTc), and JTc dispersion (JTcd), which are considered to be among the risk factors for the emergence of ventricular arrhythmias in patients with MDD.

The study involved 50 patients with MDD who had been free of psychotropic medications for at least 1 month and 52 age-matched and sex-matched healthy controls. Illness-related characteristics, including duration of illness and Beck Depression Inventory scores, were recorded. Electrocardiography recordings made under a standardized procedure were performed for all participants, and arrhythmia risk markers were calculated from the electrocardiograms.

The patient group had significantly higher QTcd, JTc, and JTcd values compared with the controls. Among electrocardiogram markers, only Tp-e/QTc was significantly and inversely correlated with the duration of illness, while none of the markers was associated with Beck Depression Inventory scores.

Alterations in electrocardiogram-derived markers of ventricular arrhythmia, which can be obtained easily and inexpensively, can be evaluated for the prediction and prevention of severe cardiac conditions in patients with MDD and considered in selecting the safest antidepressant options available.