EFFECTS OF ANTIDEPRESSANTS ON DECELERATION CAPACITY AND ITS RELATION TO QT INTERVAL IN PATIENTS WITH MOOD DISORDER

Abstract Background and Objectives Patients with mood disorders on antidepressants have a high rate of sudden cardiac death (1). Some antidepressants have been implicated as risk factors for QT prolongation, which is a predictor of sudden cardiac death (2). However, the QT interval is considered an imperfect biomarker for proarrhythmic risk. Decreased instantaneous cardiac deceleration capacity (DC) is associated with increased risk of post-myocardial infarction death and is thought to represent cardiac reserve (3). To evaluate the risk of sudden cardiac death associated with antidepressants, we examined the association between DC and patients with mood disorders using antidepressants and other medications. Method DC was measured using a heart rate sensor (my Beat wearable heart rate sensor/WHS-1: Union Tool Corporation) in 102 patients (45 males, age 53.8±16.2) with mood disorders who gave written consent at Dokkyo Medical University Hospital and Fudogaoka Hospital. We compared the DC of 68 age- and sex-matched healthy controls with that of 68 mood disorder patients. And we investigated the correlation of DC of 102 mood disorder patients with prescribed doses of antipsychotics using multiple regression analysis. Furthermore, we compared the DC of mood disorder patients with and without prolonged QT intervals. This study was approved by the Bioethics Committee of Dokkyo Medical University. There are no conflicts of interest to disclose. Results We found DC significantly differed between patients with mood disorder on antidepressants and other psychotropic medications and healthy controls (mean value of DC: 5.7 ms for the patient group and 7.3 ms for the healthy group). Multiple regression analysis showed that age (β = -0.070) and antidepressant use (imipramine equivalent: per 150 mg) (β = -0.92) were associated with decreased DC. In models examining individual antidepressants, age (β= -0.061) and clomipramine (per 120 mg) (β= -5.5) and amitriptyline (per 150 mg) (β= -6.9) were associated with decreased DC. On the other hand, there was no significant difference in DC in patients with mood disorder taking antipsychotics with and without QT prolongation. Discussion and Conclusion Assessing DC could facilitate monitoring and identification of increased risk of cardiac mortality in patients with mood disorder that take antidepressants. DC and QTc are considered to be independent measures, and assessing both DC and QTc may enhance the accuracy of predicting sudden cardiac death with antidepressants. References (1)Sicouri S, Antzelevitch C. Sudden cardiac death secondary to antide pressant and antipsychotic drugs. Expert Opin Drug Saf 2008;7:181-194. (2)Reilly JG, Ayis SA, Ferrier IN, Jones SJ, Thomas SH. QTc-interval ab normalities and psychotropic drug therapy in psychiatric patients. Lancet 2000;355:1048-1052. (3)Bauer A, Kantelhardt JW, Barthel P, Schneider R, Mä kikallio T, Ulm K, et al. Deceleration capacity of heart rate as a predictor of mortality after myocardial infarction: cohort study. Lancet. 2006;367(9523):1674-81.