Clinical Correlates of Cardiac Conduction in Bipolar Disorder

Abstract

Introduction: To better understand the clinical correlates of electrocardiogram (ECG) QT interval prolongation and potential pathophysiological mechanisms of arrhythmias, sudden death and subsequent increased cardiovascular morbimortality in patients with bipolar disorder (BD), we investigated differences in cardiac conduction in subgroups of BD. Method(s): We included outpatients and inpatients age 18 through 80 with SCID/DSM5-confirmed BD from two hospitals in Santiago, Chile. We assessed cardiac conduction with a standard rest ECG focused on 1) PR, QRS and corrected QT (QTc) interval durations reported in milliseconds, 2) QRS and ST interval morphology. Patients were grouped by clinical features. Mann-Whitney and Kruskall-Wallis tests were used for comparisons. Result(s): A total of 117 patients were included (median age 34.5 [interquartile range (IQR) 21]), 61% women, 77.1% BD type I, 56.8% with >=1 hospitalization). Comorbid medical conditions encompassed obesity (28.8%), dyslipidemia (25.4%), hypertension (22%), diabetes (12.7%), smoking (39.8%). We found a significantly longer QTc interval among patients with hypertension (420 [IQR 48.5] vs 408 [IQR 44.5], p = 0.006) and obesity (425 [IQR 50] vs 404 [IQR 37.5], p = 0.001). We also observed a significantly shorter PR interval in women (152 [IQR 29] vs 158 [IQR 29.5], p = 0.018), age of onset <18 (148 [IQR 26] vs 158 [IQR 27], p = 0.013), history of adverse childhood experiences (155 [IQR 40] vs 160 [IQR 25], p = 0.038). There were no associations between current medication type and obesity, hypertension or QTc interval. Conclusion(s): These results may suggest different cardiac conduction phenotypes in BD which may have implications in spontaneous and/ or medication-induced arrhythmias, sudden death, and cardiovascular morbimortality.