Rosh Psychiatry Board Practice Exam

Which complication is most closely associated with an overdose of cyclic antidepressants?

1. Dilated cardiomyopathy

2. Ebstein anomaly

3. Myocarditis

4. Torsades de pointes

The correct answer is: Torsades de pointes

An overdose of cyclic antidepressants, particularly tricyclic antidepressants (TCAs), can lead to a number of serious complications, with one of the most critical being torsades de pointes. This is a life-threatening form of polymorphic ventricular tachycardia that can occur due to prolonged QT interval, which is a known effect of TCAs. They can cause significant cardiac conduction abnormalities, leading to arrhythmias, including torsades de pointes, by inhibiting sodium channels and affecting the repolarization phase of cardiac action potentials. The risk of developing torsades de pointes increases particularly when there are additional factors such as electrolyte imbalances (like hypokalemia or hypomagnesemia) or the presence of other medications that also prolong the QT interval. Given this mechanism of action and the potential for serious cardiac complications during TCA overdose, torsades de pointes is the most closely associated complication with this scenario. Other complications, while they may arise from various cardiac conditions, do not have a direct and immediate association with TCA overdose as torsades de pointes does. Thus, understanding the pharmacological effects of cyclic antidepressants on cardiac function is crucial in recognizing the risk of torsades de pointes during overdose situations.