A Pediatric Case of Refractory Torsades de Pointes in Autoimmune Hypothyroidism

Abstract

Hypothyroidism can have a significant impact on cardiac contractility, vascular resistance, blood pressure, and cardiac rhythm. Ventricular arrhythmias induced by hypothyroidism are infrequently reported, especially in pediatric cases. A 15-year-old girl with autoimmune hypothyroidism experienced pulseless ventricular arrhythmias on 2 separate occasions because of nonadherence to levothyroxine medication. Subsequent investigations revealed an SCN5A mutation associated with Brugada syndrome. A loop recorder captured polymorphic ventricular tachycardia (PMVT), specifically Torsades de Pointes during her second event. Both arrhythmias were addressed only after stabilizing her thyroid hormone levels with replacement therapy. Although rare, patients with uncontrolled hypothyroidism may present with ventricular arrhythmias, particularly PMVT. The cornerstone of treatment for hypothyroidism-induced ventricular arrhythmia is thyroid replacement therapy. The identification of an SCN5A mutation unmasked by overt hypothyroidism emphasizes the need for a comprehensive cardiac evaluation in patients with hypothyroidism being assessed for PMVT.

Keywords: Brugada syndrome; Torsades de Pointes; hypothyroidism; polymorphic ventricular tachycardia; ventricular arrhythmia.

Figure 1.

Loop recorder tracings at the time of syncope and cardiac arrest. (A) Inciting rhythm shows ventricular bigeminy. (B) Demonstration of bigeminy propagating ventricular tachycardia. (C) Polymorphic ventricular tachycardia, in this case, Torsades de Pointes. (D) Ventricular tachycardia degenerating into ventricular fibrillation.