Thyrotoxicosis-induced ventricular arrhythmias

Cardiac arrhythmias associated with thyrotoxicosis tend to be supraventricular in nature with atrial fibrillation being the most common. Ventricular arrhythmias are rarely associated with thyrotoxicosis and are considered to be secondary to intrinsic cardiac disease.

We present three patients with thyrotoxicosis and stable coronary disease in whom the primary cardiac rhythm disturbance was ventricular tachycardia. In all of these patients, the ventricular arrhythmias terminated with achievement of a euthyroid state. We hypothesize that the thyrotoxic state contributed to the etiology of, or lowered the threshold for the ventricular arrhythmias.

Prompt attention to the management of thyrotoxicosis in patients with a history of significant heart disease is warranted in order to avoid potentially fatal arrhythmias.