Transient bradyarrhythmia: A sole presentation of amiodarone-induced hypothyroidism

Abstract

Amiodarone is a class III anti-arrhythmic drug which is commonly used in various cardiac arrhythmias. Hypothyroidism is one important complication linked with this drug. Herein, we recount a case of amiodarone-induced hypothyroidism, which presented as atrial fibrillation (AF) with slow ventricular response. A middle-aged gentleman was brought to the casualty in unconscious state. He was a known case of hypertension and on amiodarone treatment for AF for the past 2 years. On presentation, the patient had a slow pulse rate and his electrocardiogram was suggestive of AF with very slow ventricular beat. This was managed medically and a temporary cardiac pacemaker was instituted thereafter. In search of the cause for bradycardia, his thyroid function test depicted hypothyroidism with 2-fold raised thyroid-stimulating hormone and decreased levels of free tetraiodothyronine hormone, but the patient had no other features suggestive of hypothyroidism. Therefore, the patient was started on oral thyroxine hormone, which led to considerable pulse rate improvement.