Severe hypothyroidism presenting with supraventricular tachycardia.

Thyroid disease is common and can have various systemic manifestations including cardiac diseases. Hypothyroidism is commonly associated with sinus bradycardia, low QRS complexes, prolonged QT interval and conduction blocks but rarely may cause arrhythmias. We present a patient who presented with presyncope and supraventricular tachycardia with severe hypothyroidism. Patient responded well to thyroxine replacement with biochemical improvement, the disappearance of arrhythmia after restoration of euthyroidism suggests that hypothyroidism might be the cause of supraventricular tachycardia. The aim of this report is to underline the possible aetiological link between supraventricular tachycardia and hypothyroidism, although supraventricular arrhythmias are ordinary features of hyperthyroidism.