Ventricular tachycardia unveiling severe undiagnosed hypothyroidism

Hypothyroidism is typically associated with bradyarrhythmias, but can rarely precipitate life-threatening ventricular arrhythmias. We present a case of severe hypothyroidism manifesting as polymorphic ventricular tachycardia (VT). A previously healthy woman in her early 50s presented with an acute onset of breathlessness and on examination had hypotension and tachycardia. ECG revealed polymorphic VT, promptly terminated by defibrillation using 200J biphasic shock. Investigations uncovered severe primary hypothyroidism (thyroid-stimulating hormone: 142 mIU/l) and left ventricular (LV) dysfunction with ejection fraction (EF) of 35%. Coronary angiogram was normal. Treatment with levothyroxine and standard heart failure therapy was initiated. In conclusion, at 3- and 6-month follow-ups, the patient remained asymptomatic and had no episodes of tachyarrhythmias without antiarrhythmic drugs, and her LV function normalized (EF: 55%). This case highlights the importance of considering hypothyroidism in patients presenting with unexplained ventricular arrhythmias.