Ventricular fibrillation associated with Graves' disease and amiodarone induced thyrotoxicosis.

This case involves a 55-year-old male patient with systolic heart failure and refractory atrial fibrillation due to thyrotoxicosis, who was electrically cardioverted but then developed torsade de pointes and ventricular fibrillation. Rate control was unsuccessful with digoxin, cardizem, labetalol, esmolol and amiodorone. Patient was externally cardioverted after which ECGs showed prolonged QT with frequent premature ventricular contractions. ECGs also showed 'R-on-T' phenomenon leading to torsades and ventricular fibrillation. Atrial overdrive pacing was used to terminate the dangerous arrhythmia and the patient returned to sinus rhythm. Interestingly, he was found to have new onset thyrotoxicosis and started on methimazole.