Ventricular arrhythmias after electrical cardioversion for AF are rare. Most of these arrhythmias are related to QT prolongation, resulting from marked and sudden slowing of heart rates, treatment with Class III antiarrhythmic drugs or other QT-prolonging medications, and the ventricular repolarisation remodelling effect of electrical cardioversion. A case of polymorphic ventricular tachycardia post-cardioversion of rapid AF in a patient with tachycardia-induced cardiomyopathy and the use of amiodarone is reported.