Proarrhythmic Effects Of Antiarrhythmic Drugs: Case Study Of Flecainide Induced Ventricular Arrhythmias During Treatment Of Atrial Fibrillation.

PURPOSE Flecainide is a class 1C antiarrhythmic drug especially used for the management of supraventricular arrhythmia. Flecainide also has a recognized proarrhythmic effect in patients treated for ventricular tachycardia. It is used to treat a variety of cardiac arrhythmias including paroxysmal atrial fibrillation, paroxysmal supraventricular tachycardia and ventricular tachycardia. Flecainide has local anesthetic effects and belongs to the class 1C AADs that block sodium channels, thereby slowing conduction through the heart. It selectively increases anterograde and retrograde accessory pathway refractoriness. The action of flecainide in the heart prolongs the PR interval and widens the QRS complex. The proarrhythmic effects however noted are not widely reported. METHOD We report a case of paroxysmal atrial fibrillation with structurally normal heart who was treated with oral Flecainide. There were no adverse events and no QTc prolongation was noted on ECG. Despite subjective improvement a repeat Holter detected him to have multiple short non sustained ventricular arrhythmias. RESULTS Development of ventricular arrhythmias, salvos and non-sustained ventricular tachycardia after a month of initiation of oral flecainide detected by 24 hours ECG Holter lead to discontinuation of flecainide and subsequent early electrophysiological studies and successful ablation. CONCLUSION Initiation of oral Flecainide in a case of atrial fibrillation with subjective improvement and regular ECG monitoring, no QTc prolongation can still lead to development of dangerous ventricular arrhythmias. A cautious approach and thorough investigations and follow up are recommended.