Brief Summary:

Current guidelines for the cardioversion of paroxysmal Atrial Fibrillation at the Emergency Department do not prioritize between antiarrhythmic agents and do not consider the time taken for successful cardioversion. Furthermore, the use of flecainide -a class 1C antiarrhythmic agent- is contraindicated for the cardioversion of patients with revascularized coronary artery disease, as well as patients with ischemic cardiomyopathy and preserved ejection fraction. These recommendations stem from insufficient data, mainly from the CAST study. The present study is a prospective, multicentre, randomized clinical trial. The primary goals of this clinical trial are to prove the superiority of flecainide over amiodarone in the successful cardioversion of paroxysmal atrial fibrillation at the Emergency Department, and to prove that the safety of flecainide is non-inferior to amiodarone, in patients with coronary artery disease without residual ischemia and ejection fraction over 35%. The secondary goals of the study are to prove the superiority of flecainide over amiodarone in the reduction of hospitalizations from the Emergency Department due to atrial fibrillation, in the time taken to achieve cardioversion, and to the reduction of the need to conduct electrical cardioversion. The study population will be all consecutive new-comers to the Emergency Department with primary diagnosis of paroxysmal atrial fibrillation and history of coronary artery disease without angina, without residual ischemia and with ejection fraction > 35%. The sample size will be 200 patients, who will be monitored for 30 days. At the Emergency Department, all patients will be under continuous ECG monitoring, and a 24-hour ECG device will also be placed (Holter). The patients will be randomized to the treatment group (flecainide) and the control group (amiodarone). Patients in both arms will stay at the ED for a total of 6 hours after therapy initiation. If no adverse events occur in this time, the patient will be discharged from the ED. Otherwise, the patient will be admitted to the hospital. At 24 hours, the patients will visit the study centre for physical examination, ECG, cardiac ultrasound, 24-hour ECG removal and adverse events evaluation. At 30 days, follow-up via phone calls will be conducted for the evaluation of the study outcomes and adverse events.