Safety and efficacy of the use of intravenous flecainide in the context of an aggressive rhythm control strategy in patients with atrial fibrillation in the emergency department (HEROMEDICUS study)

Introduction

Atrial fibrillation (AF) accounts for 1% of emergency department (ED) visits at a general hospital. The lack of specific guidelines for the treatment of AF in the acute phase justifies the use of a conservative versus a more aggressive strategy.

Purpose

In the HEROMEDICUS study we developed a protocol for the treatment of these patients in the acute phase. The protocol includes an aggressive electrophysiologist-guided rhythm control strategy for patients presenting with AF in the ED. In the present study, the endpoint is the safety and efficacy of AF reduction with intravenous flecainide in the ED.

Methodology: All patients who visited the ED from September 2023 to October 2025 were tested for possible inclusion in the protocol. Those with a known history of heart failure, coronary heart disease or symptoms of acute heart failure or evidence of acute coronary syndrome were excluded. With the use of tablet and an application designed specifically for this protocol, there was continuous counseling by a specialist electrophysiologist. Patients without prior home loading with >300 mg propafenone or >200 mg flecainide were given iv flecainide (2 mg/kg, up to 150 mg dose in 10'). After patients’ discharge from ED, monitoring was scheduled through the application at the outpatient AF clinic.

Results

From the period of 08/09/2023 to 10/10/2025, 277 cases with AF inclusion study criteria were presented to the ED of our hospital, of which 15 had atrial tachycardia, 28 had atrial flutter and 234 had AF. Mean age was 71.3±5.7 years (53% female) and 130 patients had their first AF episode. Mean CHa2ds2-VASc score was 2.2± 0.15, mean ventricular frequency was 120 ±3.5 and 43% were on prior anticoagulation medication. Among 85 patients receiving intravenous flecainide, 61 (71.7%) were successfully converted to sinus rhythm. From the remaining 24 patients, 22 were then electrically cardioverted to sinus rhythm in the ED and only 2 patients failed both iv flecainide and electrical cardioversion. No patients experienced ventricular proarrhythmia or atrial flutter with 1 to 1 treatment. Adimission took place in only 4.6% of the total study population.

Conclusion

Flecainide intravenously can be safely and effectively udes in the ED for the cardioversion of AF resulting in significant reduction of admissions.