Flecainide to Prevent Atrial Arrhythmia After Patent Foramen Ovale Closure: AFLOAT Study, A Randomized Clinical Trial.

Background: The real incidence of atrial arrhythmia (AA) after patent foramen ovale (PFO) closure and whether this complication can be prevented remain unknown. We assessed whether flecainide is effective to prevent AA during the first 3 months after PFO closure, and whether 6 months of treatment with flecainide is more effective than 3 months to prevent AA after PFO closure.

Methods: AFLOAT (Assessment of Flecainide to Lower the Patent Foramen Ovale Closure Risk of Atrial Fibrillation or Tachycardia Trial) is a prospective, multicentre, randomized, open-label, superiority trial with a blind evaluation of all the end points (PROBE [Prospective Randomized Open, Blinded End Point] design). Patients were randomized in a 1:1:1 ratio after PFO closure to receive flecainide (150 mg once daily in a sustained-release dose) for 3 months, flecainide (150 mg once daily in a sustained-release dose) for 6 months, or no additional treatment (standard of care) for 6 months. The primary end point was the percentage of patients with at least 1 episode of AA (≥30 seconds) recorded within 3 months after PFO closure on long-term monitoring with an insertable cardiac monitor. The secondary end point was the percentage of patients with at least 1 episode of AA (≥30 seconds) recorded with insertable cardiac monitor during the 3- to 6-month period after PFO closure.

Results: A total of 186 patients were included (mean age, 54 years; 68.8% men) and AA (≥30 seconds) occurred in 53 patients (28.5%) during the 6-month follow-up; 86.8% of these AA events occurred in the first month after PFO closure. The primary outcome occurred in 33 of 123 (26.8%) and 16 of 63 (25.4%) patients receiving flecainide for at least 3 months or standard of care, respectively (risk difference, 1.4% [95% CI, -12.9% to 13.8%]; NS). The secondary end point occurred in 3 of 60 (5.0%), 4 of 63 (6.3%), and 5 of 63 (7.9%) patients receiving flecainide for 6 months, for 3 months, or standard of care, respectively (risk difference, -2.9% [95% CI, -12.7% to 6.9%], and risk difference, -1.6% [95% CI, -11.8% to 8.6%], respectively).

Conclusions: In the first 6 months after successful PFO closure, AA (≥30 seconds) occurred in 28.5% of cases, mostly in the first month after the procedure. Flecainide did not prevent AA after PFO closure.

Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05213104.