Prevalence and relevance of H558R in the efficacy and toxicity of flecainide in patients with atrial fibrillation: a cohort study.

Background: The SCN5A gene polymorphism histidine-558-to-arginine (H558R) has been associated with atrial fibrillation (AF) and may affect the therapeutic effects of flecainide. This study aimed to assess the prevalence of the H558R polymorphism in a European cohort of patients with AF and examine its association with flecainide's effects on AF recurrence and toxicity.

Methods: This cohort study included patients diagnosed with AF and prescribed flecainide between 2017 and 2021 in a regional health area.