Low incidence of atrial fibrillation in patients with obstructive hypertrophic cardiomyopathy treated with aficamten: An analysis from the REDWOOD-HCM, SEQUOIA-HCM, and FOREST-HCM trials

Atrial fibrillation (AF) occurs in 20%–25% of patients with obstructive hypertrophic cardiomyopathy (oHCM) (incidence ∼2%–5%/y) and is associated with significant morbidity. 1 Cardiac myosin inhibitors (CMIs) relieve outflow obstruction and improve symptoms, although data from open-label extension (OLE) studies with extended drug exposure and real-world data raise concerns over higher-than-anticipated rates of new-onset AF, potentially increasing the risk of systolic dysfunction and acute heart failure (HF). 2–4 Aficamten is a next-in-class CMI demonstrated to be safe and effective in improving obstruction and health status. AFrelated adverse events (AEs) were uncommon in a randomized 24-week trial. 5 Given this relatively short exposure, we sought to determine whether extended treatment results in higher rates of new-onset AF and whether treatment benefit and rates of other cardiac AEs differ in patients with AF.