Early-onset atrial fibrillation without structural heart disease: lifestyle and hereditary risk factors

Atrial fibrillation (AF) before the age of 40 is rare,1 particularly in the absence of structural heart disease (SHD), and remains insufficiently described. While AF in older adults is driven by age-related remodeling and cardiovascular risk factors,2,3 the determinants of young-onset AF are less defined. Although AF has been associated with cardiomyopathies—often with a strong genetic component4—many young patients develop AF despite an apparently normal heart and without acute medical triggers, raising questions about the origins of the arrhythmia. We hypothesized that lifestyle factors, familial predisposition, and genetic variants5 may contribute. Prognostic data in this population are scarce. Most available studies are retrospective, merge all AF cases below a certain age without distinguishing SHD status, and provide limited phenotypic detail. Thus, the prognosis of these patients remains poorly understood, particularly regarding whether AF may represent the first manifestation of an otherwise concealed cardiomyopathy. We therefore sought to prospectively characterize demographic, clinical, and genetic features of patients with AF before age 40 without SHD, and to describe their rhythm management and mid-term outcomes.