Shaped by age: The right atrium in atrial septal defect

Background Atrial septal defect (ASD) is associated with an increased risk of atrial fibrillation, traditionally attributed to chronic right atrial (RA) volume overload. However, the contribution of aging, independent of volume overload, to RA remodeling is unclear. Objective To determine the role of aging in RA electrical remodeling in unrepaired ASD patients without atrial tachyarrhythmias. Methods High-resolution epicardial RA mapping was performed in 72 ASD patients (34 pediatric, 38 adult) before surgical correction. Potential morphology, low-voltage areas (LVA), and conduction block (CB) were quantified. Associations between age and electrophysiological properties were assessed using linear regression models adjusted for clinical covariates. To isolate the effect of age, an additional generalized estimating equation analysis was conducted in an age-matched cohort of 45 non-ASD controls. Results In ASD patients, age was independently associated with higher LVA burden (β[95% CI] per 10 years: 1.4% [0.7–2.0]; P <0.001), long-double potentials (LDP; 0.9%, [0.2–1.5]; P =0.008), and CB (0.5% [0.2–0.8]; P =0.001) in fully adjusted model. These age-related associations were region-specific, mainly involving LVA in superior RA, LDP in inferior RA, and CB in RA free wall. Age-related associations persisted in control cohort, supporting an effect independent of ASD-related volume overload (fully adjusted model: LVA: 1.3% [0.5–2.1]; LDP: 1.3% [0.5–2.0]; CB: 0.7% [0.4–0.9]; P <0.001, respectively). Conclusions Aging is an independent contributor to RA electrical remodeling in unrepaired ASD patients. These findings highlight the role of age as a substrate modifier, independent from volume overload, may guide arrhythmia risk stratification in this population.