Abstract P1022: Interatrial Septal Thickening as a Predictor of Atrial Fibrillation and Structural Heart Remodeling

Abstract

Introduction: Lipomatous hypertrophy of the interatrial septum is characterized by adipose deposition in the interatrial septum (IAS). Although generally considered benign, its associations with arrhythmias and remodeling are not well understood and require further investigation. Understanding the role of IAS thickening in arrhythmogenesis and remodeling could improve detection and management. Hypothesis: We hypothesized that increased IAS thickness is associated with a higher prevalence of atrial fibrillation (AF), larger body surface area (BSA), interventricular septal thickness (IVS), coronary artery disease (CAD), and valvular disease. Methods: We conducted a retrospective analysis of 208 consecutive patients who underwent transesophageal echocardiography. IAS thickness was manually measured in the bicaval view by a trained physician at our academic center. IAS thickness was stratified into the groups <6 mm, 6-12 mm, and >12 mm. We analyzed variables including IVS thickness, valvular defects, electrocardiogram abnormalities, medications, and morbidities such as diabetes and hypertension. BMI and BSA were calculated. Chi-square and ANOVA were used to assess statistical significance (p < 0.05). Results: Among the 208 patients (mean age 60.5 years; 56% male), IAS thickening was significantly associated with increased BSA (p < 0.05), suggesting that body size and metabolic factors contribute to septal hypertrophy and structural heart changes. Patients with thicker IAS also had increased IVS thickness (p < 0.05), indicating that hypertrophic changes extend beyond the atrial septum to affect broader myocardial structures. IAS thickening was linked to CAD (p < 0.05) and mitral regurgitation (p < 0.05), suggesting that septal hypertrophy may serve as a marker for valvular pathology and atherosclerotic burden. AF was strongly correlated with increased IAS thickness (p < 0.05), reinforcing its link to electrical and structural heart remodeling. Conclusions: Increased IAS thickness may be associated with atrial arrhythmias, BSA, IVS thickness, CAD, and valvular dysfunction. Particularly in patients with cardiovascular risk factors, IAS thickening is linked to arrhythmias and structural heart changes. It may serve as a valuable marker for identifying at-risk patients and enabling earlier intervention to prevent adverse cardiac events. Larger studies are necessary to further explore these associations and deepen our understanding of IAS thickening’s clinical significance.