Left atrial remodeling and functional maladaptations in obesity: an invasive pressure-volume analysis

Background Obesity is a major risk factor for atrial fibrillation (AF) and heart failure (HF). We aimed to characterize left atrial (LA) structural and functional changes across body mass index (BMI) strata by integrating morpho-volumetric, functional, and pressure-derived measures. Methods We studied 1,040 consecutive patients referred for catheter ablation of AF (67% males, mean age 62 years, 71% in sinus rhythm). Participants were stratified by BMI. Comprehensive echocardiographic assessment of LA structure and function was integrated with invasive LA pressure measurements obtained via transseptal access during the ablation procedure. Associations across BMI strata were evaluated using regression analyses. Results Patients with higher BMI showed larger estimated total blood and plasma volumes along with stepwise increases in LA volume, pressure, and cyclic wall stress, and a rightward shift of the LA pressure–volume relationship. Conversely, operant LA stiffness did not differ across BMI strata (Figure). BMI-related differences in LA volume were attenuated by body surface area indexing but preserved with height-based indexing (Figure). Conventional volumetric indices of LA phasic function showed only weak associations with BMI, whereas LA strain and the LA function index worsened progressively with increasing BMI. Compared with patients without HF, those with HF exhibited more pronounced structural, functional, and hemodynamic atrial remodeling, consistent with a more advanced atrial myopathy phenotype. Conclusions In patients undergoing AF ablation, higher BMI is associated with an early, load-related pattern of LA remodeling characterized by progressive atrial enlargement, increased pressures and cyclic wall stress, and a rightward shift of the pressure–volume relationship. Atrial volume overload represents a viable treatment target in obesity-related LA remodeling.