Left atrial remodeling and functional maladaptations in obesity: an invasive pressure-volume analysis
TL;DR
In patients undergoing AF ablation, higher BMI is associated with a predominantly load-related pattern of LA remodeling, characterized by larger LA volume and pressures, greater cyclic wall stress, and a rightward shift of the estimated pressure–volume relationship.
Abstract
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 in patients with AF referred for catheter ablation. Methods We studied 1,040 consecutive patients (67% men, mean age 62 years, 71% in sinus rhythm). Participants were stratified by BMI (<25.0, 25.0–29.9, 30.0–34.9, and ≥35.0 kg/m2). 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 had larger estimated total blood and plasma volumes along with higher LA volumes and pressures, greater cyclic wall stress, and a rightward shift of the estimated LA pressure–volume relationship. Conversely, estimated operant LA stiffness did not differ across BMI strata. BMI-related differences in LA volume were attenuated by body surface area indexing but preserved with height-based indexing. Conventional volumetric indices of LA phasic function were similar across BMI strata, whereas available LA strain indices (n=107) were lower in greater adiposity, consistent with worse LA phasic function. 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 a predominantly load-related pattern of LA remodeling, characterized by larger LA volume and pressures, greater cyclic wall stress, and a rightward shift of the estimated pressure–volume relationship. BMI-associated early atrial remodeling may precede overt atrial dysfunction, potentially contributing to the link between excess adiposity, AF, and HFpEF.