Distribution of Epicardial Adipose Tissue Surrounding the Left Atrium Predicts the Incidence of Atrial Fibrillation in Patients with Obstructive Sleep Apnea

Recent clinical studies have suggested that obstructive sleep apnea (OSA) is risk factor for atrial fibrillation (AF). However the underlying pathophysiological mechanism is unclear, because of the several factors as the autonomic effect contributing initiation of AF. Potential mechanism may be related to epicardial adipose tissue (EAT) containing the ganlionic cluster, influence of the intrinsic autonomic nerve system. The aim of this study was to determine whether the amount of EAT is associated to AF in severe OSA pts. 9 pts (8 male, 56±8 years, BMI 26.1±1.9) with severe OSA (apnea hypopnea index: AHI 41.6±6.9) were measured by multi-slice computed tomography. Total volume of EAT (EAT-total) and EAT volume around the LA (EAT-LA) were identified by threshold setting of −200 to −30 Hounsfield units. The distribution of EAT was discribed as EAT-LA/EAT-total index (EATI: %), compared between 4 pts with evidence of AF (AF-OSA) and 5 pts without AF (Control-OSA). Age, BMI, and AHI had no significant difference in both groups. AF-OSA had a significantly higher EATI than Control-OSA (3.3±0.8 vs 1.3±0.3%, p<0.01), and EAT-total, EAT-LA were slightly increased (84.8±45.2 vs 78.9±27.4 cm3, p=0.12, 3.2±1.6 vs 1.3±0.3 cm3, p=0.11) in AF-OSA. In conclusion, EAT distribution has substantial contribution to the incidence of AF in patients with OSA.