Differences in Pulmonary Vein Perivascular Fat may be a Unique Marker of Adipose Tissue Activity in AF Patients Undergoing AF Ablation

Abstract

Epicardial adipose tissue (EAT) secretes pro-inflammatory molecules potentially promoting atrial remodelling and atrial fibrillation (AF), however it may not determine loco-regional effects. Perivascular fat is identified as a potential sensor of adjacent vessel inflammation. Peripulmonary vein (PV) fat measurement may demonstrate a simple non-invasive marker of PV fat activity. We retrospectively identified patients undergoing cardiac CT pre-AF ablation and a cohort of non-AF patients with suspected CAD. EAT and PV adipose tissue volume (mL) and mean density (Hounsfield Units [HU]) were measured using validated software (QFAT, Cedars-Sinai, USA). 106 patients were included (47.2% AF, 52.8% non-AF). Mean age (66 yrs) and BMI were similar. T2DM and IHD were more common in non-AF patients, 76% vs 23%. AF patients exhibited larger EAT volume and lower mean density (95±53mL vs 66±30mL, p=0.002; density -86±5HU vs -75±7HU, p<0.0001). AF patients had significantly higher volume of fat in left upper and lower PVs (LUPV volume 26±19mL vs 8±8mL, p<0.0001, LLPV volume 25±22mL vs 13±14mL, p=0.003). AF patients had lower LUPV and LLPV density (LUPV -66±9HU vs -57±14HU, p=0.0001; LLPV -69HU vs -62HU, p=0.01). There was no significant difference in right sided PV volume or density. Compared with suspected CAD controls, AF patients had higher left-sided PV fat volumes and lower mean density. This may represent regional specific changes in tissue characteristics relating to PV automaticity. Further histopathologic, electrophysiologic and serum biomarker comparative analysis is necessary to confirm these findings and their effect on AF ablation outcomes.