Left atrial epicardial adipose tissue radiodensity is associated with electrophysiological properties of atrial myocardium in patients with atrial fibrillation.

Objective: To evaluate whether the epicardial adipose tissue (EAT) phenotype is associated with the electrophysiological properties of adjacent atrial myocardium in patients with atrial fibrillation (AF).

Methods: Between January and May 2017, 30 consecutive patients referred for a first AF catheter ablation were prospectively included. For each patient, a pre-procedural computed tomography scan was performed to assess total and left atrial (LA) EAT amount and radiodensity. A detailed point-by-point voltage mapping using an electroanatomic mapping system was realized to assess the presence of LA low-voltage zone (LVZ).

Results: Ten patients (33.3%) presented at least one LVZ. Older age (65 ± 7 vs. 58 ± 10 years, p = 0.05) was the only clinical parameter associated with LVZ. Despite no greater LA-EAT thickness by CT scan (3.0 [2.6-3.5] mm vs. 2.8 [2.2-3.1] mm, p = 0.354), patients with LA-LVZ presented significantly lower LA-EAT radiodensity than patients with no LA-LVZ (- 101.8 ± 12.5 HU vs. - 90.4 ± 6.3 HU, p = 0.004). No difference between total-EAT volume (131 ± 61 cm vs.107 ± 58 cm, p = 0.361) and total-EAT radiodensity (- 106.8 ± 4.3 HU vs. - 102.4 ± 6.9 HU, p = 0.119) was found.

Conclusion: Low LA-EAT radiodensity is associated with the presence of LVZ in patients with medical history of AF.

Key Points: • Cardiovascular risk factors are associated with low adipose tissue computed tomography attenuation. • Epicardial adipose tissue (EAT) has emerged as an important factor in the pathogenesis of metabolic-related cardiac diseases such as atrial fibrillation. • We showed that low left atrial EAT attenuation is associated with the presence of low-voltage zone, a surrogate for atrial fibrosis, within the adjacent myocardium.