Atrial Fibrillation and Peri-Atrial Inflammation Measured through Adipose Tissue Attenuation on Cardiac Computed Tomography

Abstract

Background: Inflammation plays a key role in atrial fibrillation (AF). Epicardial adipose tissue around the atrial wall can influence atrial morpho-functional properties. The aim of this study was to assess whether an increased quantity and/or density of adipose tissue located around the left atrium (Fat-LA) are related to AF, independently from atrial size. Methods: eighty patients who underwent AF ablation and 80 patients without history of AF were selected. The Fat-LA mass was quantified as tissue within −190 to −30 Hounsfield Units (HU) on cardiac computed tomography angiograms (CCTA), and the mean adipose tissue attenuation was assessed. Results: Adipose tissue mass was higher in patients with AF (5.42 ± 2.94 mL) versus non-AF (4.16 ± 2.55 mL, p = 0.007), but relative fat quantity did not differ after adjusting for atrial size. Mean fat density was significantly higher in AF (−69.15 HU) versus non-AF (−76.82 HU, p < 0.0001) participants. In the logistic regression models, only the addition of mean Fat-LA attenuation led to a significant improvement of the model’s chi-square (from 22.89 of the clinical model to 31.69 of the clinical and adipose tissue attenuation model, p < 0.01) and discrimination (AUC from 0.775 to 0.829). Conclusions: Fat-LA volume is significantly greater only in absolute terms in patients with AF, but this difference does not hold after adjusting for the larger LA of AF subjects. On the contrary, a higher Fat-LA density was associated with AF, independently from LA size, providing incremental value over other variables that are associated with AF.

Incremental value of the combined brain-cardiac CT protocol on prediction of atrial fibrillation after stroke

“…16 We found higher rates of EAT attenuation in patients developing AFDAS at follow-up compared to SR patients, and we described a cut-off of EAT attenuation > −85HU as independently associated with AFDAS in stroke patients, reflecting the inflammatory character of the EAT. This is corroborated by the study of Gaibazzi et al, 17 though with slightly different HU interval for EAT definition, ranging from −190 to −30HU.…”

“…Third, we measured the total volume of EAT and not only the atrial or even posterior wall atrial EAT, which seems to be play a more specific pathological role in AF. 8,17 Fourth, electrocardiographic markers of atrial cardiopathy such as P-wave duration or P wave terminal force in V1 were not collected and could not be implemented in our models. Thus, we were not able to assess atrial cardiopathy as defined in the ongoing ARCADIA trial, that will test a systematic anticoagulation of cryptogenic stroke patients with atrial cardiopathy markers.…”

“…For example, a cut-off of 40.68 cm 3 was found in Tsao et al 8 compared with 68.1 cm 3 /m 2 in Shmilovich et al 18 EAT attenuation appears to be more reproducible, which supported by our study in which EAT volume does not appear as a significant variable. 17 Others studies have also shown the impact of EAT localization, especially on the posterior wall of the LA, as a predictor of AF and cardiovascular events including stroke and tried to quantify it by different modalities (MRI, echocardiography, CCTA). 8,14,15,19…”

Impact of pericoronary adipose tissue attenuation on recurrence after radiofrequency catheter ablation for atrial fibrillation

“…The high level attenuation of adipose tissue in the posterior of LA may indicate the high‐level local inflammation and is independently associated with AF recurrence 8 . Adipose tissue attenuation is more reliably than fat volume because it does not depend on any anatomical markers established manually and subjectively by the researcher performing the measurement 9 . Unfortunately, we did not measure the attenuation of EAT surrounding the LA.…”

“…CCTA images were acquired with the following scan protocol: Tube voltage was 100 or 120 kV. If 100 kV voltage was used instead of 120 kV voltage, the mean Hounsfield units (HU) value was corrected dividing by 1.11485, as previously reported 9,10 . If the patient's heart rate was >65 beats/min, an oral or intravenous beta‐blocker was administered to reduce the heart rate before scanning.…”