Epicardial atrial fat: not quite as idle as it looks

Left atrial epicardial adipose tissue is associated with low voltage zones in the left atrium in patients with non-valvular atrial fibrillation

Objective

Epicardial adipose tissue (EAT) is related to atrial fibrillation (AF), but the specific mechanism is still unclear. Left atrial (LA) low voltage zones (LVZ) can well reflect atrial fibrosis. This study investigated the relationship between EAT and LVZ in non-valvular AF (NVAF) patients.

Methods

This observational study including patients with NVAF (n = 214) undergoing radiofrequency ablation (RFCA) for the first time in our hospital and 62 matched controls. The EAT volume and attenuation were measured by contrast-enhanced computed tomography. A three-dimensional mapping system was used to map the left atrial endocardium and evaluate LA-LVZ. Patients were divided into LVZ and non-LVZ groups according to the presence or absence of LVZ.

Results

Patients with AF showed higher LA-EAT volume and lower attenuation value than controls (29.7 ± 11.2 cm³ vs. 20.9 ± 8.6 cm³, P = 0.021; −91.2 ± 5.6 HU vs. −88.7 ± 5.9 HU, P < 0.001). Compared with the group without LVZ, there were significant differences in age [65 (59–71) vs. 60 (52–69), P = 0.006], LAVI [75.1 ± 20.7 ml/m² vs. 67.2 ± 20.9 ml/m², P = 0.018], LA-EAT volume (34.8 ± 11.5 cm³ vs. 28.1 ± 10.6 cm³, P < 0.001) and LA-EAT attenuation (−93.9 ± 5.3 HU vs. −90.4 ± 5.5 HU, P < 0.001). Multivariate regression analysis showed that age (OR = 1.040; 95%CI: 1.001–1.078, P = 0.042), LAVI (OR = 1.019; 95%CI: 1.002–1.037, P = 0.032), LA-EAT volume (OR = 1.193; 95%CI: 1.015–1.402, P = 0.034) and attenuation value (OR = 0.801; 95%CI: 0.701–0.916 P = 0.001) were independent predictors of LVZ. After LA-EAT attenuation was incorporated into the clinical model, the comprehensive discrimination and net reclassification tended to improve (IDI and NRI > 0, P < 0.05).

Conclusion

LA-EAT volume and attenuation values can independently predict the presence of LVZ, and LA-EAT attenuation has a better predictive value than LA-EAT volume.

Posterior left atrial epicardial adipose tissue: scope of the problem and impact of new technology

PURPOSE OF REVIEW

Patients with persistent forms of atrial fibrillation are seeking treatments based on the promise of better restoration of sinus rhythm with newer therapies. Successful catheter ablation and maintenance of atrial fibrillation in this subgroup is negatively impacted by the presence of epicardial adipose tissue (EAT) associated with the posterior left atrium.

RECENT FINDINGS

EAT is now understood to be hormonally active and promotes adverse atrial remodelling, including fibrosis and myopathy. Despite being dominantly adipose tissue, it is known to be electrically active, comprising ganglia, neural tissue and ectopic atrial myocardium that may contribute to endo-epicardial dissociation and persistent electrical activity and atrial fibrillation despite good endocardial electrical silencing. Hybrid procedures that include direct epicardial ablation of the posterior wall, including the EAT, are associated with superior outcomes in nonparoxysmal atrial fibrillation.

SUMMARY

Therapies for persistent atrial fibrillation that also ablate the EAT as part of a well tolerated transmural posterior wall ablation may improve outcomes in this challenging subset of patients.

Pericardial fat volume and incident atrial fibrillation in the Multi-Ethnic Study of Atherosclerosis and Jackson Heart Study

OBJECTIVE

To determine whether greater pericardial fat volume would be associated with increased risk of incident atrial fibrillation (AF).

METHODS

In the Multi-Ethnic Study of Atherosclerosis and Jackson Heart Study, pericardial fat volume was quantified by computed tomography. Incident AF was identified from discharge diagnosis codes, study electrocardiograms, and Medicare claims.

RESULTS

Among 7,991 participants, 40% were African American, 32% white, 18% Hispanic, and 10% Chinese American; mean age was 62 years; 55% were women. During an average of 10.0 years of follow-up in the Multi-Ethnic Study of Atherosclerosis and 4.5 years in the Jackson Heart Study, 756 incident AF cases were identified. After adjustment for age, sex, study, race/ethnicity, height, glucose status, systolic blood pressure, treated hypertension, and BMI, greater pericardial fat volume was associated with higher AF risk in Hispanics (hazard ratio 1.24 per SD, 95% confidence interval 1.05-1.46) but not overall (hazard ratio 1.06, 95% confidence interval 0.97-1.15). In mediation analysis, pericardial fat volume partially mediated the association of BMI with incident AF in Hispanics.

CONCLUSIONS

After adjustment for BMI, greater pericardial fat volume was associated with incident AF in Hispanics but not overall. Additional research is needed on the mechanisms by which pericardial fat volume is related to increased AF risk and possible differences by race/ethnicity.