Background: Atrial cardiomyopathy (AtCM) may manifest with atrial arrhythmias and findings consistent with atrial dysfunction or structural abnormalities. Several studies suggested a role of epicardial adipose tissue (EAT) in the development of atrial fibrillation (AF). It is still a challenge to assess the stage of the AtCM non-invasively. Cardiac imaging such as echocardiography and ecg-synchronized computed tomography (CT) play a key role.
The aim of our study was in patient with persistent AF 1) the echocardiographic assessment of LA function using LA strain, 2) to investigate the correlation between LA strain, EAT analysis and the left atrial size index (LAVI) obtained from the CT as a possible tool to assess the extent of AtCM.
Methods: This study includes 92 pts with persistent AF (AF group) who underwent first time LA catheter ablation and 43 pts without structural heart disease or AF who underwent EP study (control group). All subjects underwent measurement of LA strain using two-dimensional speckle tracking echocardiography (2D-STE) and the pts with AF underwent cardiac CT as well. EAT volume in total (EATtot) and at the atrial side (EATa) as well as the mediastinal adipose tissue (MAT) were determined blinded to strain findings The LA volume included LAA and excluded the PV´s. LAVI was calculated by dividing LA volume by body surface area.
Results: AF group: average age 67 ± 8 yrs, 69 male (75%), LV-EF 53 ± 11 %, BMI 29 ± 5 kg/m². Average duration between first diagnosis of AF and ablation 22 months. Control group: average age 60 ± 13 yrs, 23 male (53%), LV- EF 63 ± 7 %. BMI 28 ±6 kg/m². All the different LA strains (average LASr 19 ± 11 vs. 39 ± 10, LAScd -11 ± 7 vs. -22 ± 8, mean LASct -8 ± 8 vs. -17 ± 8 %) were significantly worse (p< 0,001) in the pts with persistent AF in comparison to the control group.
In the AF group the EATtot volume was 167 ± 46 ml, the EATa volume 65 ± 25 ml. Both- EATtot and EATa volume are strongly correlated (r= 0,8, p< 0,001) to the MAT volume (321 ± 159 ml). The BMI shows a significant positive correlation (r= 0,5, p< 0,001) to the volume of all three compartments.
The LAVI (average 81 ± 48 ml/m²) is not correlated (r= 0,1) to the adipose tissue volume. In contrast the LAVI is negative correlated (r=- 0,4, p< 0,001) to the density of the EATa and positive (r=0,3, p< 0,001) to LA strain. There was no correlation between EAT volume / density and the LA strain.
Discussion: As an expression of functional remodeling LA strain in pts with persistent AF is significantly reduced compared to pts without structural heart disease or AF. The LAVI, as an expression of LA dilation, correlates well with LA strain. None of this correlates with selective (atrial/total) EAT, neither volume nor density. Therefore, no additional value of a quantitative analysis of EAT for the diagnosis of AtCM at this stage of the disease is observable.
