Structural remodelling contribute to trigger and maintenance of atrial fibrillation (AF). Epicardial adipose tissue (EAT) has been associated with AF pathogenesis. Persistent AF also contributes to the progression of AF, leading to atrial cardiomyopathy (AtCM). Despite catheter ablation, the risk of recurrence is high, especially in persistent AF. It is still a challenge to assess the stage of the AtCM non-invasively. Cardiac imaging such as echocardiography and computed tomography (CT) play a key role. The aim of our study was in patients (pts) with persistent AF 1) to search for recurrence of atrial arrhythmias (AA) after first left atrial (LA) ablation and 2) to investigate the predictive value of LA strain, EAT 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 who underwent first time LA catheter ablation (CA). All subjects underwent before CA a measurement of LA strain using 2D speckle tracking echo (2D-STE) and cardiac CT. EAT volume in total (EATtot) and at the atrial side (EATa) as well as the mediastinal adipose tissue (MEAT) were determined. The LA volume included LAA and excluded the PV´s. LAVI was calculated by dividing LA volume by body surface area. LA strain, EAT and LAVI of pts with and without atrial arrhythmia recurrence in the follow- up (FU) were compared.
Results: Baseline characteristics of all pts: average age 67 ±8 yrs, 69 male (75%), LVEF 53 ±11 %. BMI 29 ±5 kg/m². Average duration between first diagnosis (FD) and ablation were 22 ±30 months. LA strains (average LASr 19 ±11, LAScd -11±7, LASct -8 ±8 %). EATtot was 167 ±46, EATa 65 ±25, MEAT 321 ±159 ml. Density EATtot - 63 ±8, EATa - 59 ±8 and MEAT: - 79 ±18 HU. LA volume 171±48 ml, LAVI 81±48 ml/m². In a FU period up to 56 months, in 29 pts (32%) recurrences of atrial arrhythmia (AF n=10, AT n= 15, AF/ AT n= 2, typical Afla n=2) occurred on average 20 ±13 months after the index procedure. In 12 (41%) of them, a substrate modification in the LA was performed in addition to the PVI during the index procedure guided by the substrate. 26 of the recurrence pts received an intervention (cardioversion/ ablation). 19 pts underwent repeat ablation (Re- PVI n=7, Redo- lines n=5, new lines LA n=2, focal AT n=7, CTI-line n=2). Pts with recurrence did not differ significantly (p>0,05) from those without recurrence in terms of baseline characteristics (duration between FD and index ablation, age, gender, LVEF, BMI). LA strain, LAVI, EATtot, EATa, MEAT volume and density in both groups was not significantly different (p>0,05).
Discussion: In our pts, the time span between FD and first ablation is relatively long, with some pts having had AF for many years. The recurrence rates of 32% after first ablation in a long FU period correspond to those known in a pts with persistent AF. As an expression of functional remodeling the LA strain is significantly reduced compared to normal values reported. The LA´s are highly dilated as a sign of structural remodeling. LAVI, EATtot, EATa, MEAT volume and density were not significantly different in the group with AA recurrence compared to the group without. In the event of recurrence, atrial tachycardia was just as common as AF.
