Abstract
Ablative pulmonary vein isolation (PVI) decreases pulmonary vein (PV) and left atrial (LA) dimensions in atrial fibrillation (AF) patients. These changes are attributed to reverse structural remodeling following sinus rhythm restoration but evidence is lacking. We hypothesized that the downsizing is directly caused by the ablative energy and subsequent scar formation. We studied cardiac magnetic resonance imaging in 21 paroxysmal AF patients before and 3months after successful PVI and in healthy sheep (n=12) before and after PVI of the right PV only. PVI decreased the PV diameter in patients and sheep by 11.0(10.3) and 9.2(11.0)%, (p<0.001 and p=0.020), respectively. The control left PV in sheep were unchanged. A linear correlation existed between the extent of PV scar and PVI-induced decrease in PV diameter in patients.After PVI, the LA volume decreased (103(38) vs. 92(31)ml, pre- vs. post-ablation, respectively, p=0.006), while the right atrial (RA) volume was unchanged in patients. A decrease in active emptying fraction after ablation (26.5(10.7) vs. 21.8(10.6)%, pre- vs. post-ablation, p=0.031) was associated with reduced contractility of the PV walls (p=0.004). The contractility of the LA walls was unaltered (p=0.749). The ablation-induced PV diameter reduction was similar in patients with AF and healthy sheep without AF and was associated with PV scar extent. The volume only decreased in LA and not RA after PVI, and wall contractility decreased only in ablated sites. Therefore, the PVI-induced atrial downsizing is caused by the ablative energy and subsequent scar formation.
Highlights
Atrial fibrillation (AF) initiates a structural remodeling of the atrial myocardium involving loss of contractile fibers and an increase in interstitial collagen accumulation [1,2]
Successful pulmonary vein isolation (PVI) ablation causes a decrease in pulmonary vein (PV) and left atrial (LA) dimensions within months after the ablation procedure. [6,7,8] This reduction in PV and LA dimensions is attributed to a decrease in atrial fibrillation (AF) burden and thereby reverse structural remodeling in the atria. [9,10,11,12] Reverse remodeling is a return towards the pre-disease state and in volves the decrease of structural
We tested this in patients with paroxysmal AF that were successfully treated with PVI ablation and in sheep without AF, and provide evidence that the changes in LA and PV diameter are the result of the ablative energy delivery and subsequent scar formation and not of reverse remodeling induced by decreased AF-burden
Summary
Atrial fibrillation (AF) initiates a structural remodeling of the atrial myocardium involving loss of contractile fibers and an increase in interstitial collagen accumulation (fibrosis) [1,2]. We anticipated that reverse structural remodeling initiated by normalization of the cardiac rhythm 1) only occurs in the setting of AF remodeling, 2) takes place in the LA and right atrium (RA), 3) is characterized by an increase in contractile fibers and thereby contractility, and 4) exert an effect on LA dimensions in all cardiac phases We tested this in patients with paroxysmal AF that were successfully treated with PVI ablation and in sheep without AF, and provide evidence that the changes in LA and PV diameter are the result of the ablative energy delivery and subsequent scar formation and not of reverse remodeling induced by decreased AF-burden. Ablative pulmonary vein isolation (PVI) decreases pulmonary vein (PV) and left atrial (LA) di mensions in atrial fibrillation (AF) patients These changes are attributed to reverse structural remodeling following sinus rhythm restoration but evidence is lacking. The PVI-induced atrial downsizing is caused by the ablative energy and subsequent scar formation
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