Interatrial septal thickness as a marker of structural and functional remodeling of the left atrium in patients with atrial fibrillation.

BACKGROUND/AIMS: There have been reports that interatrial septal (IAS) thickness is increased in patients with atrial fibrillation (AF). This study was performed to investigate whether IAS thickness determined by transthoracic echocardiography (TTE) represents the amount of left atrium (LA) structural and functional remodeling. METHODS: The study population consisted of 104 consecutive patients who underwent catheter ablation (CA) for AF (paroxysmal atrial fibrillation [PAF], 82; persistent atrial fibrillation [PeAF], 22). IAS thickness and left atrium volume (LAV) using TTE, and LA voltage (LA(VOL)) using 3-dimensional electroanatomical mapping system were assessed during sinus rhythm. RESULTS: IAS thickness was significantly correlated with maximal LAV (LAV(max)) (r = 0.288, p = 0.003), mean LA(VOL) (r = -0.537, p < 0.001), total left atrium emptying fraction (LAEF(total); r = -0.213, p = 0.030), and active LAEF (LAEF(active); r = -0.249, p = 0.014). IAS thickness was greater in the high-risk group (≥ 2) compared to other groups according to CHA2DS2-VASc score (p = 0.019). During a follow-up of 19.6 months, 23 subjects (22.1%; PAF, 17; PeAF, 6) had recurrence of arrhythmia. Univariate analysis showed that LAV(max), minimal LAV, mean LA(VOL), LVEF(total), LVEF(active), and IAS thickness were associated with recurrence of arrhythmia. However, on multivariate analysis, only mean LA(VOL) and LAEF(active) were independent risk factors for recurrence. CONCLUSIONS: Although IAS thickness showed significant correlations with parameters for LA structural and functional remodeling, this parameter alone could not independently predict recurrence of arrhythmia after CA for AF.

Does the amount of atrial mass reduction improve clinical outcomes after radiofrequency catheter ablation for long-standing persistent atrial fibrillation? Comparison between linear ablation and defragmentation.

BACKGROUND: Although a large isolated surface area of the left atrium (LA) may improve the success rate of catheter ablation (CA) for paroxysmal atrial fibrillation (AF), little is known about the relation between clinical outcomes and the amount of atrial mass reduction (AMR: ratio of total isolated and ablated areas to LA surface area) in different ablation strategies for patients with long-standing persistent AF (L-PeAF). METHODS: We randomly assigned 119 consecutive L-PeAF patients to adjunctive linear ablation (n=60) or complex fractionated atrial electrogram (CFAE)-guided ablation (n=59) after circumferential antral pulmonary vein isolation (PVI). Linear lesions included roof and anterior lines with conduction block. LA defragmentation was performed with an automated CFAE-detection algorithm. Cavotricuspid isthmus block was performed in all patients. Creatine kinase-MB (CK-MB) and troponin-T levels were measured 1 day post-CA. RESULTS: CK-MB and troponin-T levels were higher, ablation time was longer, and AMR was greater in the CFAE-guided ablation group than in the linear ablation group. AF termination during CA was more frequently observed in the linear ablation group than in the CFAE-guided ablation group (P=0.031). Twelve months after a single procedure, recurrence occurred in 16 (26.7%) patients with linear ablation and 27 (45.8%) patients with CFAE-guided ablation (P=0.023). On multivariate analysis, LA volume and ablation method were the only independent risk factors for arrhythmia recurrence. CONCLUSION: Conduction block through linear lines+PVI was an efficient ablation strategy for L-PeAF, whereas the AMR amount did not influence clinical outcomes.