Analysis of the preferable site and stability of rotational reentry: its role for the maintenance of atrial fibrillation

Evaluating spatial disparities of rotor sites and high dominant frequency regions during catheter ablation for PersAF patients targeting high dominant frequency sites using non-contacting mapping

Purpose: Several studies have emphasised the significance of high dominant frequency (HDF) and rotors in the perpetuation of AF. However, the co-localisation relationship between both attributes is not completely understood yet. In this study, we aim to evaluate the spatial distributions of HDF regions and rotor sites within the left atrium (LA) pre and post HDF-guided ablation in PersAF. Methods: This study involved 10 PersAF patients undergoing catheter ablation targeting HDF regions in the LA. 2048-channels of atrial electrograms (AEG) were collected pre- and post-ablation using a non-contact array (EnSite, Abbott). The dominant frequency (DF, 4-10 Hz) areas with DF within 0.25 Hz of the maximum out of the 2048 points were defined as "high" DF (HDF). Rotors were defined as PSs that last more than 100 ms and at a similar location through subsequent phase frames over time. Results: The results indicated an extremely poor spatial correlation between the HDF regions and sites of the rotors in pre-versus post-ablation cases for the non-terminated (pre: CORR; 0.05 ± 0.17. vs. post: CORR; -0.030 ± 0.19, and with terminated patients (pre: CORR; -0.016 ± 0.03. post: CORR; -0.022 ± 0.04). Rotors associated with AF terminations had a long-lasting life-span post-ablation (non-terminated vs. terminated 120.7 ± 6.5 ms vs. 139.9 ± 39.8 ms), high core velocity (1.35 ± 1.3 mm/ms vs. 1.32 ± 0.9 mm/ms), and were less meandering (3.4 ± 3.04 mm vs. 1.5 ± 1.2 mm). Although the results suggest a poor spatial overlapping between rotors' sites and sites of AFCL changes in terminated and non-terminated patients, a higher correlation was determined in terminated patients (spatial overlapping percentage pre: 25 ± 4.2% vs. 17 ± 3.8% vs. post: 8 ± 4.2% vs. 3.7 ± 1.7% p < 0.05, respectively). Conclusion: Using non-contact AEG, it was noted that the correlation is poor between the spatial distribution of HDF regions and sites of rotors. Rotors were longer-lasting, faster and more stationary in patients with AF termination post-ablation. Rotors sites demonstrated poor spatial overlapping with sites of AFCL changes that lead to AF termination.

Identification of high priority focal activations in persistent atrial fibrillation using a novel mapping strategy

Focal activation is believed to be an atrial fibrillation (AF) driver; however, little is known about whether all focal activations are necessary for AF persistence. The purpose of this study was to assess the electrical nature of focal activation and identify high-priority focal activations using a novel mapping system (CARTOFINDER). Thirty-five patients with persistent AF who underwent catheter ablation were assessed. Cycle length (CL) and CL standard deviation (CLSD) on unipolar recordings and voltage amplitude and electrogram morphologies on bipolar recordings were evaluated at all points of interest. The most frequent CL at each mapping site was defined as the dominant CL. We identified dominant focal activations (DFAs) that had a shorter dominant CL on the integrated CARTOFINDER map. The effect of elimination of DFAs on AF maintenance was assessed by the composite endpoint (termination to sinus rhythm, organization of the rhythm to atrial tachycardia, and AF CL slowing). In all, 450 focal activations were identified among 10,868 points, and 50.4% of focal activations were DFAs. Focal activations showed relatively long CL and regularity with short CLSD. Most focal activations showed an isoelectric baseline and were located outside of the fractionated electrogram area. Both DFAs and non-DFAs were typically observed in the normal voltage range. Elimination of DFAs was achieved in 19 (54.3%) patients, with a remarkable impact on AF maintenance (68.4% vs. 25.0%, p = 0.018). In conclusion, DFAs may play an important role in AF maintenance and could be an attractive therapeutic target for AF.

Comparison of the catheter ablation outcome in patients between targeting the entrance and exit of the reentry circuit in verapamil-sensitive atrial tachycardia originating from the atrioventricular-node vicinity

Verapamil-sensitive atrial tachycardia originating from the atrioventricular node vicinity (AVN-AT) can be eliminated with radiofrequency energy (RF) deliveries targeting either the entrance or exit of its reentry circuit. However, the outcome of these different approaches has not been clarified well. Thus, we compared the catheter ablation outcome targeting the entrance of reentry circuit, identified by the entrainment method (Ent-Group; 21 patients) with that targeting the earliest atrial activation site (EAAS) during AT (Exit-Group; 16 patients). There was no significant difference in the tachycardia cycle length (441.4 ± 87.4 vs. 392.8 ± 64.8 ms, p = 0.0704) or distance from the His bundle (HB) site to the EAAS (6.5 ± 2.0 vs. 7.6 ± 1.8 mm, p = 0.0822) between the Ent- and Exit-Groups. However, distance from the successful ablation site to the HB site in the Ent-Group was significantly longer than that in the Exit-Group (13.4 ± 3.1 vs. 7.6 ± 1.8 mm, p < 0.0001), resulting in more frequent transient atrioventricular block episodes in the Exit-Group than Ent-Group (31.3 vs. 0%, p < 0.01). Initial ATs (AT1s) were terminated in all patients in both Groups. However, ATs accompanied by shifting in the EAAS (AT2) were induced more frequently in the Exit-Group than Ent-Group (50.0 vs. 14.3%, p < 0.02) after eliminating AT1. RF deliveries to the EAAS eliminated all AT2s. The number of RF deliveries was greater in the Exit-Group than Ent-Group (6.9 ± 3.3 vs. 3.9 ± 1.6, p < 0.001). In conclusion, RF ablation targeting the entrance sites can avoid AVN injury and is superior in reducing the number of RF deliveries and occurrence of different ATs than targeting the exit sites in the AVN-AT.