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Introduction: Local impedance (LI) drops during radiofrequency ablation can predict lesion formation. Some conduction gaps during pulmonary vein isolation (PVI) can be associated with nonendocardial connections. This study aimed to investigate the incidence, characteristics, and predictors of endocardial and nonendocardial conduction gaps during an LI‐guided PVI. Methods and Results: We prospectively enrolled 157 consecutive patients undergoing an initial LI‐guided extensive PVI of atrial fibrillation (AF). After the first‐pass encirclement, the residual conduction gaps and reconnected gaps were mapped using Rhythmia (Boston Scientific) and a mini‐basket catheter. Right and left PV (RPV/LPV) gaps were observed in 22.3% and 18.5% of the patients, respectively: 27 endocardial and 49 nonendocardial gaps. The carina regions were common sites for the gaps (51 carina‐related vs. 25 noncarina‐related). The carina‐related gaps consisted of more nonendocardial gaps than endocardial gaps (RPVs: 90.0% vs. 10.0%, p =.001; LPVs: 76.2% vs. 23.8%, p <.001). A univariate analysis revealed that paroxysmal AF and the left atrial (LA) volume index for RPV endocardial gaps (odds ratio [OR]: 8.640 and 0.946; p =.043 and 0.009), minor right inferior PV diameter for RPV nonendocardial gaps (OR: 1.165; p =.028), and major left inferior PV diameter for LPV endocardial gaps (OR: 1.233; p =.028) were significant predictors. Conclusions: During the LI‐guided PVI, approximately two‐thirds of the conduction gaps were nonendocardial. The carina regions had more conduction gaps than noncarina regions, which was due to the presence of nonendocardial connections. Paroxysmal AF, a lower LA volume index, and larger inferior PV diameters may increase the risk of conduction gaps. [ABSTRACT FROM AUTHOR]

Background: Air bubble intrusion through transseptal sheaths during left atrial (LA) catheter ablation can cause cerebral embolisms, especially when using complex‐shape catheters. This study aimed to compare the incidence of silent cerebral events (SCEs) after atrial fibrillation (AF) catheter ablation using a mini‐basket catheter (IntellaMap Orion; Boston Scientific) between the following groups: group SP, strict prevention of LA air intrusion and group CP, conventional air intrusion prevention. Methods: We enrolled 123 consecutive AF patients (group SP, n = 61 and group CP, n = 62) who underwent brain magnetic resonance imaging after a local‐impedance‐guided ablation using one mini‐basket catheter and one circular mapping catheter. The preventive strategy in group SP included (a) the insertion of the mini‐basket catheter into the transseptal sheaths in a container filled with heparinized saline and (b) no exchange of all catheters over the sheaths. Results: SCEs were detected in 67 patients (54.5%), and the incidence of SCEs did not significantly differ between groups SP and CP (55.7% vs 53.2%; P =.780). A multivariate analysis demonstrated that an older age, non‐paroxysmal AF, and radiofrequency (RF) power output were independent positive predictors of SCEs (odds ratios: 1.079, 5.613, and 1.405; P =.005, <.001, and.012). On the follow‐up MR imaging, 83.5% of the SCEs in group SP and 87.7% in group CP disappeared (P =.398). Conclusions: Strict prevention of LA air intrusion may have no additional effect for reducing the incidence of SCEs after local impedance‐guided AF ablation using a mini‐basket catheter. An older age, non‐paroxysmal AF, and high‐power RF applications may increase the risk of SCEs. [ABSTRACT FROM AUTHOR]

Introduction: The difference in the incidence and characteristics of silent cerebral events (SCEs) after radiofrequency‐based atrial fibrillation (AF) ablation between the different mapping catheters and indices used for guiding radiofrequency ablation remains unclear. This study aimed to compare the incidence and characteristics of postablation SCEs between the following two groups: Group C, Ablation Index‐guided ablation using two circular mapping catheters with CARTO (Biosense Webster); Group R, local impedance‐guided ablation using one mini‐basket catheter and one circular mapping with Rhythmia (Boston Scientific). Methods and Results: Of 211 consecutive patients who underwent an AF ablation and brain magnetic resonance (MR) imaging after the ablation, 120 patients (each group, n = 60) were selected by propensity score matching. SCEs were detected in 37 patients (30.8%). Group R had a higher incidence of SCEs (51.7% vs. 10.0%; p <.001) and more SCEs per patient (median, 3 vs. 1, p =.028) than Group C. A multivariate analysis demonstrated that nonparoxysmal AF and being Group R were independent positive predictors of SCEs (odds ratios, 6.930 and 15.464; both p <.001). On the follow‐up MR imaging, all SCEs in Group C and 87.9% of the SCEs in Group R disappeared (p =.537). Conclusions: Group R had a significantly higher incidence of SCEs than Group C. Most probably the use of a complexly designed basket mapping catheter is the reason for the difference in the incidence of SCEs but further validation is needed. A nonparoxysmal form of AF may also increase the risk of SCEs during these ablation procedures. [ABSTRACT FROM AUTHOR]