Introduction The clinical efficacy and safety of hot balloon ablation (HBA) for the treatment of persistent AF (PerAF) remain unclear. We aimed to evaluate the clinical efficacy and safety of HBA versus cryoballoon ablation (CBA) as a treatment for PerAF. Methods Of 195 consecutive patients who underwent initial catheter ablation for PerAF (AF lasting for longer than 7 days but shorter than 12 months), 158 propensity score‐matched (79 HBA and 79 CBA) patients were included in our retrospective study. All patients who underwent HBA received applications of energy to the upper posterior LA wall with a larger balloon in addition to single shots to each pulmonary vein (PV) ostium, whereas those who underwent CBA received simple single‐shot applications. The electrically isolated surface area (ISA), including the PV antrum and part of the posterior LA wall, was assessed by high‐resolution mapping. Results The success of the PV isolation with balloon shots alone did not differ between HBA and CBA (81% vs. 85%; p = .52). The ISA was generally wide in both groups and significantly larger in the HBA group than in the CBA group (61 ± 16% vs. 51 ± 12%; p < .001). The incidence of procedure‐related complications did not differ significantly (HBA 4% vs. CBA 1%; p = .62) nor did the arrhythmia recurrence rate (HBA 11% vs. CBA 18% at 18 months; p = .26). Conclusion Despite the difference in protocols, HBA and CBA performed for PerAF appear comparable in terms of wide antral lesion creation, clinical efficacy, and safety. Further prospective studies, based on a unified methodology, are needed.

Introduction Hot‐balloon ablation depends solely on thermal conduction, and myocardial tissue is ablated by only conductive heating from the balloon surface. Despite growing clinical evidence of the efficacy and safety of hot‐balloon ablation for atrial fibrillation (AF), the actual tissue temperature and the mechanism of heating during such ablation has not been clarified. To determine, by means of a porcine study, the temperatures of tissues targeted during hot‐balloon ablation of AF performed with hot‐balloon set temperatures of 73°C or 70°C, in accordance with the temperatures now used clinically. Methods After a right thoracotomy, thermocouples with markers were implanted epicardially on the superior vena cava (SVC) and pulmonary veins (PVs) in six pigs. The tissue temperatures during hot‐balloon ablation (balloon set temperatures of 73°C and 70°C, 180 s/PV) were recorded, and the maximum tissue temperatures and fluoroscopically measured distance from the balloon surface to the target tissues were assessed. Results Sixteen SVC‐ and 18 PV‐targeted energy deliveries were performed. Full‐thickness circumferential PV lesions were created with all hot‐balloon applications. A significant inverse relation was found between the recorded tissue temperatures and distance (r = −.67; p < .001) from the balloon surface. No tissue temperature exceeded either of the balloon set temperatures. The best distance cutoff value for achieving lethal tissue temperatures more than 50°C was 3.6 mm. Conclusion The hot‐balloon set temperature, energy delivery time, and tissue temperature data obtained in this porcine study supported the clinical efficacy and safety of the hot‐balloon ablation as currently practiced in patients with AF.

Background: The electrophysiological characteristics of residual conduction gaps between the left atrium (LA) and pulmonary veins (PVs) after HotBalloon-based wide antral ablation (HBWA) of atrial fibrillation (AF) remain incompletely understood. This study aimed to characterize the residual gaps by means of ultra-high-resolution mapping. Methods and Results: A total of 55 AF patients underwent HBWA by a predetermined protocol (6-shot total-based antral approach). LA-PV maps were created using 64-electrode minibasket catheters. In total, 55 residual gaps were identified among 26 (47%) patients. Residual gaps included 33 left superior (LS: 60%), 10 left inferior (18%), 6 right superior (11%), and 6 right inferior (11%) PVs. Those gaps demonstrated both extremely lower bipolar amplitudes (0.11 [interquartile range: 0.06-0.27] mV) and conduction velocities (0.75±0.27 m/s); however, the length was confined (10.3±4.1 mm) except for the LSPV anterior carina (12.2±2.4 mm) region. Among the carina regions, all gaps had far-field potentials consistently added to the PV potentials. Left atrial appendage pacing to split the far-field activity identified confined gap regions (6.7±1.9 mm). Touch-up ablation eliminated the residual PV potentials in all cases. Conclusions: HBWA resulted in a certain degree of residual gap conduction in particular antral regions. These gaps exhibited narrow lengths with lower amplitudes, and often had far-field recordings from the left atrial appendage. Combined with pacing maneuvers, ultra-high-resolution activation maps could both visualize all confined gaps and ensure a bare minimum of touch-up ablations in all patients with gap conduction.

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Introduction Cryoablation has emerged as an alternative to radiofrequency ablation for treating atrioventricular nodal reentrant tachycardia (AVNRT). The aim of this prospective study was to evaluate the efficacy and safety of cryoapplication at sites within the mid/high septal region of Koch's triangle and the relation between sites of transient AV block (AVB) and sites of successful cryoablation. Methods and Results Included were 45 consecutive patients undergoing slow‐fast AVNRT cryoablation. Initial delivery of cryoenergy was to the mid‐septal to high septal region of Koch's triangle. Transient AVB occurred during cryoenergy delivery in 62% (28/45) of patients. Median distance between sites at which cryofreezing successfully eliminated slow pathway conduction and sites of AVB was 4.0 (3.25–5.0) mm. Sites of successful cryoablation tended to be to the left and inferior to the AVB sites. The atrial/ventricular electrogram ratio was significantly lower at sites of successful cryoablation than at AVB sites (0.25 [0.17–0.56] vs. 0.80 [0.36–1.25], p < .001). Delayed discrete or fractionated atrial electrograms were recorded more frequently at sites of successful cryoablation than at AVB sites (78% vs. 20%, p < .001). No persistent AV conduction disturbance occurred, and 96% (43/45) of patients showed absence of recurrence at a median follow‐up time of 25.0 months. Conclusion Cryoablation of slow‐fast AVNRT and targeting the mid/high septal region of Koch's triangle was highly successful. AVB frequently emerged near the site at which the slow pathway was eliminated but always resolved by regulating the energy delivery under careful monitoring, and it may be distinguishable by its local electrogram features.

Our data suggested that external structures in contact with the LA are involved in the creation of localized diseased myocardium necessary for PsAF maintenance.

We herein report the case of a 72-year-old man with endocarditis of the aortic valve who underwent urgent aortic valve replacement 36 hours after admission due to an aggravation of aortic valve regurgitation. Postoperative cultures of the blood and site of valve vegetation identified Candida parapsilosis as a pathogen. Antifungal therapy with amphotericin B and fluconazole was initiated after surgical treatment. Thereafter, the patient displayed a favorable clinical course. Candida parapsilosis endocarditis involving the native valves is extremely rare and associated with a very high mortality rate. Prompt surgical treatment and the aggressive use of antifungal agents are required to save the patient's life.

Introduction A new hot balloon system that registers balloon surface temperature (BST) during energy delivery is now available for clinical use in Japan. This study sought to investigate the utility of BST measurement for achievement of pulmonary vein isolation (PVI) by a single‐shot energy delivery strategy during hot balloon ablation (HBA). Methods We applied and tested the system in 30 consecutive patients undergoing HBA for paroxysmal or early‐persistent atrial fibrillation (AF). We also performed real‐time PV potential monitoring using a circular catheter. Results Acute PVI was achieved with single hot balloon shots in 88% (106/120) of the PVs. Real‐time BSTs and PV potentials were recorded in all cases. Mean BST at documentation of PVI was 49.4°C, and acute reconnections were observed in most cases (86%, 12/14) in which the single‐shot technique was ineffective. Time‐to‐isolation (TTI) (23.1 ± 8.7 s vs. 36.3 ± 9.3 s, p < .01) and median BST (59.9 ± 2.6°C vs. 55.7 ± 1.9°C, p < .01) differed significantly between cases in which PVI was achieved (vs. those in which PVI was not achieved). Multivariable analysis revealed strong association between both TTI and median BST and acute PVI. The best median BST cutoff value for achieving PVI with a single shot was >58.7°C (sensitivity 67.0%, specificity 100%). Conclusion Our data suggest that real‐time BST monitoring during energy applications is useful for predicting achievement of acute PVI by a single shot during HBA.