Utility of hot-balloon-based pulmonary vein isolation under balloon surface temperature monitoring: First clinical experience

Balloon surface temperature-controlled ablation using a second-generation radiofrequency HotBalloon: an in vivo feasibility study

AIMS

The first-generation radiofrequency HotBalloon (RHB) is a size-adjustable single-shot device used in atrial fibrillation. The energy output is determined by its central temperature and not by its balloon surface temperature (BST), thus limiting its efficacy and safety. Therefore, a second-generation RHB was developed to monitor BST and enable BST-controlled ablation. This animal study aims to evaluate the accuracy of a newly developed BST-monitoring system and validate the optimal BST for ablation.

METHODS AND RESULTS

In Protocol 1, thermocapsules were attached to the superior vena cava (SVC) epicardium. The accuracy of BST monitoring was examined during SVC isolation. In Protocol 2, the efficacy and safety of different BST-controlled ablations were examined. In the acute model, electrophysiological and pathological findings were assessed after energy applications with BST at 51, 54, 57, and 60°C. In the chronic model, the lesion durability and pathological findings were assessed 8 weeks after BST-controlled ablation (57 and 60°C). A significant positive correlation was found between the epicardial temperature and the BST-monitoring value (r = 0.98). In the acute model, all target veins were electrically isolated with BST-controlled ablation at ≥57°C (18/18, 100%). In the chronic model, durable lesions were observed in all veins at 60°C, while 44% of the veins showed reconnection at 57°C. In both pathological analyses, significantly greater lesions were observed at 60°C than at 57°C. There were no significant differences in adverse events between the two groups.

CONCLUSION

Balloon surface temperature-controlled ablation at 60°C using the second-generation RHB may be optimal for creating durable lesions without compromising safety.

HotBalloon Pulmonary Vein Isolation Registry Study - Real-World Efficacy and Safety of HotBalloon Ablation

BACKGROUND

Radiofrequency hotballoon (RHB) is an ablation device used for atrial fibrillation (AF) treatment. The efficacy and safety of RHB-based pulmonary vein isolation (PVI) in real-world practice are unknown.Methods and Results: A multicenter, prospective registry study (UMIN000029567) enrolled AF patients who underwent RHB-PVI. The primary endpoint was the AF recurrence-free survival rate at 12 months after PVI. Of the 679 patients enrolled, 613 (90.3%; paroxysmal AF, n=370; persistent AF, n=136; long-standing AF, n=107) underwent initial RHB-PVI. Acute isolation using only the RHB was successful for 55.6% of patients and 83.5% of pulmonary veins (PVs). The acute isolation rate was higher for patients with paroxysmal AF and more experienced centers. Antiarrhythmic drugs were prescribed after 3 months for 47.5% of patients. The AF recurrence-free survival rate at 12 months was 83.7%. Procedure-related complications including atrio-esophageal fistula (n=1) and phrenic nerve injury (persistent; n=4, permanent; n=2) were observed in 19 (3.1%) patients. Five (1.7%) of the 302 patients who underwent pre-procedural and post-procedural multidetector computed tomography had severe PV stenosis.

CONCLUSIONS

The size-adjustable RHB has been used for the treatment of various AF types. The arrhythmia recurrence-free rate at 12 months, with the use of antiarrhythmic drugs in approximately half of the patients, was acceptable, but the acute isolation rate using the RHB requires further improvement.

Comparison of phrenic nerve injury and its effect on the extrapulmonary vein structures with cryoballoon and hot-balloon ablation systems: considering the lesion created on the superior vena cava as a surrogate marker

Preventing phrenic nerve injury (PNI) during balloon-based ablation is essential. The superior vena cava-right atrial (SVC-RA) junction is located just opposite the balloon position during right superior pulmonary vein (RSPV) ablation, and the phrenic nerve runs nearby on the lateral side. We compared the occurrence of PNI between the two balloon-based ablation systems and also the lesions created at the SVC-RA junction, which were expected to represent the effect on extra-PV structures. Cryoballoon ablation (CBA, n = 110) and hot-balloon ablation (HBA, n = 90) were performed in atrial fibrillation patients. High-density maps of the SVC-RA junction were created in 93 patients (CBA = 53, HBA = 40), and the damaged area (< 1.0 mV) was determined as an "SVC lesion". CBA had a higher occurrence of transient PNI (7.3% vs 1.1%, p = 0.035), but all recovered during the 6-month follow-up. An apparent SVC lesion was documented in 43% of the patients (40/93), and all patients with PNI had this lesion. CBA created a frequent (CBA vs HBA = 55% vs 28%, p = 0.008) and wider (0.8[0.4-1.7] cm² vs 0.5[0.3-0.7] cm², p = 0.005) SVC lesion than HBA. A multivariate analysis revealed that the use of a CBA system was a predictive factor of the occurrence of SVC lesions. CBA had a higher occurrence of transient PNI but not a permanent form. Every patient with PNI had lesions on the SVC-RA junction, and CBA revealed more substantial ablation effects at the SVC-RA junction than HBA. This may be caused by the different characteristics of the two balloon-based ablation systems and their balloon positions.

Percutaneous Treatment Approaches in Atrial Fibrillation: Current Landscape and Future Perspectives

Atrial fibrillation (AF), the most common sustained arrhythmia in clinical practice, represents a major cause of morbidity and mortality, with an increasing prevalence. Pharmacologic treatment remains the cornerstone of its management through rhythm and rate control, as well as the prevention of thromboembolism with the use of oral anticoagulants. Recent progress in percutaneous interventional approaches have provided additional options in the therapeutic arsenal, however. The use of the different catheter ablation techniques can now lead to long arrhythmia-free intervals and significantly lower AF burden, thus reducing the rate of its complications. Particularly encouraging evidence is now available for patients with persistent AF or concomitant heart failure, situations in which catheter ablation could even be a first-line option. In the field of stroke prevention, targeting the left atrial appendage with percutaneous device implantation may reduce the risk of thromboembolism to lower rates than that predicted with conventional ischemic risk scores. Left atrial appendage occlusion through the approved Watchman or Amplatzer devices is a well-established, efficacious, and safe method, especially in high-ischemic and bleeding risk patients with contraindications for oral anticoagulation.

Radiofrequency Current Versus Balloon-Based Ablation for Atrial Fibrillation

The basis for selection of contemporary ablation technologies for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remains unclear. We compared procedural data and efficacy in a propensity score-matched cohort treated with 4 ablation technologies in a center mainly using cryoballoon (CB). A total of 819 consecutive patients with AF underwent PVI, using radiofrequency current (RFC) (65 patients), CB (693 patients), hot balloon (HB) (74 patients), and laser balloon (LB) (52 patients). A total of patients (82% paroxysmal AF) were selected from each group according to the propensity score. Procedural data and freedom from atrial tachyarrhythmia recurrence after the index procedure were compared. All pulmonary veins were isolated in all groups. Procedure time was shorter in CB and HB groups (RFC: 148 ± 53 vs CB: 85 ± 37 vs HB: 102 ± 31 vs LB: 140 ± 28 minutes, p <0.001). RFC touch-up was most commonly required for PVI in the HB group among balloon groups (40%) (p <0.001). Total complication rate was 4% to 18% without any statistical differences between groups (p = 0.123). Phrenic nerve injury occurred most often in the CB group (16%) (p <0.001). During a mean follow-up of 21 ± 6 months, there were no significant differences among groups for freedom from atrial tachyarrhythmia recurrence after the index procedure (RFC: 68% vs CB: 78% vs HB: 76% vs LB: 76%, p = 0.440). In conclusion, all the ablation technologies facilitate safe and efficient PVI, with slight differences in the procedural data and complications.

Evaluation of linear lesion formation and thermodynamics by dragging ablation with the third-generation laser balloon

Background

The lesion formation properties of a motorized rotational delivery (RAPID) mode, third-generation laser balloon (LB3) ablation compared to point-by-point laser ablation in patients with atrial fibrillation remain unclear.

Objective

The purpose of this study was to assess lesion characteristics and thermodynamics in LB3 ablation with a RAPID mode in vitro model.

Methods

Chicken muscles were cauterized using LB3 in RAPID mode with 13 W and 15 W and 50% overlapped point-by-point fashion with 7 W/30 seconds, 8.5 W/20 seconds, 10 W/20 seconds, and 12 W/20 seconds. Lesion depth, width, and continuity were compared. Lesion continuity was classified by the visible gap degree categorized from 1 (perfect) to 3 (poor). Thermodynamics and maximum tissue temperatures were assessed under infrared thermographic monitoring. Fifteen and 5 lesions were evaluated per ablation protocol for measurement of lesion size and continuity and for thermographic assessment, respectively.

Results

Lesion depth and width were smaller in RAPID mode laser ablation than point-by-point laser ablation (P <.001). However, RAPID mode laser ablation revealed sufficient mean lesion depth of 5 mm or more. Lesion continuity was 1 (perfect) in all samples in RAPID mode laser ablation and point-by-point laser ablation (P = 1). Infrared thermographic observation demonstrated fast and gapless linear lesion formation with thermal stacking in RAPID mode laser ablation. Maximum tissue temperature was lower in RAPID mode laser ablation than point-by-point laser ablation (P <.001).

Conclusion

RAPID mode LB3 ablation could provide fast, gapless, and acceptable lesion formation with thermal stacking and moderate tissue temperature rise.