In a multicenter cohort of patients with PAF and Pers-AF, PVI with the novel RFB catheter was safe, efficient, and resulted in a high rate of freedom from recurrent atrial arrhythmias. ERAT was the only predictor of late recurrence (Central Illustration).

This study represents the first multicenter real-word prospective analysis of acute and long-term outcome of patients undergoing RFB-based PVI. In this cohort of patients, RFB-PVI was performed with a 100% acute success rate; the Kaplan–Meier estimates for freedom from atrial tachyarrhythmias were 78.4% for PAF and 75.4% for Pers-AF. This success rate is slightly higher when compared to the SHINE study [7] that evaluated the outcome of RF-PVI in a group of patients with PAF only. Our results are also comparable to other established and emerging energies: in the recent ADVENT trial, modern RF point-by-point ablation, cryoballoon ablation, and the newly introduced pulsed field ablation led to a 1-year follow-up in paroxysmal AF between 71 and 73% [8].

The favorable long-term clinical outcomes were achieved by considerably short procedure times with a median procedure time of 67 min, and a median LA time of only 47.5 min. These data are comparable to data published about the well-established 4th generation cryoballoon [10], but also with the average procedural time recorded with a single-shot PFA device in a large European registry [11].

The rate of single-shot PVI is in line with what has been observed in acute efficacy studies [9,10,11,12]. However, contrary to our expectations, PVI obtained by single-shot RF applications did not impact long-term FU outcomes.

The LSPV, as previously described [5, 9], presented the highest rate of non-sustained block and lowest rate of single-shot isolation. Accordingly, the LSPV was also the PV with the highest rate of electrical reconduction during repeat ablation procedures in patients with AF recurrences. This might be reflected by the frequently challenging anatomy of this specific PV making it more difficult to obtain perfect circumferential balloon-to-PV contact and thus optimal balloon-tissue energy transfer.

Single-shot devices are designed to simplify PVI procedures, but they often rely primarily on fluoroscopy guidance. This system, however, was launched with integrated 3D mapping, which enhances catheter visualization, positioning at the PV ostium, and navigation in the LA, especially compared to other balloon techniques. Impedance and temperature values can be used as a surrogate of circumferential contact of the balloon with the PV ostium, without the need for occlusion angiograms [5]. The integration into 3D mapping provides additional information on the electrical substrate of the left atrium, while reducing radiation exposure. Moreover, the system enables real-time monitoring of ablation parameters at the side of the 3D mapping (Fig. 1). By continuously confirming tissue contact and recording electrograms, the RF balloon provides feedback to the operator, enabling precise energy titration and selective ablation in cases of electrical gaps. Consequently, the catheter’s position can be adjusted based on the information obtained. Although the associated costs can be in specific settings high, the potential benefits may justify the additional expense in selected clinical scenarios.

In the current series, RFB-PVI was safe, with a complication rate in line with other technologies, like cryoballoon or point-by-point RF-PVI [13]. The cumulative rate of safety events during FU was 3%, consisting of only 1 non-serious bleeding, 1 NSTEMI, and 1 death of non-cardiac cause. The favorable safety profile observed can be attributed to the benefits of an over-the-wire (Lasso) balloon technology allowing for safe manipulation and maneuvering inside the LA. In addition, with the energy levels selected (15 W × 60 s), we have never recorded steam pops. There were no further major safety events during follow-up, including no phrenic nerve palsy, PV stenosis, or TIA/stroke.

In the present structured follow-up, no patients experienced dysphagia or other symptoms suggestive of severe esophageal involvement. However, in this study, routine post-ablation endoscopy was not performed. RF energy delivery at the posterior portion of the PV antrum may lead to esophageal lesions, and in the worst-case scenario to esophageal fistulas. At the time of writing this manuscript, an urgent field safety notice has been issued by the manufacturer concerning atrio-esophageal fistulas. In our previous work on acute efficacy and safety of this technology, an esophageal endoscopy was performed in unselected 85 patients after a median of 1 day after the procedure. Seven thermic endoscopy-detected esophageal lesions (EDEL) (8%) were recorded, all consisting in ulcers of 0.2–1 cm in diameter. The biggest ulcer was described in a patient with a marked temperature rise (47 °C) during ablation at the LIPV, when the esophageal probe acoustic alarm did not work properly. A control endoscopy after 4 weeks revealed an almost complete healing of this lesion. Six out of seven patients (86%) with EDEL had a temperature rise in the esophagus, vs. 31/78 (40%) patients without EDEL. Patients with EDEL were in trend treated with more applications at the left-sided PVs (7 ± 3 vs. 4 ± 3, p = 0.07), with significantly more applications at the LSPV (5 ± 3 vs. 2 ± 2, p = 0.04) compared to patients without EDEL. Procedural time in patients with EDEL was significantly longer [9].

The risk of esophageal lesions may be avoided by a new non-thermal energy source as the PFA. Future evolution of the RFB technology maybe enabling a toggling between RFC and PFA could further increase the safety and efficacy profile of this platform.

ERAT are demonstrated in almost every third patient after RFB-PVI at the first FU visit. The early pro-arrhythmogenic effect of RF ablation has been largely discussed in literature and relates to ischemia, coagulation necrosis, edema, and local inflammation of atrial tissue [14, 15]. Non-optimal energy transfer at specific PVs and specific aspects of the PVs might result in sub-optimal energy transfer and thus potentially in early electrical reconduction into acutely isolated PVs. ERAT has been described as a predictor of late recurrences after point-by-point RF ablation and for cryoablation [16,17,18]. Our data underlie the fact that, also for the novel RFB, ERAT are prognostically important for the long-term outcome of PVI procedures. These findings question the practice of ignoring AF recurrences in the first 90 days after AF ablation (“blanking period”).

Other factors that are used to identify patients at high risk of recurrent AF, e.g., enlarged left atria, persistent AF, or a long duration of AF prior to AF ablation [1, 19, 20], were not associated with recurrent AF in this study. While our analysis, limited to 99 patients, cannot rule out an effect of these parameters on recurrent AF, such effects were weak in our data set.