Background: The multielectrode radiofrequency (RF) balloon catheter (HELIOSTAR^TM, Biosense Webster) is an innovative technology for pulmonary vein isolation (PVI) in atrial fibrillation (AF). RF-ablation and 3D-mapping are combined with the concept of a “single-shot”-ablation device which may reduce procedure time and manual complexity in operator training. This study evaluates the clinical outcome in a real-world, “all-comers” cohort during implementation of the multielectrode RF-balloon at a high-volume ablation center.

 

Methods: The first 40 patients (67% paroxysmal AF, 33% persistent AF) undergoing PVI by the multielectrode RF-balloon catheter at Heidelberg University Hospital were included in this observational study. The procedure was performed according to the center’s standards and in line with the manufacturer’s instructions as to handling the device. Acute efficacy and procedure-associated complications were recorded. Patients were enrolled in a prospective registry and underwent follow-up visits at 3 months at the outpatient clinic, as well as telephone-based follow-ups at 6 and 12 months. At follow-up, patients were systematically interviewed regarding post-procedural complications, recurrent symptomatic or documented arrhythmia and unscheduled visits to medical services in relation to cardiovascular events. The primary endpoint was recurrence of any symptomatic atrial arrhythmia >30sec. In case of arrhythmia recurrence, ECG-documentation was pursued and evaluated. 

 

Results:  All pulmonary veins (PVs) in this cohort (157/157) were successfully isolated, in 73.2% by a single RF-application. Median procedure time was 62.5 min (Q1=50.0 min; Q3=70.5 min). No serious procedure-related complications were observed, apart from one case of unclear, post-procedural acute-on-chronic kidney injury. RF-application was prematurely terminated at 13 PVs (8.3%) due to temperature rise in the oesophageal probe. At 4 PVs (2.5%), only segmental ablation was performed due to phrenic capture at safety pacing via the balloon catheter. In 9 PVs (5.7%), acute reconnection was observed and re-ablation performed during the index procedure.

Follow-up was available in 34 patients. Sixteen patients (47%) experienced arrhythmia recurrence. Five patients (15%) underwent repeat ablation during the follow-up period. In two patients, persistent PVI was confirmed and additional substrate modification was performed. In three patients, PV-reconnection was shown and PV-re-isolation was successfully established. In one of these patients only segmental ablation had been performed at the septal PVs during the index procedure due to phrenic capture at safety pacing via the balloon electrodes. In the other patient, ablation of the respective PV had been terminated prematurely due to temperature rise in the esophageal probe.

 

Conclusion: PVI with the multielectrode RF-balloon is feasible with high procedural efficacy and safety. Arrhythmia recurrence in this unselected real-world patient cohort was high and may be influenced by higher rates of persistent AF, adverse LA remodeling and more co-morbidities in comparison to previous published cohorts. Additionally, technical limitations in the index procedure (e.g. proximity to the phrenic nerve, esophageal temperature rise) may have contributed to PV-reconnection. Long-term clinical outcome may additionally improve with increasing experience and technical optimization, and should be the subject of future larger-scale studies.