Isoproterenol for Unmasking Dormant Conduction and Non-Pulmonary Vein Triggers During Atrial Fibrillation Ablation: Prospective Multicenter Study.

Background: Pulmonary vein (PV) reconnection and the onset of non-PV triggers are frequently the cause of atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA). The effectiveness of using isoproterenol for unmasking dormant conduction and non-PV-triggers during AF RFCA and its effect on improving procedural and clinical outcomes is still controversial.

Objective: To evaluate the effectiveness of isoproterenol for unmasking dormant conduction and non-PV triggers during RFCA for paroxysmal AF (PAF) and its effects on procedural and long-term clinical outcomes.

Methods: In this prospective multicenter cohort from the REAL-AF registry, patients who underwent RFCA for PAF with and without isoproterenol administration from January 2018 to May 2023 were included. The primary efficacy outcome was freedom from all-atrial arrhythmia at 12-month follow-up. Secondary outcomes included procedural and long-term clinical outcomes, and procedure-related complications.

Results: A total of 1102 patients were included (isoproterenol = 325 vs. control = 777) (mean age 66.73 ± 10.19 years; 53.05% male). There were no differences in baseline characteristics between the groups. Dormant conduction/non-PV triggers with isoproterenol were observed in 10.2% of the patients. Isoproterenol administration was associated with increased procedural times (109 (83-137.5) vs. 96 (74-122), p = 0.002), and decreased rates of first-pass PV isolation (74.84% vs. 80.14%, p = 0.007). There were no differences in freedom from all-atrial arrhythmias (HR 0.87, 95% CI [0.61-1.24], p = 0.4) or long-term clinical outcomes at 12 months of follow-up between the groups.

Conclusion: In patients undergoing RFCA for PAF, the use of isoproterenol was associated with increased procedural times and more extensive ablation, without improved clinical outcomes at 12-month follow-up.