Implementation of CLOSE protocol for pulmonary vein isolation in paroxysmal atrial fibrillation by young electrophysiologists in real world clinical practice

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Paroxysmal atrial fibrillation (AF) is widely treated by radiofrequency (RF) catheter ablation. The CLOSE protocol has been proposed and accepted to guide a successful, safe and durable pulmonary vein isolation in patients with paroxysmal AF. However, the reproducibility of the protocol in real clinical practice and on less experienced hands is less established. OBJECTIVE: To assess the acute effectiveness, safety and reproducibility of RF catheter ablation based on the CLOSE protocol for pulmonary vein isolation in paroxysmal AF patients, performed by young electrophysiologists with less than 5 years of experience. METHODS: Fifty consecutive patients (25 men, aged 61±11 years) with symptomatic paroxysmal AF were enrolled during the period 2020- 2021. RF catheter ablation based on the CLOSE protocol, using a conventional contact force sensing catheter (Thermocool SmartTouch ST D/F) and a circumferential multipolar catheter (Lasso) after double transseptal puncture (2 SL0 long sheaths), under general anesthesia and oesophageal temperature monitoring was performed in all patients. RESULTS: Pulmonary vein isolation demonstrated by entrance and exit block was achieved in all patients. Total procedure time was 147 ± 29 minutes, exposure X-ray time was 5.36 ± 4.46 minutes and exposure dose was 922 ± 1616 cGy*cm2. Left pulmonary veins (LPVs) first pass isolation (94%) was numerically higher than the right pulmonary veins (RPVs) first pass isolation (82%). There were not safety issues. In comparison with the results reported by the authors of the CLOSE protocol, the procedure time was similar (p= 0.84), however, the exposure X-ray time and the exposure dose were significantly lower in our study (p<0.0001 and p=0.01, respectively). The rates of first pass isolation of left and right pulmonary veins did not differ when compared to the respective rates reported by the CLOSE protocol authors (82% vs CLOSE 100% for RPVs and 94% vs CLOSE 97% for LPVs, p> 0.05 for both). CONCLUSIONS: RF catheter ablation in paroxysmal AF patients using the CLOSE protocol is highly effective, safe and reproducible not only by experienced but also by young electrophysiologists. Adaptation of an ablation strategy for pulmonary vein isolation based on the CLOSE protocol may improve the workflow of the procedure and the training curve of young electrophysiologists without compromising the efficacy and safety.