Effective ablation settings that predict chronic scar after atrial ablation with HELIOSTAR™ multi-electrode radiofrequency balloon catheter

Background: Radiofrequency balloon (RFB) ablation (HELIOSTAR™, Biosense Webster) has been developed to improve pulmonary vein ablation efficiency over traditional point-by-point RF ablation approaches. We aimed to find effective parameters for RFB ablation that result in chronic scar verified by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR).

Methods: A chronic canine model (n = 8) was used to ablate in the superior vena cava (SVC), the right superior and the left inferior pulmonary vein (RSPV and LIPV), and the left atrial appendage (LAA) with a circumferential ablation approach (RF energy was delivered to all electrodes simultaneously) for 20 s or 60 s. The electroanatomical map with the ablation tags was projected onto the 3-month post-ablation LGE-CMR. Tags were divided into two groups depending on whether they correlated with CMR-based scar (ScarTags) or non-scar tissue (Non-ScarTags). The effective parameters for scar formation were estimated by multivariate logistic regression.

Results: This study assessed 80 lesions in the SVC, 80 lesions in the RSPV, 20 lesions in the LIPV, and 30 lesions in the LAA (168 ScarTags and 42 Non-ScarTags). In the multivariate analysis, two variables were associated with chronic scar formation: temperature of electrode before energy application (odds ratio (OR) 0.805, p = 0.0075) and long RF duration (OR 2.360, p = 0.0218), whereas impedance drop was not associated (OR 0.986, p = 0.373).

Conclusion: Lower temperature of the electrode before ablation and long ablation duration are critical parameters for durable atrial scar formation with RFB ablation.