Ultra-high density mapping for the evaluation of the antral scar extension after ablation with a radiofrequency balloon catheter in atrial fibrillation patients

Abstract Background The Heliostar radiofrequency (RF) balloon ablation catheter enables one-shot pulmonary veins isolation (PVI). The RF balloon by occluding the PV ostia creates an antral scar. Purpose We sought to investigate the extension of the antral scar by mean of ultra-high density mapping. Methods Paroxysmal and persistent atrial fibrillation (AF) patients undergoing first PVI ablation with the Heliostar catheter across 4 European centers were enrolled. Ultra-high density mapping of left atrium was performed with the Octaray catheter, a octa-spline mapping catheter before and after the ablation. All maps were acquired in sinus rhythm, patients in AF underwent electrical cardioversion before mapping. The bipolar voltage maps from each patients were analysed: the left atrial area < 0.2 mV was considered scar and was calculated before and after the ablation and the distance between left and right antral lesions at upper and inferior posterior wall were also calculated. Results Overall, 49 patients were enrolled, 82% were male, the mean age was 60±9 years, 66% had paroxysmal AF. PVI was achieved in 100% patients. The mean left atrial area was 209±44 cm2, the scar after the ablation was 9±4.6 %, with 49±11% of the posterior wall still viable (bipolar voltage > 0.5mV). The distance between left and right antral lesions at the upper posterior wall was 26.57 mm whereas at the inferior aspect was 29.59 mm. Conclusions The RF balloon catheter creates a wide antral scar during AF ablation although without compromising the integrity of the posterior wall.