Background: During catheter ablation of atrial fibrillation (AF), placing contiguous point ablation lesions to electrically-isolate the pulmonary veins (PV) can be technically challenging. A novel balloon catheter (Endoscopic Ablation System - EAS; Cardiofocus, Inc.) which utilizes a miniatuře endoscope for real-time visualization during ablation has been developed. This systém employs arcs of light-energy that are adjustable (rotating, advancing, retracting) independent of the balloon to direct energy to the pulmonary veins PV-left atrium(LA) region. This report details the first clinical long-term follow-up results from a prospective multcentric trial in patients from our center. Methods: 22 patients with a history of symptomatic drug-resistant paroxysmal AF were studied: Sex: M/F = 19/3; Age 53 ± 8 years (29-73); AF duration: 7.0 ± 3.0 years (1-14); LA diameter: 42 ± 4 mm (33-49); left ventricular ejection fraction (LVEF) 68 ± 4% (45-77). A single treatment consisting of isolation of the PV ostia was delivered using the EAS. There were no exclusion criteria related to morphology/number of PVs Results: During long-term follow-up 17.1 ± 6.6 months (7-27) AF free endpoint was achieved in 19 (86.3%) patients, of whom 7 (33 %) patients needed adjunctive betablocker and/or propafenon. Three patients (13.6 %) experienced AF despite antiarrhythmic therapy, the proceduře was successfully repeated in one patient. During 6 to 12 moths follow-up visits, a computed tomography revealed only mild stenosis 26.4 ± 4,4 % (20-37) in 16 % of PVs. Two adverse events were documented: transient ischemic attack, and pseudoaneurysm of a right femoral artery solved by a percutaneous glue-tissue application. The time of proceduře + fluoroscopy significantly decreased during a learning curve. Conclusion: This initial clinical-feasibility study suggests that a single treatment with the EAS of paroxysmal AF appears safe and efficacious. Key

        Key words: paroxysmal atrial fibrillation, catheter ablation, transseptal puncture, pulmonary vein isolation, light-energy laser are.