BACKGROUND Interventional therapy of atrial fibrillation (AF) is often associated with long examination and fluoroscopy times. The use of mapping catheters in addition to the ablation catheter requires multiple transseptal sheaths for left atrial access. OBJECTIVES The purpose of this prospective study was to evaluate feasibility and safety of pulmonary vein (PV) isolation using the high-density mesh ablator (HDMA), a novel single, expandable electrode catheter for both mapping and radiofrequency (RF) delivery at the left atrium/PV junctions. METHODS Twenty-six patients with highly symptomatic paroxysmal AF (14, 53.8%) and persistent AF (12, 46.2%) were studied. Segmental PV isolation via the HDMA was performed using a customized pulsed RF energy delivery program (target temperature 55-60 degrees C, power 70-100 W, 600-900 seconds RF application time/PV). RESULTS All 104 PVs in 26 patients could be ablated by the HDMA. Segmental PV isolation was achieved with a mean of 3.25 +/- 1.4 RF applications for a mean of 603 +/- 185 seconds. Entrance conduction block was obtained in 94.2% of all PV. The mean total procedure and fluoroscopy time was 159.0 +/- 32 minutes and 33.5 +/- 8.6 minutes, respectively. None of the patients experienced severe acute complications. After 3 months no PV stenosis was observed, and 85.6% and 41.6% of the patients with PAF and persistent AF, respectively, did not report symptomatic AF. CONCLUSIONS In this first study of PV isolation using the HDMA, our findings suggest that this method is safe and yields good primary success rates. The HDMA simplifies AF ablation, favorably impacting procedure and fluoroscopy times.