Aims: Real Time Recordings (RTR) of pulmonary vein (PV) provide important information in the setting of the 2nd generation Cryoballoon (CB-A), as a funcion of time to isolation. Visualization of RTR with the standard inner lumen mapping catheter (ILMC) 20mm Achieve (AC) is possible in roughly 50% of PVs. A novel 25mm-Achieve Advance (AC-A) has been developed with the aim of increasing the detection of RTR. The purpose of this study is to compare the AC-A with the AC, to feasibility and improvement of RTR. Methods: We assigned 50 patients with paroxysmal or persistent atrial fibrillation to CB-A PVI, using the AC-A as ILMC. We compared this group with 50 patients, matched for age and left atrial volume, who previously underwent the CB-A PVI using the AC. Results: RTR were more frequently observed with the AC-A than with the AC (74% vs 49%; p= 0.02). RTR detection in the left superior PVs was similar in both groups (74% vs 72%, p= 0.8). RTR with the AC-A were equally appreciated in left or right sided, superior or inferior PVs. No significant differences were found in terms of feasibility, procedure fluoroscopy and freezing times, nadir temperatures, and acute PVI. Conclusion: CB-A PVI with the AC-A is feasible and safe in all PVs. The AC-A has proven significantly superior in visualising RTR if compared to the AC, affording RTR in 74% of PVs.