Discrepancies in the prevalence of low voltage areas defined as a voltage Left atrial mapping time for both the CMC-20 and the HD Grid catheter.A per pair of veins (left and right separately) analysis will be performed for the presence of gaps and for the mean number of gaps.A per vein analysis will be performed for the presence of gaps and for the mean number of gaps.The primary endpoint is the mean number of gaps identified per patient, and their location identified by the HD Grid catheter after standard PVI procedure with the CMC-20 catheter. The primary objective of this study is to demonstrate the superiority of the HD Grid catheter when compared to the CMC-20 catheter in atrial fibrillation ablation. With each electrical wavefront being decomposed to 2 orthogonal vectors, every direction of a local wavefront should be detected by these configurations and thus overcoming the bipolar blindness. This catheter has a total of 16 electrodes configured in a 4 by 4 matrix. New technological developments have resulted in high-density mapping, such as the Advisor HD Grid mapping catheter by Abbott. Isolation of pulmonary veins is confirmed by other methods such as bidirectional block across the ablation lesions. The current standard of mapping the pulmonary vein ostia during PVI ablation is a 20-pole circumferential catheter (CMC-20) which collects anatomical and electrical information by moving it in the left atrium and making contact with the atrial wall. This is performed by point-by-point ablation with radiofrequency energy creating 2 circles, one around the left superior and inferior pulmonary vein and one around the right superior and inferior pulmonary vein. The main target in atrial fibrillation ablation is the isolation of the pulmonary veins (PVI). Why Should I Register and Submit Results?.