Background and Rationale:~The main target in atrial fibrillation ablation is the isolation of the pulmonary veins (PVI). 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 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. Isolation of pulmonary veins is confirmed by other methods such as bidirectional block across the ablation lesions.~New technological developments have resulted in high-density mapping, such as the Advisor HD Grid mapping catheter by Abbott. This catheter has a total of 16 electrodes configured in a 4 by 4 matrix. 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.~Research Question and Objectives:~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.~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.~Secondary endpoints are:~A per vein analysis will be performed for the presence of gaps and for the mean number of gaps.~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.~Left atrial mapping time for both the CMC-20 and the HD Grid catheter~Discrepancies in the prevalence of low voltage areas defined as a voltage <0.50 mV between the CMC-20 and HD Grid catheter in sinus rhythm.~Design:~Prospective, single arm, single center, superiority study with comparison of standard 20-pole circular mapping catheter and the new HD Grid multipolar catheter.~A minimum of 20 evaluable subjects with drug refractory, symptomatic atrial fibrillation scheduled for first PVI ablation will be enrolled over a period of 12 months.~Data collection:~Demographic, clinical and AF-related information will be collected prior to the procedure. Procedure related information will be collected directly after the procedure. All data will be collected in RedCap.~Procedure:~First, a standard PVI procedure is performed. After completion of the ablation lesions, isolation of the pulmonary veins will be confirmed using the standard CMC-20 catheter. If isolation is confirmed, the CMC-20 catheter will be exchanged for the HD Grid catheter. Using the HD Grid catheter, a new map of the left atrium will be made using the high-density settings. Together with the left atrium, the pulmonary veins will be mapped again in search of electro-anatomical gaps. Gaps are defined as a local area from the ablation line reaching inwards the pulmonary vein which still shows activation or fractionated potentials in line with atrial activation whilst pacing remote in the left atrium. The prevalence and location of these gaps will be collected using the map. If gaps have been found, HD Grid guided additional ablation must be performed to achieve isolation in that vein.
The primary study concept is to evaluate the superiority of the HD Grid high-density mapping catheter over the current standard 20-pole circular mapping catheter in pulmonary vein isolation (PVI) in atrial fibrillation. A minimum of 20 evaluable subjects with symptomatic atrial fibrillation scheduled for a clinically indicated first PVI ablation will be included.