Background/Introduction: Pulmonary vein isolation (PVI) is an established treatment option for patients with persistent atrial fibrillation (PersAF). Corresponding success rates in long-term sinus rhythm (SR) maintenance remain modest. Identifying arrhythmogenic substrate depends on the quality of the mapping catheter. Recent advancements in high-density (HD) mapping may help more accurately identify substrates and achieve successful procedural outcomes in treating PersAF.

Purpose: The Advisor™ HD Grid Mapping Catheter Observational Study (NCT03733392) was designed to quantify and characterize the utility of electroanatomical mapping with the Advisor™ HD grid mapping catheter in subjects with PersAF in the real-world environment. This study was sponsored by Abbott Laboratories.  

Methods: The novel Advisor™ HD Grid mapping catheter consists of four splines with four 1mm equidistant electrodes mounted on each spline and attached at the tip. Thus, allowing for simultaneous analysis of adjacent orthogonal bipolar signals that assist in substrate characterization.The Advisor™ HD Grid mapping catheter was used in PersAF subjects indicated for radiofrequency (RF) ablation to gather data regarding ablation strategies, mapping efficiency, procedural outcomes, as well as acute and long-term effectiveness. Subjects were enrolled from January 2019 to April 2020 across 25 sites and followed for 12 months after the procedure. 

Results: A total of 334 PersAF subjects were enrolled in this study (64.2 years; 76% male). 5.7% (19/334) of subjects reported a history of long-standing persistent AF, however, all met the inclusion/exclusion criteria for PersAF at time of enrollment. Types of maps generated include peak-to-peak voltage (78%; 322/413), local activation time (LAT) (11.4%; 47/413), and complex fractionated electrogram (CFE) mean (7.7%; 32/413). Median total mapping points collected and used were 8428.0 (IQR 4845.0-13366.0) and 2099.0 (IQR 1219.0-2947.0), respectively, in a median of 11.0 (IQR 7.3-16.0) minutes per map. Low voltage, scar/fibrosis, and CFE were searched for in 90.4% (302/334), 53.6% (179/334), and 15.9% (53/334) of subjects, respectively. A PVI approach was used in 93.7% of all ablation procedures and the strategy was limited to only PVI in 57.8% (193/334) subjects. Other ablation strategies used include targeting left atrial roof (19.8%; 66/334), posterior wall isolation (12.3%; 41/334), CFE (7.5%; 25/334) and isolation of fibrotic areas (4.8%; 16/334). HD mapping identified signals of interest that were not identified with the ablation catheter in 80.4% (205/255) subjects. The total procedure time was 134.3 ± 51.3 minutes with a fluoroscopy time of 14.5 ± 11.3 minutes. Of the subjects in AF during the procedure (59.6%; 199/334), AF was terminated in 80.4% (160/199) of subjects. Freedom from arrhythmia recurrence at 12-month follow-up was 87.4% (173/198). A total of 13.8% (46/334) of PersAF subjects experienced an adverse event (AE) of any type including one death unrelated to the procedure. Only one AE was reported to be a serious event (stroke).

Conclusions: Overall, this study provides insights supporting the use of the Advisor™ HD Grid mapping catheter to create detailed electroanatomical maps and electrogram signal quality which guided ablation strategies to treat PersAF. The results of this study support the safety and utility of HD Grid mapping catheter in subjects with complex arrythmias in the real-world setting.