A Feasibility Pilot Study to Assess the Efficacy of NavX Guided Detection of Pulmonary Vein Electrograms during Atrial Fibrillation Ablation [NavX Guided Detection of Pulmonary Vein Electrograms]

Abstract

Background: Pulmonary Vein Antrum Isolation (PVAI) targeting PV triggers is an established treatment for paroxysmal Atrial Fibrillation (AF). Ablation lesions are typically delivered around the entire circumference of each individual PV. This study tested a strategy where electrical inputs to the PVs were mapped using the NavX system and selectively targeted before ablation. The objectives of the study were to evaluate: 1) Likelihood of PV isolation using this strategy, 2) Correlation between manually tagged PV potentials and Complex Fractionated Electrograms identified using the NavX CFE Mean Map in sinus rhythm and during coronary sinus pacing, 3) Long term success of this strategy. Methods: Ablation was initially guided by identification of PV antral regions activating early in sinus rhythm and during Coronary Sinus (CS) pacing, and exhibiting local fractionated electrograms, mapped using the NavX system, and a circular mapping catheter. If PV isolation could not be established using this approach, it was completed using the conventional ablation approach. For analysis each vein was divided into quadrants from 12 o’clock looking from the Left Atrium (LA) into the vein. Manually identified fractionated potentials were compared with the NavX Complex Fractionated Electrogram (CFE) Mean map acquired in sinus rhythm and during coronary sinus pacing. CFE Mean Map parameters were set to a Width of 20 ms, Refractory of 30 ms, and P-P sensitivity of 0.05 mV. Manually tagged PV potentials were used as the gold standard. AF recurrences were assessed using ambulatory monitoring at 1, 3, 6 & 12 months post ablation. Results: Twenty consecutive patients with paroxysmal AF (age 59 ± 10 y, 60% male, LA 40 ± 6 mm) were enrolled in the study. Distribution of CFE closely paralleled activation. In addition, CFE were identified on the septum in sinus rhythm in 60% of the patients and on the posterior wall during CS pacing in 35% of the patients. The sensitivity-specificity of the auto-identified CFE that predicted manually tagged fractionated potentials were 60%-68% in Sinus Rhythm (SR), and 80%-70% during CS pacing. Mapping and ablation fluoroscopy time was 30 ± 12 min with Radio Frequency (RF) time of 27 ± 10 min. Completion of PVAI required an additional 22 ± 16 min of fluoroscopy and 31 ± 28 min of RF energy delivery. Total procedure time was 209 ± 36 min. Only 13 (4%) of all PV quadrants in n = 5 (25%) patients did not have to be ablated to achieve PVAI. Three patients (15%) had AF recurrences between the first 3 months and 12 months following ablation. Two of these patients cumulatively had 7 of the 13 non-ablated quadrants in the study. Conclusions: While mapping earliest PV activation during sinus rhythm and CS stimulation is feasible, ablation guided by this approach may avoid unnecessary RF energy delivery in only a small proportion of the PV antral segments, potentially leading to higher ablation failure rates. NavX CFE mean algorithm accurately identifies areas of fractionation at PV antra during sinus rhythm and distal CS stimulation corresponding to PV potentials.