Radiofrequency pulmonary vein isolation using catheter dragging technique guided by grid annotation vs. point-by-point technique guided by Ablation Index: a randomized controlled trial
Authors: Mulder M.J , Kemme M.J.B , Hopman L.H.G.A , Hagen A.M.D , Van De Ven P.M , Hauer H.A , Tahapary G.J.M , Van Rossum A.C , Allaart C.P 
Published: October 2021

Abstract

Background
Pulmonary vein isolation (PVI) with radiofrequency (RF) ablation is an important treatment option in symptomatic atrial fibrillation (AF) patients. Ablation Index (AI) has recently attracted considerable interest as a guide for PVI procedures and combines contact force, RF application time and ablation power into a single metric. A limitation of ablation strategies guided by AI is the impossibility to use a catheter dragging technique. Although comparative studies are sparse, ablation using a catheter dragging technique may shorten procedural duration and improve PVI durability by creating uninterrupted linear ablation lesions. These ablation lesions can be visualized by a grid (grid annotation), which may provide valuable information on both lesion depth and lesion contiguity. We compared an AF ablation approach guided by grid annotation, with a point-by-point AI annotation approach in a single-center randomized study.

Methods
Eighty-eight patients with paroxysmal or persistent AF were randomized 1:1 to undergo RF-PVI guided by either grid annotation or AI annotation. In the grid annotation arm, ablation was visualized using automatic generation of 1mm3 grid points projected on the electroanatomic map, with grid points coloring red after 15 seconds of ablation while meeting predefined stability and contact force criteria. Ablation was performed aiming for a continuous circle of red grid points. In the AI annotation arm, ablation was visualized using automatically generated lesion tags with a diameter of 3 mm. AI target values were set at 380 and 500 for posterior/inferior and anterior/roof segments, respectively. Ablation lesions were created in a point-by-point fashion, aiming for a maximum interlesion distance of 6 mm. All study participants were followed up for 12 months after PVI using out-patient clinic visits, ECGs, 24-hour Holter monitoring and a mobile-based one-lead ECG device to assess heart rhythm when symptoms suggestive of an arrhythmia occurred.

Results
The primary endpoint of procedure time was not different between the two randomization arms (grid annotation 71±19 min, AI annotation 72±26 min, p=0.765, Figure 1A). RF time was significantly longer in the grid annotation arm compared with the AI annotation arm (49±8 min vs. 37±8 min, respectively, p&lt;0.001). Neither fluoroscopy time or radiation dose were different between the randomization arms. All patients completed 12 months of follow-up and recurrent atrial tachyarrhythmias were observed in 29 patients (33%). Recurrence of any atrial tachyarrhythmia was documented in 10 patients (23%) in the grid annotation arm compared with 19 patients (42%) in the AI annotation arm, which did not reach statistical significance by log-rank test (p=0.074, Figure 1B).

Conclusions
Findings from this randomized controlled study suggest that grid annotation may provide an alternative approach for RF-PVI using AI, allowing for ablation with the catheter dragging technique.

Funding Acknowledgement
Type of funding sources: Private company. Main funding source(s): Biosense Webster, Inc. Figure 1