Background: Previous studies demonstrated that the coronary sinus (CS) is important as a target for ablation in persistent atrial fibrillation (AF), atrial tachycardias, and atypical atrial flutters. CS ablation is associated with improved ablation outcome in persistent AF after failed PVI. However, RF ablation of the CS is associated with coronary vessel damage. Animal data suggests irreversible electroporation (IRE) ablation can be a safe ablation modality in vicinity of the coronary arteries. We investigated the feasibility of IRE in the coronary sinus (CS) in a porcine model.
Objective: Determine the feasibility of performing CS ablations with IRE.
Methods: The study was performed in 6 pigs (weight 60-75kg). A modified 9F steerable hexapolar Tip-Versatile Ablation Catheter (TVAC; Medtronic Ablation Frontiers, CA, USA), containing five 2 mm long band electrodes and a 4 mm tip electrode with 3 mm spacing, was introduced in the CS. Pacing maneuvers were performed from distal to proximal in the CS to assess atrial capture thresholds before and after ablation (up to 10 mA). Ablation was performed with 100 J IRE pulses using a Lifepak 9 monophasic defibrillator. After 3-week survival animals were euthanized and histological sections from the CS were analyzed.
Results: A total of 27 IRE applications in 6 animals were performed. Mean peak voltages was 1509±36 V , with a mean peak current of 22.9±1.0 A. No complications occurred during procedure and 3-week survival. Successful ablation of muscular sleeves along the CS defined as absence of atrial capture with CS pacing was achieved in all animals. Pacing thresholds in the CS were significant higher at 3 weeks as compared to baseline (2.4 mA; interquartile range, 1.6 to 5.5; versus 10 mA; interquartile range, 4.0 to 10.0; p<0.001). Histological analysis showed transmural ablation lesions in muscular sleeves around the CS. Although the lesions were not circular, transmural lesions were created at the left atrial side of the CS.
Conclusion: IRE ablation of the musculature along the CS using a multielectrode catheter is feasible in a porcine model. The results might contribute to development of IRE ablation in treatment of CS dependent atrial tachyarrhythmias including persistent AF.