Three dimensional ultra-high density electro-anatomical mapping and transcatheter radio-frequency ablation for diagnosis and treatment of sustained atrial tachycardia in eight horses

Background: Atrial tachycardia (AT) in horses is currently treated by medical or electrical cardioversion, but the recurrence rate is high. The development of 3D electro-anatomical mapping allows a more accurate diagnosis and possible treatment by ablation, which may provide a permanent solution. Objectives: To describe the 3D electro-anatomical findings in horses with persistent AT and preliminary results of treatment by transcatheter radiofrequency ablation. Study design: Case series Methods: Records from eight horses with sustained AT treated by radiofrequency ablation at Ghent University were reviewed. Results: Eight horses with persistent AT were treated by ablation which resulted in immediate restoration of sinus rhythm in seven out of eight horses. In the successfully treated horses the origin of the AT was located in the caudal right atrium, at the transition between the right atrium and caudal vena cava. The underlying mechanism was a local reentry circuit in 4 horses and focal AT in 3 horses. Three of the successfully ablated cases showed recurrence of AT at 6, 7 and 8 months after the initial ablation procedure. One horse had recurrence twice and had two subsequent mapping procedures followed by successful ablation. Main limitations: Small number of patients. Conclusions: The underlying mechanism of AT and the precise anatomical location can be identified by 3D electro-anatomical mapping. Radiofrequency ablation was feasible and effective to treat persistent AT in adult horses.