Three-dimensional electro-anatomical mapping of premature atrial complexes originating from the right atrial free wall and treatment by radiofrequency ablation in three horses.

Background: Frequent premature atrial complexes (PACs) can increase the risk of atrial fibrillation or atrial tachycardia, and pharmacological therapy can be challenging.

Objective: To report the use of three-dimensional electro-anatomical mapping of PAC originating from the right atrial free wall and treatment by radiofrequency ablation in three horses.

Study design: Retrospective case report.

Case description: Frequent premature atrial complexes (PACs) were diagnosed in three horses. Twelve-lead ECG and vectorcardiography suggested an origin in the right lateral free wall in two horses and the caudal right atrium in one horse. Three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency ablation using the CARTO™ 3 system were performed. Isoprenaline or dobutamine administration allowed activating the focus of PACs during general anaesthesia. Activation mapping using Pattern Matching Filtering identified the origin of PACs at the mid portion of the right atrial free wall in all horses. In the first horse, ablation was not performed due to pacing-induced phrenic nerve stimulation at the site of earliest activation. In the second horse, PACs disappeared after the 18th energy application and were no longer inducible by dobutamine. In the last horse, ablation was not successful in eliminating PACs.

Main limitation: Small number of cases.

Conclusion: The 3D EAM identified the focus of PACs at the right atrial free wall in three horses, revealing it as a possible arrhythmogenic area. Although still challenging, radiofrequency ablation has promise as a treatment to provide a permanent solution for frequent PACs.