# Radiofrequency Ablation for Focal Atrial Tachycardia Originating From the Fossa Ovalis: Experiences and Outcomes

## TL;DR

This study shows that bilateral radiofrequency ablation is more effective than unilateral ablation for treating focal atrial tachycardia originating from the fossa ovalis.

## Contribution

The study introduces bilateral ablation as a superior strategy for treating focal atrial tachycardia from the fossa ovalis, based on electrocardiographic and anatomical findings.

## Key findings

- Bilateral ablation eliminated recurrence in focal atrial tachycardia patients, while unilateral ablation had a 16.6% recurrence rate.
- FAT originating from the fossa ovalis was found in 3.5% of atrial tachycardia patients.
- Bi-atrial mapping is necessary for successful ablation of FAT from the fossa ovalis.

## Abstract

This study aimed to investigate the electrocardiographic characteristics, electrophysiological features, and outcomes of radiofrequency ablation in patients with focal atrial tachycardia (FAT) originating from the fossa ovalis (FO).

We retrospectively analyzed 67 patients with FAT originating from the FO and classified into two groups: the Unilateral Ablation Group (n = 36) and the Bilateral Ablation Group (n = 31). Patients in the Unilateral Ablation Group underwent ablation on the earliest single side, whereas patients in the Bilateral Ablation Group underwent ablation on both the right and left earliest sides. Ablation targets were guided by fluoroscopy, three‐dimensional mapping, and intracardiac ultrasound. All patients were followed up for more than 1 year.

Out of 1914 patients with atrial tachycardia, 3.5% had FAT originating from the FO. Fifty‐four patients were located at the superior area of the FO with positive P waves in inferior leads, while 13 patients were located at the inferior area of the FO with negative P waves in inferior leads. The recurrence rate of FAT was 16.6% in the Unilateral Ablation Group, but no recurrence occurred in the Bilateral Ablation Group during regular follow‐up (p = 0.026). Among the six patients with recurrence, five underwent left‐sided ablation and one underwent right‐sided ablation. All recurrent cases were then ablated by a bilateral strategy. Follow‐up showed no further recurrence.

Bi‐atrial mapping is necessary for ablation of FAT arising from the FO. Bilateral ablation for FO AT appears to be more reasonable.

This graphical summary illustrates the electrocardiographic and anatomical features of focal atrial tachycardia (FAT) originating from the fossa ovalis (FO), along with ablation strategies and outcomes. Panel A shows distinct P wave patterns on surface ECG that help differentiate superior from inferior FO origins. Panel B depicts the anatomical distribution of FAT sites in the FO region and highlights the study's classification into superior (n = 54) and inferior (n = 13) areas. Panel C presents an anatomical view of the FO within the atrial septum. The study demonstrates that bilateral ablation, guided by bi‐atrial mapping, significantly reduces recurrence compared to unilateral ablation in patients with FO‐FAT.