Ablation at interatrial connections in biatrial flutter following anteroseptal mitral isthmus line: a case series

Left atrial perimitral flutter is a common late complication of atrial fibrillation ablation. Repeat ablation with a posterolateral mitral isthmus line to eliminate the flutter circuit has proven technically challenging, leading some to opt for anteroseptal line ablation as an alternative. A significant issue with the latter approach is the emergence of a biatrial flutter using the right atrial septum via epicardial connections to bypass the line of block and allow continued flutter propagation. In this case series we present our experience of biatrial flutter in patients with previous anteroseptal left atrial ablation, and discuss the diagnosis and management of this arrhythmia.

We reviewed all cases of biatrial flutter treated at our institution from January 2017 to July 2024. Details of electro-anatomical mapping, ablation strategies and follow-up are described. Four cases of biatrial flutter were identified. All patients were male and had undergone prior pulmonary vein isolation and anteroseptal line. Ablation at sites of interatrial conduction successfully terminated biatrial flutter in 3 out of 4 cases. The remaining case had an unsuccessful ablation and was cardioverted to sinus rhythm. All cases remained free of recurrent atrial arrhythmia at most recent follow-up.

Biatrial flutter is a potential complication following anteroseptal line formation for perimitral flutter, necessitating biatrial mapping for diagnosis. Ablation at interatrial connection sites where earliest activation is identified is a potentially effective treatment strategy.