Rare Left‐Sided Accessory Pathway Successfully Ablated with Atrial Insertion Site at the Left‐side Fossa Ovalis

Introduction: Left-sided accessory pathway (AP) with atrial insertion away from the annulus is an atypical variation. Conventional mapping and ablation performed along mitral annulus (MA) is usually ineffective.Methods: A 14-year-old girl without structural heart disease presented with recurrent episodes of sudden onset palpitations and electrocardiogram (ECG) showed a narrow QRS complex tachycardia.Results: Electrophysiology study (EPS) was done and anterograde atrioventricular reentrant tachycardia (AVRT) with AP was diagnosed. Conventional mapping and ablation performed along TA and MA was failed. 3D-activation mapping found the retrograde atrial insertion site of AP on the left atrium fossa ovalis (FO), and AP was successfully abolished by radiofrequency ablation at that site.Conclusion: As reported, this patient is the first report of ablating a left-sided AP with retrograde atrial insertion on the left atrium FO.