Background: 
Right atrial appendage (RAA) tachycardiais more prevalent in young male patients and is associated with tachycardia-induced cardiomyopathy. Medical failure for focal right atrialappendage (RAA) tachycardia is common, and interventional treatment remains a great challenge. Over the past two decades, efforts have been made to develop a better understanding of the characteristics of these tachycardias. Three-dimensional activation mapping facilitates precise identification of the origin of the tachycardia, but catheter ablation is still associated with high recurrence rates. In particular, RAA tachycardias arising from the distal RAA often require open surgical intervention with excision of the RAA. No data are available regarding the use of pulsed field ablation for RAA tachycardias. 

Case summary: 
A 21-year-old male patient was transferred to our department from another hospital. He presented to the external emergency department due to exertional dyspnea and palpitation with increasing symptoms for 10 days. Transthoracic echocardiography assessed an ejection fraction of 28%, and a left ventricular end-diastolic diameter of 73mm. Cardiac magnetic resonance imaging was not indicative of myocarditis or other myocardial injuries. The 12-lead electrocardiogram showed repetitive runs of narrow complex tachycardia with 1:1 A-V conduction suggestive of focal atrial tachycardia arising from the RAA (Figure 1). The suspected diagnosis was an arrhythmia-induced cardiomyopathy, and rhythm-control was aspired. During the electrophysiology study, earliest atrial activation of spontaneous runs of the clinical tachycardia was found at the distal end of the RAA. RAA angiography was performed (Figure 2), and biphasic pulsed field ablation (PFA) was applied inside of the RAA with a generator output of 2,000 V per application. A total of six PFA applications were applied, and the patient already remained in stable sinus rhythm after the first application. Post-ablation voltage mapping demonstrated electrical isolation of the RAA (Figure 3). A follow-up with assessment of the left ventricular ejection fraction is scheduled six weeks after discharge from our hospital. 

Discussion: 
The present case report is the first to report the use of PFA for the treatment of RAA tachycardia. PFA appears to be highly effective and might improve clinical outcomes of catheter ablation of these challenging arrhythmia; in particular, the need for open surgical intervention might be overcome. More data are warranted to confirm these findings.