Vnitr Lek 2026, 72(1):43-46 | DOI: 10.36290/vnl.2026.006

Surprising finding of a large intracardial mass in the right atrium during catheter ablation of atrial fibrillation

Katarína Doležalová^{1, 2, 3}, Filip Souček^{1, 2, 3}, Vojtěch Šebetovský^{1, 3}, Zdeněk Stárek^{1, 2, 3}

¹ I. interní kardioangiologická klinika, Fakultní nemocnice u sv. Anny v Brně

² International Clinical Research Center, Fakultní nemocnice u sv. Anny v Brně

³ I. interní kardioangiologická klinika, Lékařská fakulta, Masarykova univerzita, Brno

Myxomas are the most common primary cardiac tumors, most often located in the left atrium. Right atrial myxomas are rare and often remain asymptomatic for a long time, which complicates early diagnosis.  Our case report describes a 53year-old male endurance athlete diagnosed with paroxyzmal atrial fibrillation, who was referred for catheter ablation – specifically, pulmonary vein isolation. During the planned procedure, intracardiac ultrasound revealed a large, mobile mass in the right atrium, attached by a stalk to the interatrial septum. The procedure was immediately aborted. Subsequent transesophageal echocardiography and cardiac magnetic resonance imaging confirmed the suspicion of a right atrial myxoma. The tumor was surgically removed shortly thereafter, and a concomitant surgical treatment of atrial fibrillation using the CryoMaze IV technique was performed. The postoperative course was uneventful. Subsequent histological examination described the lesion as either a markedly secondarily transformed myxoma or a benign cystic formation, which could not be definitively distinguished.

This case highlights the potential for even large right atrial myxomas to remain clinically silent, with atrial fibrillation possibly representing the only indirect symptom. It underscores the importance of multimodal cardiac imaging and highlights the role of intracardiac ultrasound during catheter ablation procedures – not only as a tool for procedural safety but also as a valuable diagnostic modality capable of detecting clinically silent anomalies with potential impact on patient management.

Keywords: intracardial mass, cardiac myxoma, intracardial cyst, mass in right atrium, intracardial ultrasound.

Accepted: February 3, 2026; Published: February 12, 2026  Show citation