P887 Two sides of the same mass

Abstract Echocardiography (echo) remains the first-line imaging modality for the evaluation of cardiac masses. Three-dimensional (3D) echo, either transthoracic or transesophageal (TTE and TEE respectively), has allowed for better definition imaging, providing more information about the size, mobility, attachment and relation of these lesions with cardiac structures. Nevertheless, due to its superior tissue characterization capability, other imaging techniques, such as cardiac magnetic resonance (CMR), are very helpful in the differential diagnosis, making multimodality imaging the most attractive option for the study of intracardiac masses. We present the case of a 85 year-old male, with paroxysmal atrial fibrillation (under effective anticoagulation), type 2 diabetes mellitus, hypertension, referred for the study of an asymptomatic cardiac mass found in a routine TTE. There were no relevant findings on physical examination. The TTE showed a bilobar spheroid mass, in the right atrium, attached to the interatrial septum, with 33x23mm and regular edges. A 3D TEE was performed confirming the previous findings, but also showing extension of this mass through the fossa ovalis membrane, reaching the left atrium; this aspect raised the doubt about either protrusion or invasion of the left atrium and, respectively, a benign (like a myxoma) versus malignant behaviour (such as a sarcoma). To better characterize this lesion, a CMR was ordered, which revealed a bilobar heterogeneous mass, attached to the right side of the interatrial septum, at the fossa ovalis membrane, without signs of adjacent tissue invasion, namely unequivocal invasion of the left atrium; it presented with intermediate T1 signal, hyperintense T2 signal and heterogeneous pattern of gadolinium enhancement, features mostly in favour of a right atrial myxoma. The complimentary study found no other relevant changes, namely no findings suggestive of endocarditis (negative blood cultures), autoimmune disease or malignancy. The patient refused undergoing heart surgery and, therefore, kept follow-up with clinical and echocardiographic stability. Although histological examination remains the only tool for definitive diagnosis, multimodality imaging allows a quite comprehensive evaluation of intracardiac masses, enlightening the differential diagnosis. Here the imaging findings helped to establish a benign origin as the most likely, very important in this case of a probable right atrial myxoma, due to its peculiar protrusion to the left atrium through the fossa ovalis membrane. Abstract P887 Figure. atrial myxoma