Giant Left Atrial Myxoma Causing Functional Mitral Stenosis: A Minimally Invasive Approach

Cardiac myxoma is the most common primary cardiac tumor and typically arises in the left atrium. Large, mobile myxomas may prolapse through the mitral valve and produce functional mitral stenosis with secondary pulmonary hypertension. We report a 57-year-old woman with cardiovascular risk factors (hypercholesterolemia and obesity) who presented with New York Heart Association class III dyspnea and palpitations. First-line transthoracic echocardiography revealed a giant, mobile left atrial mass (4.7 x 4.8 cm) attached to the basal third of the interatrial septum, prolapsing into the left ventricle and producing a mean transmitral gradient of 16 mmHg with severe pulmonary hypertension (estimated pulmonary artery systolic pressure approximately 80 mmHg). Preoperative coronary computed tomography (CT) angiography, performed to exclude significant coronary artery disease given her cardiovascular risk factors and to characterize the intracardiac mass non-invasively, confirmed the mass and showed coronary atheromatosis without significant stenosis. The mass was surgically resected within two weeks of diagnosis via a minimally invasive thoracoscopic approach, decided in a multidisciplinary heart team meeting, with femoro-femoral cannulation, without preoperative anticoagulation; activity restriction and close clinical monitoring were maintained while awaiting surgery. The postoperative course was uncomplicated, with early extubation and rapid mobilization. At one-month follow-up, the transmitral gradient and pulmonary artery pressures had normalized, with a stable, mild residual mitral regurgitation and complete symptom resolution. Histopathological examination showed a well-circumscribed, non-encapsulated, smooth-surfaced proliferation of spindle-to-stellate cells within an abundant myxoid stroma, without atypia, mitoses, or necrosis; immunohistochemistry was positive for calretinin, confirming the diagnosis of myxoma. This case illustrates the diagnostic and hemodynamic impact of a giant left atrial myxoma and the feasibility of a minimally invasive thoracoscopic resection in a carefully selected patient.