Giant Left Atrial Myxoma Causing Dynamic Mitral Inflow Obstruction

BACKGROUND: Atrial myxomas are the most common primary cardiac tumors. Larger tumors (>5 cm) are associated with increased risk of obstruction and hemodynamic compromise, while very large ("giant") myxomas are rare. CASE SUMMARY: A 34-year-old man with atrial fibrillation was found to have a large left atrial mass after presenting with tachyarrhythmia. Echocardiography demonstrated an ovoid mass prolapsing through the mitral valve, producing functional mitral stenosis (mean gradient 8 mm Hg), marked atrial dilation, and reduced ejection fraction (30%). Surgical resection revealed a near-spherical tumor measuring 8.2 × 5.5 × 5.5 cm attached to the interatrial septum. Left ventricular function improved to 45% after 7 days postop. DISCUSSION: Giant atrial myxomas can cause severe hemodynamic compromise through mechanical obstruction, with tumor size and morphology playing key roles. TAKE-HOME MESSAGE: Obstructive physiology from atrial myxomas can be reversible, highlighting the importance of early recognition and surgical intervention.