CASE PRESENTATION: An 87 year old Chinese lady presented to us with acute shortness of breath while walking. She was known to have hypertension and hypothyroidism. She did not have chest pain. There were no preceding infective symptoms or symptoms of heart failure, apart from chronic leg swelling that worsened towards the evening. On auscultation, heart sounds were dual without murmurs and there were bibasal fine crepitations in the lungs. Left calf circumference was larger than right, with bilateral varicose veins and pitting edema. She initially required 3 litres of supplemental oxygen via nasal prongs, which was weaned off within hours without diuresis. A similar episode of acute breathlessness, desaturation and quick weaning of oxygen occurred again in the ward. Chest radiography showed perihilar congestion and small pleural effusions. D dimer was >4ug/mL. A computed tomography pulmonary angiogram (CTPA) was done to rule out pulmonary embolism. CTPA showed a 4.9 x2.3 cm filling defect in the left atrium extending into the left ventricle with left atrial enlargement and pulmonary vessel congestion (Fig. 1). An urgent transthoracic echocardiogram (TTE) confirmed a mobile mass in the left atrium attached to the interatrial septum that moved across the mitral valve, causing ventricular inflow obstruction (Fig. 2). Urgent cardiothoracic opinion was sought. The patient successfully underwent excision of the left atrial mass and a coronary artery bypass graft. Histology of the 5 x 3 x 1.5 cm pedunculated mass confirmed the diagnosis of cardiac myxoma.