A 32-year-old female presented with a 6-month history of worsening non-productive chronic cough and palpitations on moderate exercise. Chest X‑ray showed an increased cardiothoracic ratio with a prominent left heart border. She underwent transthoracic echocardiography in which a large cystic structure with compressive effect on the left ventricle was identified (Fig. 1a). Further evaluation by transoesophageal echocardiography proved the structure to be a large left atrial appendage aneurysm (LAAA) (7.7 × 4.4 cm) with a 1 cm entrance to the atrial cavity (Fig. 1b). The patient underwent aneurysm resection under cardiopulmonary bypass. Fig. 1c shows the resected aneurysm, which had a very thin wall. The postoperative course was uneventful.