Congestive heart failure as the presenting form of a giant left atrial appendage aneurysm: a case report.

Background: Left atrial appendage aneurysm (LAAA) is an exceptionally rare cardiac abnormality that may be congenital or acquired. Although many patients remain asymptomatic for years, common presentations include palpitations, dyspnoea, and thromboembolic events. Case summary: A 30-year-old woman with no medical history presented with 2 weeks of palpitations and exertional dyspnoea. Examination revealed mild congestion and an irregular rhythm. Electrocardiography showed atrial fibrillation with a slightly rapid ventricular response. Chest radiography demonstrated a prominent left mediastinal border. Transthoracic echocardiography identified a large congenital LAAA adjacent to a normal-sized left ventricle with moderately reduced ejection fraction. She improved with intravenous diuretics, anticoagulation, and guideline-directed medical therapy. Given her preference for conservative therapy, she was discharged on rivaroxaban. She remained asymptomatic during follow-up. Discussion: LAAA should be suspected in patients with unexplained left-sided mediastinal enlargement and atypical echocardiographic findings. Imaging is essential for diagnosis, and surgical aneurysmectomy is considered curative, although evidence guiding management in asymptomatic individuals is limited. Selected patients may be managed conservatively with close follow-up.