Giant left atrial myxoma presenting as malignant heart failure and rapid atrial fibrillation in a young adult: a case report

Primary cardiac tumours are rare, with cardiac myxomas representing the most common benign subtype in adults. Despite their benign histology, atrial myxomas may lead to significant clinical manifestations, including arrhythmias and heart failure. Giant left atrial myxomas are particularly uncommon, and their clinical presentation may vary depending on size, location, and associated haemodynamic effects.

A 37-year-old man presented with atrial fibrillation with rapid ventricular response, elevated NT-proBNP, cardiomegaly, and pleural effusion. Transthoracic and transoesophageal echocardiography demonstrated a massively dilated left atrium nearly occupied by a large intracavitary mass, accompanied by severe left ventricular systolic dysfunction (LVEF 15%–20%). Computed tomography identified a heterogeneous left atrial mass consistent with atrial myxoma. No Doppler evidence of significant mitral inflow obstruction was identified. The patient underwent surgical resection, and histopathology confirmed atrial myxoma. At 6-week follow-up, the patient demonstrated marked symptomatic improvement with recovery of left ventricular systolic function (LVEF 45%–50%).

This case illustrates an uncommon presentation of a giant left atrial myxoma associated with atrial fibrillation and severe but reversible left ventricular dysfunction. The clinical course is consistent with tachycardia-induced cardiomyopathy rather than a purely obstructive mechanism. This case highlights the importance of recognizing arrhythmia-mediated ventricular dysfunction in patients with intracardiac masses, as well as the role of multimodality imaging and timely surgical intervention.