Diagnosis and Management of Left Atrial Mass with Syncope

A. Diagnosis: Left Atrial Myxoma

The diagnosis is left atrial myxoma, the most common primary cardiac tumor, accounting for approximately 50% of all benign cardiac neoplasms, according to the American Heart Association 1, 2
Myxomas occur most frequently in the left atrium, typically attached to the interatrial septum, as reported by the American College of Cardiology 1
Cardiac myxomas have an incidence of 0.02% in autopsy series, as noted by the European Society of Cardiology 1, 3

The syncope results from mechanical obstruction of blood flow across the mitral valve during diastole, causing transient reduction in cardiac output and cerebral hypoperfusion, as explained by the European Heart Journal 4, 5
This intermittent obstruction reduces left ventricular filling and cardiac output, leading to cerebral hypoperfusion and loss of consciousness, according to the American Heart Association 4
The tumor may cause reflex vagal responses leading to vasovagal-type syncope, as reported by the European Society of Cardiology 5

Myxoma cells (lepidic cells) are polygonal to stellate-shaped cells with abundant eosinophilic cytoplasm, arranged singly or in small clusters within myxoid stroma, as described by the European Society of Cardiology 3
The stromal characteristics include abundant myxoid (mucopolysaccharide-rich) extracellular matrix, loose, gelatinous appearance with basophilic staining, and rich in acid mucopolysaccharides (hyaluronic acid and chondroitin sulfate), as noted by the European Heart Journal 3, 6
Vascular elements include thin-walled blood vessels of varying caliber, hemorrhage and hemosiderin deposition common, and occasional thrombosis within tumor vessels, as reported by the European Society of Cardiology 3, 6

Surgical excision is the definitive and only established treatment for cardiac myxoma and should be performed urgently to prevent life-threatening complications, as recommended by the American College of Cardiology 1, 2, 3, 5
All symptomatic left atrial myxomas require surgical resection, according to the American Heart Association 2, 3
Surgical excision reduces stroke risk compared to conservative management, as noted by the European Society of Cardiology 1
The overall embolism rate is 25% in untreated patients, with 30-40% of myxomas causing embolic events, as reported by the American Heart Association 1, 2
Echocardiography (transthoracic and transesophageal) is the diagnostic technique of choice, as recommended by the European Society of Cardiology 3
Cardiac MRI or CT provides additional characterization for surgical planning, according to the European Society of Cardiology 3
More villous tumor morphology indicates greater embolic potential and urgency for surgery, as noted by the American Heart Association 1
Do not perform pericardiocentesis if pericardial effusion is present, as this may worsen hemodynamics, as warned by the European Heart Journal 6
Avoid anticoagulation alone as definitive therapy—it does not address the mechanical obstruction and may increase bleeding risk, as cautioned by the American Heart Association 1