Abstract 4359695: Left Main Coronary Artery Obstruction from Mediastinal Mass: High-Risk PCI as Salvage Therapy

Description of Case: A 76-year-old female with a past medical history including HTN, DM, HLD, bilateral breast cancer (status post bilateral mastectomy and radiation), and prior thymoma presented with acute-onset dyspnea and chest pain. Initial evaluation revealed elevated troponin levels up to 9 ng/mL and sinus tachycardia with RBBB on ECG. CT chest demonstrated a large left anterior mediastinal mass infiltrating the pericardium, with suspected invasion into the left inferior pulmonary vein.Transthoracic echocardiography revealed a heterogeneous mediastinal mass invading the aortic root, causing extrinsic compression of the left main coronary artery, as well as involvement of the left superior pulmonary vein, left atrial lateral wall, and basal lateral left ventricular wall. A 2.1 x 2.1 cm echogenic mass was noted in the left atrial cavity. Initial coronary angiography revealed 75% narrowing of the left main coronary artery, but no intervention was performed. Surgical consultation with both cardiothoracic and thoracic surgery deemed the patient not a suitable candidate for resection or bypass due to extensive local invasion and overall frailty. A repeat angiogram one week later revealed progression to 90% left main stenosis, prompting an urgent high-risk PCI with successful stent placement. Discussion: Given rapid progression of left main coronary stenosis secondary to extrinsic tumor compression, and the patient’s inoperable status, a heart team approach led to the decision for high-risk PCI. The procedure was performed successfully, restoring perfusion and relieving symptoms.This case is an example of uncommon etiology of left main coronary artery compression from an invasive mediastinal tumor. When surgery was not feasible, PCI offered a successful alternative and served as a palliative measure when other options were not viable.