A 52-Year-Old Man With Chest Pain and Dyspnea

A 52-year-old man came to the cardiac surgery clinic for pulmonary thromboendarterectomy (PTE) evaluation. He had initially appeared at an outside hospital 1 year earlier, with chest pain and shortness of breath. He had no known chronic conditions. A CT pulmonary angiogram (CTPA) at that time showed a filling defect at the bifurcation of the main pulmonary artery. A transthoracic echocardiogram revealed mild mitral valve regurgitation, but otherwise the results were normal. As he was hemodynamically stable and not hypoxemic, he was treated solely by anticoagulation. Despite adhering to prescribed apixaban, he developed progressive dyspnea and reduced exercise tolerance over the subsequent year. A repeat CTPA performed 12 months after the initial presentation showed a persistent filling defect at the level of the pulmonary artery bifurcation, with a new extension now completely occluding the right main pulmonary artery. A pulmonary angiogram confirmed this complete occlusion, and right heart catheterization revealed precapillary pulmonary hypertension, with a mean pulmonary artery pressure of 50 mm Hg. His anticoagulation was transitioned to enoxaparin for presumed apixaban treatment failure, and an investigation for hypercoagulable conditions was initiated. His lupus anticoagulant test result was positive, but he did not meet the criteria for antiphospholipid syndrome because he was negative for anticardiolipin and β₂-glycoprotein antibodies. Assays for antithrombin III, protein C, prothrombin gene, and factor V Leiden mutations produced normal results.