Pulmonary Arterial Thrombosis in Eisenmenger Syndrome Is Associated With Biventricular Dysfunction and Decreased Pulmonary Flow Velocity

Objectives: This study sought to determine what factors are associated with pulmonary artery thrombi in Eisenmenger patients. Background: Pulmonary artery thrombosis is common in Eisenmenger syndrome, although its underlying pathophysiology is poorly understood. Methods: Adult patients with Eisenmenger syndrome underwent computed tomography pulmonary angiography, cardiac magnetic resonance imaging, and echocardiography. Measurement of ventricular function, pulmonary artery size, and pulmonary artery blood flow were obtained. Hypercoagulability screening and platelet function assays were performed. Results: Of 55 consecutive patients, 11 (20%) had a detectable thrombus. These patients were older (p = 0.032), but did not differ in oxygen saturation, hemoglobin, or hematocrit from those without thrombus. Right ventricular ejection fraction by magnetic resonance imaging was lower in those with thrombus (0.41 ± 0.15 vs. 0.53 ± 0.13, p = 0.017), as was left ventricular ejection fraction (0.48 ± 0.12 vs. 0.60 ± 0.09, p = 0.002), a finding corroborated by tissue Doppler and increased brain natriuretic peptide. Those with thrombus also had a larger main pulmonary artery diameter (48 ± 14 mm vs. 38 ± 9 mm, p = 0.007) and a lower peak systolic velocity in the pulmonary artery (p = 0.003). There were no differences in clotting factors, platelet function, or bronchial arteries between groups. Logistic regression showed pulmonary artery velocity to be independently associated with thrombosis. Conclusions: Pulmonary arterial thrombosis among adults with Eisenmenger syndrome is common and relates to older age, biventricular dysfunction, and slow pulmonary artery blood flow rather than degree of cyanosis or coagulation abnormalities. Further work to define treatment efficacy is needed.