High prevalence of antiphospholipid antibodies in precapillary pulmonary hypertension

To assess prevalence and clinical associations of various antiphospholipid antibodies (aPL) in patients with primary and secondary pulmonary hypertension.

A prospective trial of aPL in 38 consecutive patients with pulmonary hypertension. Nine patients had primary pulmonary hypertension. Twenty-nine patients had pulmonary hypertension secondary to different etiologies: left heart failure, 8; congenital heart defect, 11; various lung diseases, 10. The search for aPL directed against 4 phospholipids (cardiolipin, phosphatidylserine, inositol, ethanolamine) was by ELISA.

Eleven patients (29%) had aPL, with various phospholipid specificities. Mean pulmonary artery pressure and mean pulmonary vascular resistance of aPL positive patients were not different from those of aPL negative patients. Mean pulmonary wedge pressure was significantly lower in aPL positive patients than those without aPL. Positive aPL were detected only in patients with precapillary pulmonary hypertension (11/30; 36.6%). The prevalence of aPL in primary (4/9; 44%) was not significantly different from aPL in secondary (7/29; 24%) pulmonary hypertension. There was no association between the presence of aPL and prior thrombosis or recurrent fetal losses.

The frequent positivity of aPL in precapillary pulmonary hypertension, irrespective of its cause and severity, suggests the existence of an associated endothelial disease. These antibodies might play a role in the initiation and/or progression of in situ thromboses frequently observed in precapillary pulmonary hypertension. Our results reinforce the necessity of longterm anticoagulant treatment in these patients.