Anticardiolipin antibody titre and plasma homocysteine level independently predict intima media thickness of carotid arteries in subjects with idiopathic antiphospholipid antibodies.

Abstract

This study evaluated whether IgG anticardiolipin antibody (aCL) titre and traditional risk factors for atherosclerosis bore any relationship to the intima media thickness (IMT) of carotid arteries of patients with idiopathic antiphospholipid antibodies (aPL). IMT was assessed by high-resolution sonography at the common carotid, carotid bifurcation and internal carotid in 42 (13 male, 29 female, mean age 31+/-10 years) aPL subjects, 29 with primary thrombotic antiphospholipid syndrome and 13 with persistence of aPL in the absence of any underlying disorder. In the same subjects the following were measured: plasma fibrinogen (FNG), von Willebrand factor (vWF), plasminogen activator inhibitor (PAI), homocysteine (HC), total cholesterol (CHO), triglycerides (TG), high density and low density lipoprotein (HDL and LDL), platelet numbers and aCL of IgG and IgM isotype. IMT of the internal carotid was greater in males than females (0.48+/-0.03 vs 0.39+/-0.01 mm, P=0.02). IMT of the carotid bifurcation was greater in thrombotic than nonthrombotic subjects (0.50+/-0.02 vs 0.42+/-0.02 mm, P=0.04). By simple regression, IMT of the common carotids correlated with age (P< 0.0001) IgG aCL titre (P=0.001), FNG (P=0.006), LDL (0.01), CHO (0.02) and PAI (P=0.02). IMT of the carotid bifurcation correlated with age (P=0.002), IgG aCL titre (P=0.0002), FNG (P=0.0001), HC (P=0.009), CHO (P=0.02), vWF (P=0.01) and number of thrombotic events (P=0.03). IMT of the internal carotids correlated with age (P=0.002), IgG aCL titre (P=0.0001), FNG (P=0.0008), PAI (P=0.002) and HC (P=0.01). By stepwise multiple regression analysis, IgG aCL titre independently predicted IMT at all carotid segments examined (P always <0.005). In addition, plasma FNG and HC also resulted independent predictors of IMT at the carotid bifurcation (P=0.001 and P<0.0001, respectively) and internal carotid (P=0.03 and P<0.0001, respectively). These data strongly support an atherogenic role for IgG aCL in patients with aPL. Measurement of plasma HC and FNG may help define aPL subjects at higher vascular risk who may require lowering of HC and FNG by vitamin and/or pharmacologic intervention.