Evaluation of antibodies to β2‐glycoprotein 1 in the causation of coronary atherosclerosis as part of the antiphospholipid syndrome

Background: Anticardiolipin antibodies (aCL) are associated with accelerated coronary atherosclerosis. β2-glycoprotein 1 is a cofactor necessary for the binding of aCL. Aim: The aim of this study was to determine whether antibodies to β2-glycoprotein 1 (anti-β2GP1) predispose to coronary artery disease (CAD), and whether the measurement of anti-β2GP1 will be more useful than aCL alone in the evaluation of coronary risk. Methods: Persons who had undergone coronary angiography were invited to participate, and risk factors for coronary atherosclerosis recorded. IgG aCL and anti-β2GP1 were measured and fasting triglyceride (TG) and total cholesterol (TC) levels were determined. Angiographic score (AS) was defined as the number of diseased vessels (0, 1, 2, 3), (>50% stenosis). Ethics Committee approval was obtained. Statistical comparison used the Student's t test and Chi-squared test. Results: Ninety-seven subjects (63 male) with age range 38–81 years (mean 66.0) participated. There were 31 subjects with AS=0, 27 with AS=1, 22 with AS=2, and 17 with AS=3. The three subjects with positive aCL all had CAD, as did three of the four subjects with positive anti-β2GP1. Among patients with CAD, there was an equal incidence (4.5%, three/66) of aCL and anti-β2GP1, and an incidence of either aCL or anti-β2GP1 of 7.6% (five/66). Compared to the group with AS=0, those with AS=1, 2 or 3 comprised a higher mean age (p=0.001) however, there was no significant difference in the prevalence of other coronary risk factors between the two groups. There was no difference in the proportions of patients with either aCL or anti-β2GP1 in the group with AS=1, 2, or 3, compared to the group with AS=0 (5/66 c.f. 1/31, χ2=0.146, p>0.5). Conclusions: Our study has not supported an association between anti-β2GP1 and CAD. The measurement of anti-β2GP1 (or aCL) in the investigation of premature CAD is not justified on the basis of our results.