BS12 IgM and IgG anti-oxidised low-density lipoprotein antibodies predict protective atherosclerotic characterstics on cardiac ct: a substudy of the scottish computed tomography of the heart (SCOT-HEART) trial

Background CT coronary angiography (CTCA)-derived low attenuation plaque has recently been identified as the strongest predictor of future myocardial infarction. Antibodies against oxidized low-density lipoprotein (oxLDL)/ malondialdehyde-modified LDL (MDA-LDL) are related to freedom from cardiovascular events. Objectives To investigate possible relationships between CTCA-derived atherosclerotic plaque subtypes and anti-oxLDL antibodies. Methods In a post-hoc analysis of the multicentre randomised controlled SCOT-HEART trial (Scottish COmputed Tomography of the HEART), we investigated the association between quantitatively assessed atherosclerotic plaque types on CTCA and IgM/ IgG anti-MDA-LDL or oxLDL. Serological biomarkers were measured using laboratory-developed enzyme-linked immunosorbent assays, and assessed versus imaging parameters. Results In 830 patients (52.8% male, 57.6±9.8 years), IgM anti-MDA-LDL was significantly inversely associated with coronary artery calcium score (p=0.0099) and obstructive coronary artery disease (OR 0.63 ([95% CI, 0.42-0.95], p=0.028). IgG anti-MDA-LDL strongly indicated protection from greater number of obstructed coronary arteries (OR 0.20 [95% CI 0.07-0.62], p=0.0048). Increasing tertiles of IgG anti-MDA-LDL related to less low attenuation plaque (p value for trend; unadjusted, p=0.021; adjusted for cardiovascular risk score, p=0.023). When using a predefined threshold of low attenuation plaque burden >4%, the highest tertile of IgG anti-MDA-LDL was significantly associated with low attenuation plaque at a threshold that confers a reduced likelihood of fatal or non-fatal myocardial infarction, withstanding adjustment for cardiovascular risk score (OR 0.58 [95% CI 0.34-0.96], p=0.037), p=0.027 for trend. Conclusions Both IgM and IgG anti-MDA-LDL antibodies are associated with protection from various atherosclerotic plaque characteristics. For the first time we provide evidence linking IgG anti-MDA-LDL antibodies with protection from low attenuation plaque, which is the strongest predictor of future fatal and non-fatal myocardial infarction. Conflict of Interest None