The associations of plasma phospholipid arachidonic acid with cardiovascular diseases: A Mendelian randomization study

Background: Arachidonic acid (AA), a major long-chain n-6 polyunsaturated fatty acid in animal foods, has been linked to inflammation, coagulation, and testosterone, which might relate to atherosclerotic cardiovascular diseases (ASCVD). We assessed the associations of genetically predicted plasma phospholipid AA with ASCVD and other CVD overall and by sex using Mendelian randomization (MR). Methods: We conducted two-sample MR, applying eight genetic variants, independent of a highly pleiotropic variant (rs174547), strongly (p < 5 x 10(-8)) predicting AA, primarily to summary statistics of genetic associations with ASCVD, including ischaemic heart disease (IHD), ischaemic stroke, and peripheral artery disease (PAD) from CARDIoGRAMplusC4D 1000 Genomes (60,801 IHD cases, 123,504 controls), MEGASTROKE (34,217 ischaemic stroke cases, 406,111 controls), and Pan-UK Biobank (n=similar to 420,531), and secondarily to genetic associations with other CVD from Pan-UK Biobank, Atrial Fibrillation Consortium, HERMES consortium, and FinnGen. We also assessed sex differences. Findings: Genetically predicted AA was associated with ASCVD (odds ratio (OR) per % of total fatty acids increase 1.03, 95% confidence interval (CI) 1.01 to 1.05) and its subtypes IHD (OR 1.03, 95% CI 1.004 to 1.05), ischaemic stroke (OR 1.03, 95% CI 1.004 to 1.06) and possibly PAD (OR 1.08, 95% CI 1.00 to 1.17), possibly more strongly in men than women. AA was also associated with venous thromboembolism (OR 1.12, 95% CI 1.05 to 1.19). A similar pattern was observed when using rs174547 to genetically predict AA. Interpretation: Our study suggests positive associations of AA with ASCVD and venous thromboembolism, with possibly stronger associations in men than women. (C) 2020 The Authors. Published by Elsevier B.V.