Procoagulant factors and the risk of myocardial infarction in young women

: Objectives: We investigated whether elevated levels of factor VIII, IX and XI is associated with myocardial infarction (MI) in young women. In addition, we studied ABO blood group, von Willebrand factor (VWF) and C‐reactive protein (CRP). Methods and results: We compared 200 women with MI before age 49 years with 626 controls from a population‐based case–control study. Mean levels of factor VIII activity (VIII), von Willebrand factor antigen (VWF), factor IX activity (IX) were higher in patients (133, 134 and 132 IU/dL) than in controls (111, 107 and 120 IU/dL, respectively). Mean levels of factor XI (XI) were equal in patients (114 IU/dL) and controls (113 IU/dL). The odds ratio (OR) for MI for blood group non‐O vs. O was 1.6 [95% confidence interval (CI) 1.1–2.3]. The OR adjusted for age, index year and area of residence for the highest quartile >150 IU/dL of factor VIII was 2.7 (95% CI 1.6–4.6), of VWF 4.7 (95% CI 2.3–9.7), of factor IX 2.6 (95% CI 1.3–5.4) and of factor XI 0.9 (95% CI 0.5–1.4), all compared with the lowest quartile <100 IU/dL. Conclusions: Non‐O blood group, high VWF, factor VIII and factor IX levels are associated with an increased risk of MI in young women, while high factor XI levels are not.