Association between body iron stores and the risk of acute myocardial infarction in men.

Epidemiological evidence concerning the role of iron, a lipid peroxidation catalyst, in coronary heart disease (CHD) is inconsistent. We investigated the association of the concentration ratio of serum transferrin receptor to serum ferritin (TfR/ferritin), a state-of-the-art measurement of body iron stores, with the risk of acute myocardial infarction (AMI) in a prospective nested case-control study in men from eastern Finland. Transferrin receptor assays were carried out for 99 men who had an AMI during an average 6.4 years of follow-up and 98 control men. Both the cases and the controls were nested from the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) cohort of 1931 men who had no clinical CHD at the baseline study. The controls were matched for age, examination year, and residence. AMIs were registered prospectively. Soluble transferrin receptors were measured by immunoenzymometric assay and ferritin concentration by radioimmunoassay from frozen baseline serum samples. The mean TfR/ferritin ratio was 15.1 (SE, 2.0) among cases and 21.3 (SE, 2.2) among controls (P=.035 for difference). In logistic regression models adjusting for other strongest risk factors for AMI and indicators of inflammation and alcohol intake, men in the lowest and second lowest thirds of the TfR/ferritin ratio had a 2.9-fold (95% CI, 1.3 to 6.6, P=.011) and 2.0-fold (0.9 to 4.2, P=.081) risk of AMI compared with men in the highest third (P=.010 for trend). These data show an association between increased body iron stores and excess risk of AMI, confirming previous epidemiological findings.