High stored iron levels are associated with excess risk of myocardial infarction in eastern Finnish men.

TLDR

Iron can induce lipid peroxidation and has been shown to promote ischemic myocardial injury in experimental models. The study tested whether high serum ferritin and high dietary iron intake increase the risk of acute myocardial infarction. The authors followed 1,931 asymptomatic men aged 42–60 from the Kuopio Ischaemic Heart Disease Risk Factor Study over an average of 3 years. Men with serum ferritin ≥200 µg/L had a 2.2‑fold higher risk of acute MI, and elevated ferritin was a strong risk factor overall—especially in those with LDL ≥5.0 mmol/L—while high dietary iron intake also increased risk.

Abstract

BACKGROUND Iron can induce lipid peroxidation in vitro and in vivo in humans and has promoted ischemic myocardial injury in experimental animals. We tested the hypothesis that high serum ferritin concentration and high dietary iron intake are associated with an excess risk of acute myocardial infarction. METHODS AND RESULTS Randomly selected men (n = 1,931), aged 42, 48, 54, or 60 years, who had no symptomatic coronary heart disease at entry, were examined in the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) in Eastern Finland between 1984 and 1989. Fifty-one of these men experienced an acute myocardial infarction during an average follow-up of 3 years. On the basis of a Cox proportional hazards model adjusting for age, examination year, cigarette pack-years, ischemic ECG in exercise test, maximal oxygen uptake, systolic blood pressure, blood glucose, serum copper, blood leukocyte count, and serum high density lipoprotein cholesterol, apolipoprotein B, and triglyceride concentrations, men with serum ferritin greater than or equal to 200 micrograms/l had a 2.2-fold (95% CI, 1.2-4.0; p less than 0.01) risk factor-adjusted risk of acute myocardial infarction compared with men with a lower serum ferritin. An elevated serum ferritin was a strong risk factor for acute myocardial infarction in all multivariate models. This association was stronger in men with serum low density lipoprotein cholesterol concentration of 5.0 mmol/l (193 mg/dl) or more than in others. Also, dietary iron intake had a significant association with the disease risk in a Cox model with the same covariates. CONCLUSIONS Our data suggest that a high stored iron level, as assessed by elevated serum ferritin concentration, is a risk factor for coronary heart disease.