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Vol.1, #5: May, 1998Published by: VirSci Corporation
© 1998 VirSci Corporation Complete Index Other Reviews in This
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Is Too Much Iron in the Blood Related to Heart Attack?
Paper: Association between body iron stores and the risk of acute
myocardial infarction in men
Authors: Tuomainen, T-P, et al
Ref: Circulation. 1998;97:1461-1466.
Type: Case-control study
Summary: Iron, a transition metal with oxidating
properties, has the ability to catalyze toxic redox reactions. Some
studies have demonstrated a relationship between excessive iron and
coronary heart disease (CHD), but the results have been inconsistent in
human populations. This study takes advantage of a recently developed
method of reliably assessing body iron stores -- the concentration ratio
of serum transferrin receptor to serum ferritin (TfR/ferritin) -- to
examine the impact of body iron stores on first acute myocardial
infarction (AMI) in a group of men in Finland.
Subjects were participants in the Kuopio Ischemic Heart Disease Risk
Factor Study, which prospectively examined a cohort of 1,931 men with no
clinical CHD at baseline. The TfR/ferritin ratio was compared between 99
men who had an AMI during an average 6.4 years of follow-up, and 98 men
without AMI who served as controls and were matched for age, examination
year, and residence. Transferrin receptor assays were used to determine
the TfR/ferritin ratio.
The mean TfR/ferritin ratio was significantly lower in cases (15.1)
than in controls (21.3), indicating a link between high body iron stores
and AMI. Other risk factors that differed between cases and controls
included smoking, serum HDL-cholesterol, maximal oxygen uptake, plasma
fibrinogen concentration, and serum copper concentration. In models
adjusting for strong 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 and 2.0-fold risk of AMI,
respectively, compared with men in the highest third. There was a
synergism between body iron stores and LDL-cholesterol in increasing the
risk of AMI. AMI risk also increased with dietary iron intake; for each
1 mg of iron daily, AMI risk increased 8.4%. The relationship between
AMI and TfR/ferritin ratio was strongest in men who did not use
antioxidative vitamins or aspirin.
The investigators noted that the risk of AMI due to body iron stores
may be greater in Finnish men than in Americans, because the use of
antioxidative vitamins and aspirin is rare in Finland and quite common
in America. More research is needed on this relationship. The
researchers concluded that men with high body iron stores have a twofold
to threefold increased risk of first AMI. They added, "Randomized
preventive trials concerning the effect of iron depletion [for example,
through blood donation] on coronary events are necessary to ultimately
verify or refute the iron-CHD hypothesis."
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