Iron deficiency is associated with increased risk of coronary heart disease and cardiovascular mortality, according to a new study published in ESC Heart Failure, a journal of the European Society of Cardiology.

In this new study, the researchers aimed to examine the association between iron deficiency and cardiovascular disease in 12,164 individuals, median age 59 years, from three European population-based cohorts with women comprising 55% of the study population. All the study subjects were evaluated for the traditional cardiovascular risk factors and/or comorbid conditions; those with a history of coronary heart disease or stroke were not included in the study group. The median follow-up was for 13.3 years.

Iron deficient patients were categorized into two groups: absolute iron deficiency and functional iron deficiency.

Absolute iron deficiency was defined as ferritin less than 100 μg/L; ferritin below 30 μg/L was considered as severe absolute iron deficiency. Functional iron deficiency was defined as ferritin greater than100 μg/L or ferritin 100–299 μg/L and transferrin saturation (TSAT) less than 20%.

Sixty percent of the participants had absolute iron deficiency at the time of entry into the trial and 64% had functional iron deficiency. During the follow up period, 2212 deaths occurred and 573 of these were due to cardiac causes. 1033 persons were diagnosed with coronary heart disease and 766 patients suffered a stroke.

The risk of developing coronary heart disease was 24% (HR 1.15) higher in patients with functional iron deficiency compared to 20% (HR 1.20) increased risk in those with absolute iron deficiency.

While cardiovascular-related mortality (26%; HR 1.26) as well as all-cause mortality (12%; HR 1.12) was higher in the functional iron deficiency, no such association with mortality (all-cause mortality (HR 1.08) or cardiovascular mortality (HR 1.22) was seen for absolute iron deficient participants.

According to the authors, functional iron deficiency gives a more accurate picture of iron status as it also includes those individuals who have adequate iron stores, but low circulating iron. The prevalence of iron deficiency, particularly functional iron deficiency, was high in this study population. They were also more likely to develop heart disease and also more likely to die in the next decade.

This was an observational study and does not establish a cause-and-effect association between iron deficiency and heart disease, but it does show a link between the two and further suggests that the deaths and cases of new coronary heart disease in the next decade would not have occurred, if it were not for the baseline iron deficiency. Hence, functional iron deficiency may be considered as a risk factor for heart diseases.

Reference

1. Schrage B, et al. Association of iron deficiency with incident cardiovascular diseases and mortality in the general population. ESC Heart Fail. 2021 Oct 5. doi:10.1002/ehf2.13589.