IRON DEFICIENCY AND ALL-CAUSE MORTALITY AFTER MYOCARDIAL INFARCTION

Introduction
Iron deficiency (ID) is a common comorbidity of cardiovascular diseases, including myocardial infarction (MI). However, the data on the clinical significance of ID in patients with MI are conflicting.

 
Aim
The aim of our study was to compare the association of different ID criteria with all-cause mortality after MI.

Sample and methodology
Consecutive patients hospitalized at a large tertiary heart centre for type 1 MI without previous history of coronary artery disease were included. We evaluated the association of different iron metabolism parameters with all-cause mortality during the follow-up by using Cox regression analysis.
Moreover, we analysed additional predictive value of different ID criteria to the GRACE (Global Registry of Acute Coronary Events) score.

Results
Of a cohort that included 1,156 patients (aged 64±12 years, 25% women), 194 (16.8%) died during the median follow-up of 3.4 years (IQR 626-1782 days). All ID criteria except for ferritin were independently associated with the all-cause mortality. However, only the iron level and our own Prague ID criteria in particular, provided additional prognostic value to the GRACE score.
A total of 51,7% of post-MI patients had low iron levels (≤13 µmol/L), and 57.6 % suffered from ID according to Prague ID criteria (at least one of these parameters: low iron level [≤12.8 µmol/l] and high sTfR [≥3 mg/L]).
After multivariate adjustment, iron level ≤13 µmol/L (HR 1.67, 95% CI 1.19-2.34) and the combination of iron level ≤12.8 µmol/L and sTfR ≥3 mg/L (HR 2.56, 95% CI 1.64-3.99) were associated with an increased risk of mortality.

Conclusion
ID affects more than half of patients with the first MI. The criteria based on iron and soluble transferrin receptor levels provide the best prediction of mortality, and should be evaluated in future interventional studies with intravenous iron therapy.