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Serum ferritin and acute coronary syndrome: A strong prognostic factor?
Letters to the Editor
129
Serum ferritin and acute coronary syndrome: A strong prognostic factor? Alberto Dominguez-Rodriguez a,⁎, Maria Carrillo-Perez Tome a, Celestino Hernandez-Garcia a, Eduardo Arroyo-Ucar a, Ruben Juarez-Prera a, Gabriela Blanco-Palacios a, Pedro Abreu-Gonzalez b a b
Hospital Universitario de Canarias, Department of Cardiology, Tenerife, Spain Universidad de La Laguna, Department of Physiology, Tenerife, Spain
a r t i c l e
i n f o
Article history: Received 20 June 2011 Revised 13 July 2011 Accepted 14 July 2011 Keywords: Ferritin Acute coronary syndrome Prognostic factor
Iron, an essential element for many important cellular functions in all living organisms, can catalyze the formation of potentially toxic free radicals. Ferritin, a major iron storage protein, is essential to iron homeostasis and it is involved in a wide range of physiologic and pathologic processes. In clinical medicine, ferritin is predominantly used as a serum marker of total body iron stores. In cases of iron deficiency and overload, serum ferritin serves a critical role in both diagnosis and management [1]. The results of literature have been conflicting regarding the association between ferritin and atherosclerosis, with some studies confirming, and others denying this possible deleterious effect [2]. In this line, we have conducted a study to determine the ability of serum ferritin to predict major adverse cardiovascular events (MACE) at 30 days in patients with acute coronary syndrome (ACS). We included one hundred and ninety six patients with a first non-ST elevation ACS (STEACS). All patients had typical chest pain at rest N5 min, with onset of symptoms within 48 h of enrolment, plus at least one of the following: (1) electrocardiographic signs of myocardial ischemia, i.e. N1 mm horizontal or downsloping ST-depression, T-wave inversion, or both; (2) abnormal cardiac troponin levels. We excluded patient with a history of alcohol consumption, anemia, infectious diseases, thyrotoxicosis, local or systemic inflammatory conditions, liver disease, end-stage renal disease and malignant tumors. The study was approved by the local research ethics committee and all subjects gave written informed consent before study entries. Patients were clinically followed during 30 days, and a common final date for all was used as the criterion for study. Importantly, at the end of follow-up the occurrence of clinical events was registered in all patients. MACE was defined as the combined result of cardiovascular death, non-fatal myocardial infarction or re-admission for unstable angina. Peripheral venous blood samples were obtained in all patients at hospital admission. Ferritin was determined with an electrochemiluminescence immunoassay on the Elecsys 1010 immunoassay analyzer (Roche Diagnostics, Mannheim, Germany). Coefficients of variation were 1.5% and 3.9% for intra- and inter-assay variability, respectively. Normal reference value of serum ferritin was between 20 and 300 ng/ml. Continuous variables are reported as mean± standard deviation, and categorical variables as frequencies and percentages. Comparisons between groups were carried out the by Mann–Whitney U-test (for continuous variables) and by Fisher's exact test or the Chi-square test for Abbreviations: AF, atrial fibrillation; LA, left atrium; LAD, left atrial dimension; BMI, body mass index. ⁎ Corresponding author at: Hospital Universitario de Canarias, Department of Cardiology, Ofra s/n La Cuesta E-38320, Tenerife. Spain. Tel.: +34 922679040; fax: +34 922 678460. E-mail address: [email protected] (A. Dominguez-Rodriguez).
discrete variables. A multivariate binary logistic regression analysis was performed to assess predictors associated with MACE at 30 days, including as independent variable ferritin and using a stepwise selection model. We included these variables with possible effects on the MACE at 30 days, such as age, gender, left ventricular ejection fraction, peak troponin I and hemoglobin levels. Optimal cutoff point of ferritin to predict MACE at 30 days was calculated with receiving operating characteristics (ROC) analysis. Differences were considered statistically significant if the null hypothesis could be rejected with N95% confidence. All probability values are 2 tailed. The SPSS 15 statistical software package (SPSS Inc) was used for all calculations. Baseline characteristics of subjects enrolled in the study are shown in Table 1. There were no significant differences between groups regarding age, sex, coronary risk factor, left ventricular ejection fraction, multivessel coronary artery disease and biochemical parameters. Serum ferritin levels were lower in ACS patients with MACE compared to without MACE at 30 days. Multivariate analysis showed that serum ferritin was a significant predictor of MACE at 30 days (OR ranging from [1.015, CI 95% 1.006–1.024, p=0.001] to [1.077, CI 95% 1.013–1.098, p b 0.001]) (Table 2). ROC analysis for ferritin showed an area under the curve of 0.68 (pb 0.001). An optimized cutoff point of 110.76 ng/ml showed 79% sensitivity and 62% specificity. The optimized point was obtained as the value that yielded the best sensitivity and specificity (Fig. 1). The major and original finding of our study is that in patients with a first STEACS and MACE had lower levels of serum ferritin compared with patients without MACE at 30 days. Likewise, ferritin levels on admission were associated with MACE at 30 days. The hypothesis that iron depletion may protect against coronary artery disease (CAD) was proposed by Sullivan in 1981 as an explanation for the sex-related differences in the heart disease rates [3]. Multiple lines of evidence support an important role of iron in promoting atherosclerosis and vascular accidents. Iron has been found to be increased in human atherosclerotic lesions compared with normal arterial wall [4]. However, clinical studies have given contradictory results regarding the association between various biochemical markers of body iron stores and the presence of CAD [2,5–9].
Table 1 Baseline characteristics of subjects enrolled in the study.
Age (years) Sex (male), n (%) Smoking, n (%) Hypertension, n (%) Hypercholesterolemia, n (%) Diabetes Mellitus, n (%) LVEF (%) Multivessel CAD, n (%) Patients treated with PCI, n (%) Biochemistry, Hemoglobin (g/dl) Cholesterol (mg/dl) Platelet count (× 109 l− 1) Creatinine (mg/dl) Peak troponin I (ng/ml) Serum ferritin (ng/ml)
MACE at 30 days (n = 39)
No MACE at 30 days (n = 157)
P value
65 ± 12 25 (64.1) 8 (20.5) 30 (76.9) 27 (69.2) 21 (53.8) 58 ± 9 12 (31) 14 (36)
66 ± 13 107 (68.2) 38 (24.2) 105 (66.9) 84 (55.3) 66 (42) 57 ± 8 64 (41) 48 (31)
0.73 0.62 0.78 0.22 0.07 0.18 0.39 0.76 0.90
13.1 ± 2.0 156.8 ± 41.1 211 ± 56 1.1 ± 0.9 10 ± 6 160.2 ± 158.8
12.7 ± 1.8 150 ± 44.4 227 ± 84 1.07 ± 1.0 12 ± 8 235.5 ± 168.2
0.22 0.38 0.28 0.69 0.14 0.01
MACE: major adverse cardiovascular events; LVEF: left ventricular ejection fraction; CAD: coronary artery disease; PCI: percutaneous coronary intervention.
130
Letters to the Editor
Table 2 Multivariate binary logistic regression analysis, including serum ferritin as the main independent variable. OR
95% confidence interval
P
Model 1 (unadjusted) Ferritin
1.015
1.006–1.024
0.001
Model 2 Ferritin Age
1.025 0.94
1.008–1.034 0.909–1.013
b0.001 0.18
Model 3 Ferritin Sex
1.049 0.728
1.004–1.056 0.089–1.195
b0.001 0.15
Model 4 Ferritin Left ventricular ejection fraction
1.038 1.142
1.017–1.050 0.977–1.153
b0.001 0.19
Model 5 Ferritin Peak troponin I
1.055 1.066
1.010–1.073 0.875–1.115
b0.001 0.79
Model 6 Ferritin Hemoglobin
1.077 1.113
1.013–1.098 0.997–2.053
b0.001 0.98
The majority of clinical studies [2] have reported increased ferritin levels in patients with CAD. Salonen et al. first reported a significant association between the serum ferritin level and the risk of myocardial infarction in a Finnish Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) of 1931 of middle-aged men during an average followup of 3 years [5]. They found that Finnish men with a serum ferritin ≥ 200 μg/l had a 2.2 higher risk of myocardial infarction than did men with lower serum ferritin. In a separate Rotterdam study involving a nested case–control cohort of subjects, Klipstein-Grobusch et al. showed a positive correlation between serum ferritin and the risk of myocardial infarction [10]. Likewise, Sempos et al. found no evidence of a direct association between iron status and the risk of developing CAD from the National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (NHEFS) that consisted of 4518 men and women who were followed for an average of 14 years [11]. It should be noted, however, that the study did not measure serum ferritin levels. Manttari et al. also reported no significant association between serum ferritin levels and the risk for developing CAD in a nested case–control study of Finnish Helsinki Heart Study cohort [12]. In our study, the patients with MACE at 30 days had lower levels of serum ferritin. To our knowledge, this finding has not been reported before. The association between STEACS patients, MACE and low ferritin is biologically plausible. Recently, Fan et al. have demonstrated in studies in vitro, that iron deficiency enhances atheroma inflammation through p38 mitogen activated protein kinase-nuclear factor-κB-extracellular matrix metalloproteinase inducer/matrix metalloproteinase-9 pathway [13]. Several studies have shown that ferritin protects cells from oxidative stress by maintaining iron homeostasis. Possibly, these low concentrations may have been the result of an increase in ferritin consumption, because STEACS patients who developed MACE have a higher oxidative stress [2]. Our study had some limitations. The inflammatory response is an integral component in STEACS patients. It has been shown that inflammation and acute phase response interact with the iron status at several levels [2]. In our study, we have not measured serum levels of inflammatory markers. On the other hand, the sample size was
0167-5273/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2011.07.052
Fig. 1. ROC analysis shows the power of ferritin to predict MACE at 30 days in STEACS patients. Area under the curve: 0.68 (CI 95% 0.57–0.78).
relatively small with a significant overlap of ferritin value in both groups, however with this number of patients and after adjusting by different confounders, we were able to show, that ferritin levels predict MACE at 30 days in STEACS patients. Further studies are needed to clarify the strength of these parameters of iron status in the pathogenesis of atherosclerosis or its clinical presentations. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology (Shewan and Coats 2010;144:1–2).
References [1] Knovich NA, Storey JA, Coffman LG, Torti SV, Torti FM. Ferritin for the clinician. Blood Rev 2009;23:95–104. [2] You SA, Wang Q. Ferritin in atherosclerosis. Clin Chim Acta 2005;357:1–16. [3] Sullivan JL. Iron and the sex difference in heart disease risk. Lancet 1981;1:1293–4. [4] Smith C, Mitchinson MJ, Aruoma OI, Halliwell B. Stimulation of lipid peroxidation and hydroxyl-radical generation by the contents of human atherosclerotic lesions. Biochem J 1992;286:901–5. [5] Salonen JT, Nyyssönen K, Korpela H, Tuomilehto J, Seppänen R, Salonen R. High stored iron levels are associated with excess risk of myocardial infarction in eastern Finnish men. Circulation 1992;86:803–11. [6] Liao Y, Cooper RS, McGee DL. Iron status and coronary heart disease: negative findings from the NHANES I epidemiologic follow-up study. Am J Epidemiol 1994;139:704–12. [7] Morrison HI, Semenciw RM, Mao Y, Wigle DT. Serum iron and risk of fatal acute myocardial infarction. Epidemiology 1994;5:243–6. [8] Reunanen A, Takkunen H, Knekt P, Seppänen R, Aromaa A. Body iron stores, dietary iron intake and coronary heart disease mortality. J Intern Med 1995;238:223–30. [9] Magnusson MK, Sigfusson N, Sigvaldason H, Johannesson GM, Magnusson S, Thorgeirsson G. Low iron-binding capacity as a risk factor for myocardial infarction. Circulation 1994;89:102–8. [10] Klipstein-Grobusch K, Koster JF, Grobbee DE, et al. Serum ferritin and risk of myocardial infarction in the elderly: the Rotterdam Study. Am J Clin Nutr 1999;69:1231–6. [11] Sempos CT, Looker AC, Gillum RF, Makuc DM. Body iron stores and the risk of coronary heart disease. N Engl J Med 1994;330:1119–24. [12] Mänttäri M, Manninen V, Huttunen JK, et al. Serum ferritin and ceruloplasmin as coronary risk factors. Eur Heart J 1994;15:1599–603. [13] Fan Y, et al. Iron deficiency activates pro-inflammatory signaling in macrophages and foam cells via the p38 MAPK-Nf-κβ pathway. Int J Cardiol in press, doi:10.1016/j. ijcard.2010.07.005
129
Serum ferritin and acute coronary syndrome: A strong prognostic factor? Alberto Dominguez-Rodriguez a,⁎, Maria Carrillo-Perez Tome a, Celestino Hernandez-Garcia a, Eduardo Arroyo-Ucar a, Ruben Juarez-Prera a, Gabriela Blanco-Palacios a, Pedro Abreu-Gonzalez b a b
Hospital Universitario de Canarias, Department of Cardiology, Tenerife, Spain Universidad de La Laguna, Department of Physiology, Tenerife, Spain
a r t i c l e
i n f o
Article history: Received 20 June 2011 Revised 13 July 2011 Accepted 14 July 2011 Keywords: Ferritin Acute coronary syndrome Prognostic factor
Iron, an essential element for many important cellular functions in all living organisms, can catalyze the formation of potentially toxic free radicals. Ferritin, a major iron storage protein, is essential to iron homeostasis and it is involved in a wide range of physiologic and pathologic processes. In clinical medicine, ferritin is predominantly used as a serum marker of total body iron stores. In cases of iron deficiency and overload, serum ferritin serves a critical role in both diagnosis and management [1]. The results of literature have been conflicting regarding the association between ferritin and atherosclerosis, with some studies confirming, and others denying this possible deleterious effect [2]. In this line, we have conducted a study to determine the ability of serum ferritin to predict major adverse cardiovascular events (MACE) at 30 days in patients with acute coronary syndrome (ACS). We included one hundred and ninety six patients with a first non-ST elevation ACS (STEACS). All patients had typical chest pain at rest N5 min, with onset of symptoms within 48 h of enrolment, plus at least one of the following: (1) electrocardiographic signs of myocardial ischemia, i.e. N1 mm horizontal or downsloping ST-depression, T-wave inversion, or both; (2) abnormal cardiac troponin levels. We excluded patient with a history of alcohol consumption, anemia, infectious diseases, thyrotoxicosis, local or systemic inflammatory conditions, liver disease, end-stage renal disease and malignant tumors. The study was approved by the local research ethics committee and all subjects gave written informed consent before study entries. Patients were clinically followed during 30 days, and a common final date for all was used as the criterion for study. Importantly, at the end of follow-up the occurrence of clinical events was registered in all patients. MACE was defined as the combined result of cardiovascular death, non-fatal myocardial infarction or re-admission for unstable angina. Peripheral venous blood samples were obtained in all patients at hospital admission. Ferritin was determined with an electrochemiluminescence immunoassay on the Elecsys 1010 immunoassay analyzer (Roche Diagnostics, Mannheim, Germany). Coefficients of variation were 1.5% and 3.9% for intra- and inter-assay variability, respectively. Normal reference value of serum ferritin was between 20 and 300 ng/ml. Continuous variables are reported as mean± standard deviation, and categorical variables as frequencies and percentages. Comparisons between groups were carried out the by Mann–Whitney U-test (for continuous variables) and by Fisher's exact test or the Chi-square test for Abbreviations: AF, atrial fibrillation; LA, left atrium; LAD, left atrial dimension; BMI, body mass index. ⁎ Corresponding author at: Hospital Universitario de Canarias, Department of Cardiology, Ofra s/n La Cuesta E-38320, Tenerife. Spain. Tel.: +34 922679040; fax: +34 922 678460. E-mail address: [email protected] (A. Dominguez-Rodriguez).
discrete variables. A multivariate binary logistic regression analysis was performed to assess predictors associated with MACE at 30 days, including as independent variable ferritin and using a stepwise selection model. We included these variables with possible effects on the MACE at 30 days, such as age, gender, left ventricular ejection fraction, peak troponin I and hemoglobin levels. Optimal cutoff point of ferritin to predict MACE at 30 days was calculated with receiving operating characteristics (ROC) analysis. Differences were considered statistically significant if the null hypothesis could be rejected with N95% confidence. All probability values are 2 tailed. The SPSS 15 statistical software package (SPSS Inc) was used for all calculations. Baseline characteristics of subjects enrolled in the study are shown in Table 1. There were no significant differences between groups regarding age, sex, coronary risk factor, left ventricular ejection fraction, multivessel coronary artery disease and biochemical parameters. Serum ferritin levels were lower in ACS patients with MACE compared to without MACE at 30 days. Multivariate analysis showed that serum ferritin was a significant predictor of MACE at 30 days (OR ranging from [1.015, CI 95% 1.006–1.024, p=0.001] to [1.077, CI 95% 1.013–1.098, p b 0.001]) (Table 2). ROC analysis for ferritin showed an area under the curve of 0.68 (pb 0.001). An optimized cutoff point of 110.76 ng/ml showed 79% sensitivity and 62% specificity. The optimized point was obtained as the value that yielded the best sensitivity and specificity (Fig. 1). The major and original finding of our study is that in patients with a first STEACS and MACE had lower levels of serum ferritin compared with patients without MACE at 30 days. Likewise, ferritin levels on admission were associated with MACE at 30 days. The hypothesis that iron depletion may protect against coronary artery disease (CAD) was proposed by Sullivan in 1981 as an explanation for the sex-related differences in the heart disease rates [3]. Multiple lines of evidence support an important role of iron in promoting atherosclerosis and vascular accidents. Iron has been found to be increased in human atherosclerotic lesions compared with normal arterial wall [4]. However, clinical studies have given contradictory results regarding the association between various biochemical markers of body iron stores and the presence of CAD [2,5–9].
Table 1 Baseline characteristics of subjects enrolled in the study.
Age (years) Sex (male), n (%) Smoking, n (%) Hypertension, n (%) Hypercholesterolemia, n (%) Diabetes Mellitus, n (%) LVEF (%) Multivessel CAD, n (%) Patients treated with PCI, n (%) Biochemistry, Hemoglobin (g/dl) Cholesterol (mg/dl) Platelet count (× 109 l− 1) Creatinine (mg/dl) Peak troponin I (ng/ml) Serum ferritin (ng/ml)
MACE at 30 days (n = 39)
No MACE at 30 days (n = 157)
P value
65 ± 12 25 (64.1) 8 (20.5) 30 (76.9) 27 (69.2) 21 (53.8) 58 ± 9 12 (31) 14 (36)
66 ± 13 107 (68.2) 38 (24.2) 105 (66.9) 84 (55.3) 66 (42) 57 ± 8 64 (41) 48 (31)
0.73 0.62 0.78 0.22 0.07 0.18 0.39 0.76 0.90
13.1 ± 2.0 156.8 ± 41.1 211 ± 56 1.1 ± 0.9 10 ± 6 160.2 ± 158.8
12.7 ± 1.8 150 ± 44.4 227 ± 84 1.07 ± 1.0 12 ± 8 235.5 ± 168.2
0.22 0.38 0.28 0.69 0.14 0.01
MACE: major adverse cardiovascular events; LVEF: left ventricular ejection fraction; CAD: coronary artery disease; PCI: percutaneous coronary intervention.
130
Letters to the Editor
Table 2 Multivariate binary logistic regression analysis, including serum ferritin as the main independent variable. OR
95% confidence interval
P
Model 1 (unadjusted) Ferritin
1.015
1.006–1.024
0.001
Model 2 Ferritin Age
1.025 0.94
1.008–1.034 0.909–1.013
b0.001 0.18
Model 3 Ferritin Sex
1.049 0.728
1.004–1.056 0.089–1.195
b0.001 0.15
Model 4 Ferritin Left ventricular ejection fraction
1.038 1.142
1.017–1.050 0.977–1.153
b0.001 0.19
Model 5 Ferritin Peak troponin I
1.055 1.066
1.010–1.073 0.875–1.115
b0.001 0.79
Model 6 Ferritin Hemoglobin
1.077 1.113
1.013–1.098 0.997–2.053
b0.001 0.98
The majority of clinical studies [2] have reported increased ferritin levels in patients with CAD. Salonen et al. first reported a significant association between the serum ferritin level and the risk of myocardial infarction in a Finnish Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) of 1931 of middle-aged men during an average followup of 3 years [5]. They found that Finnish men with a serum ferritin ≥ 200 μg/l had a 2.2 higher risk of myocardial infarction than did men with lower serum ferritin. In a separate Rotterdam study involving a nested case–control cohort of subjects, Klipstein-Grobusch et al. showed a positive correlation between serum ferritin and the risk of myocardial infarction [10]. Likewise, Sempos et al. found no evidence of a direct association between iron status and the risk of developing CAD from the National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study (NHEFS) that consisted of 4518 men and women who were followed for an average of 14 years [11]. It should be noted, however, that the study did not measure serum ferritin levels. Manttari et al. also reported no significant association between serum ferritin levels and the risk for developing CAD in a nested case–control study of Finnish Helsinki Heart Study cohort [12]. In our study, the patients with MACE at 30 days had lower levels of serum ferritin. To our knowledge, this finding has not been reported before. The association between STEACS patients, MACE and low ferritin is biologically plausible. Recently, Fan et al. have demonstrated in studies in vitro, that iron deficiency enhances atheroma inflammation through p38 mitogen activated protein kinase-nuclear factor-κB-extracellular matrix metalloproteinase inducer/matrix metalloproteinase-9 pathway [13]. Several studies have shown that ferritin protects cells from oxidative stress by maintaining iron homeostasis. Possibly, these low concentrations may have been the result of an increase in ferritin consumption, because STEACS patients who developed MACE have a higher oxidative stress [2]. Our study had some limitations. The inflammatory response is an integral component in STEACS patients. It has been shown that inflammation and acute phase response interact with the iron status at several levels [2]. In our study, we have not measured serum levels of inflammatory markers. On the other hand, the sample size was
0167-5273/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2011.07.052
Fig. 1. ROC analysis shows the power of ferritin to predict MACE at 30 days in STEACS patients. Area under the curve: 0.68 (CI 95% 0.57–0.78).
relatively small with a significant overlap of ferritin value in both groups, however with this number of patients and after adjusting by different confounders, we were able to show, that ferritin levels predict MACE at 30 days in STEACS patients. Further studies are needed to clarify the strength of these parameters of iron status in the pathogenesis of atherosclerosis or its clinical presentations. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology (Shewan and Coats 2010;144:1–2).
References [1] Knovich NA, Storey JA, Coffman LG, Torti SV, Torti FM. Ferritin for the clinician. Blood Rev 2009;23:95–104. [2] You SA, Wang Q. Ferritin in atherosclerosis. Clin Chim Acta 2005;357:1–16. [3] Sullivan JL. Iron and the sex difference in heart disease risk. Lancet 1981;1:1293–4. [4] Smith C, Mitchinson MJ, Aruoma OI, Halliwell B. Stimulation of lipid peroxidation and hydroxyl-radical generation by the contents of human atherosclerotic lesions. Biochem J 1992;286:901–5. [5] Salonen JT, Nyyssönen K, Korpela H, Tuomilehto J, Seppänen R, Salonen R. High stored iron levels are associated with excess risk of myocardial infarction in eastern Finnish men. Circulation 1992;86:803–11. [6] Liao Y, Cooper RS, McGee DL. Iron status and coronary heart disease: negative findings from the NHANES I epidemiologic follow-up study. Am J Epidemiol 1994;139:704–12. [7] Morrison HI, Semenciw RM, Mao Y, Wigle DT. Serum iron and risk of fatal acute myocardial infarction. Epidemiology 1994;5:243–6. [8] Reunanen A, Takkunen H, Knekt P, Seppänen R, Aromaa A. Body iron stores, dietary iron intake and coronary heart disease mortality. J Intern Med 1995;238:223–30. [9] Magnusson MK, Sigfusson N, Sigvaldason H, Johannesson GM, Magnusson S, Thorgeirsson G. Low iron-binding capacity as a risk factor for myocardial infarction. Circulation 1994;89:102–8. [10] Klipstein-Grobusch K, Koster JF, Grobbee DE, et al. Serum ferritin and risk of myocardial infarction in the elderly: the Rotterdam Study. Am J Clin Nutr 1999;69:1231–6. [11] Sempos CT, Looker AC, Gillum RF, Makuc DM. Body iron stores and the risk of coronary heart disease. N Engl J Med 1994;330:1119–24. [12] Mänttäri M, Manninen V, Huttunen JK, et al. Serum ferritin and ceruloplasmin as coronary risk factors. Eur Heart J 1994;15:1599–603. [13] Fan Y, et al. Iron deficiency activates pro-inflammatory signaling in macrophages and foam cells via the p38 MAPK-Nf-κβ pathway. Int J Cardiol in press, doi:10.1016/j. ijcard.2010.07.005