Iron stores are not associated with acute myocardial infarction

Abstract

Background. This study evaluated the relation between body iron stores and coronary artery disease. It has been suggested that total body iron stores are an independent risk factor for acute myocardial infarction (AMI). Methods and Results. Our study population consisted of 46 932 members of a prepaid health plan who were ≥30 years old and who received a standard health check between 1969 and 1971. Blood collected during this examination was analyzed for serum iron and total iron-binding capacity. Transferrin saturation (TS), calculated as (serum iron/total iron-binding capacity) x 100, was categorized as low (≤10%), normal (11% to 61%), or elevated (≥62%). Hospital stays for AMI were identified from the health plan's computerized discharge records for its Northern California Region through December 31, 1991. Mean follow-up time was 14.1 years. During the follow-up period, 969 men and 871 women had an AMI-related hospital stay. Analysis of AMI-related hospital stays was performed overall and by sex. Age-adjusted incidence rates were obtained for each TS level, and proportional hazards regression models were used to assess the significance of TS as a risk factor for AMI, controlling for other known coronary disease risk factors. Our results did not show iron deficiency as defined by low TS to be protective against AMI. Subjects with increased iron stores indicated by TS ≥62% had a relative risk for AMI of 1.3, which was not statistically significant. Conclusions. Our observations do not support the hypothesis that coronary artery disease risk is related to iron stores.