Myocardial infarction (MI) often goes unrecognized in patients with chronic kidney disease (CKD) and it is associated with a significantly increased risk of death, according to researchers.

Of 18,864 participants in a population-based study who completed a baseline examination that included a 12-lead electrocardiogram (ECG), 852 (4.5%) had unrecognized MIs (UMIs) and 1,365 had recognized MIs (RMIs).

The prevalence of UMIs increased with lower levels of renal function and higher albuminuria levels. The prevalence was 4%, 6%, 6%, and 13% for subjects with an estimated glomerular filtrate rate (eGFR) of 60 or higher, 45-59.9, 30-44.9, or less than 30 mL/min/1.73 m2, respectively, investigators reported online ahead of print in Nephrology Dialysis Transplantation. The prevalence was 4%, 5%, 7%, and 10% among subjects with an albuminuria-to-creatinine ratio (ACR) of less than 10, 10-29.9, 30-299.9, and 300 or greater mg/g, respectively.

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The researchers, led by Dana V. Rizk, MD, of the University of Alabama in Birmingham, defined UMIs as the presence of an MI (according to the Minnesota ECG classification) in the absence of self-reported or RMI.

Among subjects with an eGFR below 60, UMI and RMI each was associated with a 65% increased risk of all-cause mortality compared with the absence of MI, after adjusting for multiple variables. UMI and RMI were associated with a 49% and 88% increased risk among subjects with an ACR of 30 mg/g or higher.

Dr. Rizk’s group found that traditional cardiovascular risk factors such as age, male gender, hypertension, and smoking were associated with a greater risk for UMI. “Interestingly, however, other risk factors like diabetes and dyslipidemia were not, raising the possibility that UMI may have a different mechanistic etiology than RMI,” the authors wrote.

Subjects were participants in the population-based REGARDS (Reasons for Geographic and Racial Differences in Stroke) study.

The authors noted that study strengths included the very large number of participants from throughout the United States, with an oversampling of African Americans. “This is particularly important because African Americans represent a substantial proportion of the CKD population, especially at the more advanced stages,” the researchers observed.

In a discussion of study limitations, they noted that their categorization of UMI versus RMI was based on self-report and may be subject to recall bias.