Markers of inflammation and coronary artery calcification: A systematic review

Objectives: The goal of this systematic review is to assess the cross-sectional relationship of inflammatory markers with the presence and extent of coronary artery calcium (CAC) to identify asymptomatic individuals with a higher risk of coronary heart disease (CHD). Background: Markers of subclinical inflammation and subclinical atherosclerosis have both been used to improve detection of individuals at high risk of developing cardiovascular disease. CAC has emerged as a surrogate maker for underlying coronary atherosclerosis, and has been shown to predict future CHD events. Although inflammation is intimately associated with atherosclerosis, and levels of inflammatory markers predict cardiovascular risk, the relationship of subclinical inflammatory markers with the burden of coronary atherosclerosis is not clear. Methods: Medline and Pub Med databases were searched for all studies assessing the relationship of inflammatory markers with CAC published till July 2007. Results: We found 12 studies that met our criteria. CRP, fibrinogen, metallic metalloproteinase-9 (MMP-9), monocyte chemotactic protein 1 (MCP-1), resistin, lipoprotein-associated phospholipase A₂ (Lp-PLA₂), IL-6, tumor necrosis factor alpha (TNF-alpha) and beta-fibroblast growth factor (bFGF) were used as inflammatory markers. There was a wide variation among studies with regards to population size, inclusion criterias, age range and techniques. It was observed that in almost all studies the relationship between inflammatory markers and CAC was weak, and was mostly found upon univariate analysis in women. However, this association was lost after correction for obesity and BMI. The data on the relationship of inflammation and CAC with progression of atherosclerosis is scarce and did not show any predictive benefits for future CHD. Conclusion: Variable associations between CAC and inflammatory markers were identified. In most studies where a positive relationship was found, this relationship disappeared after appropriate correction for the presence of traditional risk factors. Our data suggests that an approach in which inflammatory markers are used to further characterize risk in individuals with an established coronary artery disease burden is more warranted than using biomarkers as sole risk predictors of future CHD events. Large, well-planned comprehensive studies are required to identify the combined role of measuring inflammatory markers in assessment of atherosclerotic disease.