Risk for CAD in the metabolic syndrome greater if IFG also present
MedWire News: Patients with the metabolic syndrome are more likely to have angiographically significant coronary artery disease (CAD) than patients without the syndrome, US researchers show.
Obstructive CAD becomes more prevalent as the number of the metabolic syndrome components increases, they say.
Additionally, significant macrovascular CAD is more likely if a patient has the metabolic syndrome and impaired fasting glucose (IFG) than if a patient has the metabolic syndrome alone.
Francisco Lopez-Jiminez (Mayo Clinic, Minnesota, USA) and colleagues identified 583 symptomatic patients without known CAD and with an abnormal SE.
Patients were divided into two groups according to the presence or absence of the metabolic syndrome and then subclassified according to their IFG status.
The team performed coronary angiography and compared the proportion of patients with obstructive CAD in each subgroup.
The authors found that patients with the metabolic syndrome had a trend toward having more obstructive CAD than those without the syndrome. In addition, the prevalence of obstructive CAD increased as the number of the syndrome components increased.
However, after exclusion of IFG as a component, the number of components was no longer predictive of obstructive CAD.
Regression analysis showed that after adjustment for pretest probability of CAD, smoking, and low density lipoprotein (LDL) cholesterol, the metabolic syndrome/IFG combination was a strong and independent predictor of obstructive CAD, at an odds ratio (OR) of 2.06.
By contrast, the metabolic syndrome without IFG (OR=0.91) and IFG without the metabolic syndrome (OR=1.23) were not significantly associated with obstructive CAD.
Diabetes was also an independent predictor of CAD, at an OR of 2.28.
"All of these findings point to the central role of hyperglycemia in disease progression in individuals with the metabolic syndrome," say the authors.
It seems that patients with the syndrome have different propensities toward having more advanced CAD, depending on the components making up the diagnosis of the metabolic syndrome, they add.
The team says one hypothesis that explains the association is that the metabolic syndrome patients with IFG are more likely to have higher circulating levels of insulin than those with normal blood glucose; hyperinsulilnemia in turn has been shown to be detrimental to endothelial function, leading to more accelerated atherosclerosis.
A second hypothesis is that this subgroup has lower levels of adiponectin, which is known for its atherogenic effects.
However, "the design of our study doesn't permit further evaluation of either of these hypotheses," write Lopez-Jiminez and team.
"Further studies with measurement of these biomarkers are warranted," they conclude.
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By Sally Robertson