Background: Impaired function of endothelium has been reported to be the initial step in atherosclerosis and thus may be seen as either independent cardiovascular risk factor or a marker of a present underlying abnormality.

Materials: 302 metabolic syndrome patients were examined (aged 36.4 ± 2.1 years, 55% males). Baseline examination included routine clinical examination, laboratory tests, cardiac ultrasound, ECG- and blood pressure monitoring. As endothelium-dependent vasoreactivity is advocated as a measure of vascular health, using a high-resolution ultrasound, the diameter of the brachial artery at rest and during reactive hyperaemia (endothelial-dependent flow-mediated dilatation, ΔFMD%) was measured. Study group comprised 104 participants (37.0 ± 3.6 years, 54% males), with endothelium dysfunction (ED) at baseline, ΔFMD 189.2 ± 19.7%. Control group included 198 patients without ED (35.8 ± 2.6 years, 56% males), ΔFMD 143.5 ± 10.3%. Coronary heart disease (CHD) was excluded using coronary angiography or stress echocardiography. Follow-up assessments were performed at two and seven years (including stress echocardiography).

Results: at two years follow-up 36.5% of study group patients developed CHD comparing to 13.1% among the controls (RR= 2.78, χ²₍₁₎=22.37); at seven years follow-up total CHD incidence was 0.865 for study group and 0.353 for controls (RR=2.45, χ²₍₁₎=71.71), fatal cardiovascular events were registered in 7.69% and 3.03% respectively (RR=2.57, χ²₍₁₎=3.325).

Conclusion: In patients with metabolic syndrome not having CHD endothelium dysfunction should be regarded as an independent risk factor.