RESUMO
BACKGROUND: The pathophysiology of microvascular angina (cardiac syndrome X, CSX), (effort-induced angina, a positive response to exercise stress testing and angiographically normal coronary arteries) has not been fully elucidated. Various pathogenic mechanisms have been proposed, amongst which coronary microvascular dysfunction features prominently. Management of patients with microvascular angina is often challenging as a substantial number of patients does not respond to conventional anti-anginal therapy. In this study, we sought to assess the association between brachial artery FMD, high-sensitive C-reactive protein (hs-CRP) and cardiovascular risk factors including obesity in patients with cardiac syndrome X. METHODS AND RESULTS: Thirty-four consecutive CSX patients (29 female, mean age 60 ± 9 years) were recruited from a specialised CSX clinic. Twelve asymptomatic subjects (10 female, mean age 51 ± 12 years) with comparable cardiovascular risk factor profile served as controls. All participants underwent standardized computer-assisted FMD measurements and assessment of hs-CRP concentrations at study entry. Body mass index (BMI), used as a general measure of obesity was calculated as weight (kilograms) divided by height (meters squared). Compared to controls, CSX patients had significantly higher hs-CRP concentrations (p = 0.003) and impaired FMD (p < 0.01). Moreover, among the CSX patients, a correlation between FMD and hs-CRP (r = -0.66, p < 0.01), FMD and BMI (r = 0.377, p = 0.028), and hs-CRP and BMI (r = -0.372, p = 0.030) was found. CONCLUSION: Impaired brachial artery FMD is significantly associated with elevated hs-CRP concentrations and BMI in patients with CSX. The results support the concept that low-grade inflammation and obesity may promote vascular dysfunction in these patients representing therapeutic targets for future research investigations.