Background: Cardiac syndrome X (CSX) is a condition characterized by chest pain with normal coronary arteries. However, its pathogenesis has not fully been understood yet. Red blood cell distribution width (RDW) has recently been suggested as a marker of acute and chronic cardiovascular diseases, while no data is available in patients with CSX.
Methods: One hundred and twenty consecutive patients with CSX and 102 normal controls were prospectively enrolled in this study. Blood samples were drawn from all individuals for measuring RDW and high-sensitivity C-reactive protein (CRP). The baseline data were compared between patients with CSX and normal controls.
Results: The RDW levels were significantly higher in patients with CSX than that in those with normal controls (13.1 ± 2.1 versus 12.3 ± 1.8, p=0.011). Moreover, the data showed that the levels of plasma CRP were marked higher in patients with CSX than those that were observed in normal controls (CRP: 2.8 ± 2.2 mg/L versus 2.0 ± 1.7 mg/dl, p=0.014). In addition, the multivariate analysis indicated that peripheral monocyte cell, CRP and RDW were the independent variables most strongly associated with CSX. In a receiver operating characteristic (ROC) curve analysis, we found that an RDW value of 12.8% was used as an effective cut-point in the segregation of the presence or absence of cardiac syndrome X, a sensitivity of 52.0% and a specificity of 65.4% were obtained. Finally, correlation analysis suggested that there was positive correlation between plasma levels of CRP and RDW levels (n=120, γ =0.381, P=0.013).
Conclusions: The present study, for the first time, demonstrated that elevated RDW and CRP levels were independently associated with the presence of CSX.