Relationships between CFVR and biomarkers
CFVR showed a significant negative correlation with proinflammatory biomarkers, as well as with B-type natriuretic peptide (BNP), d-dimer and troponin. Of those, CFVR had a weak to moderate correlation with C-reactive protein (p<0.001, r:-0.369), troponin (p=0.003, r:-0.470) and white blood cell count (p=0.043, r:-0.326); while it had a moderate to well correlation with BNP (p<0.001, r:-0.580), interleukin-6 (p<0.001, r:-0.597) and d-dimer (p<0.001, r:-0.561). Figure 1 summarizes correlations between CFVR and various biomarkers.
Of all biomarkers tested, fibrin-turnover marker d-dimer (AUC: 0.87 (0.73 – 1.00), p=0.001) had the highest accuracy for predicting CMD. For a cut-off value of 0.25, d-dimer had a sensitivity of 90% and specificity of 70% to predict CMD. Inflammatory biomarkers C-reactive protein (AUC: 0.81 (0.65-0.98), p=0.004) and Interleukin-6 (AUC: 0.80 (0.62-0.97), p=0.008) also offered good predictive accuracies, with the former having a sensitivity of 95% and specificity of 60% for a cut-off value of 6.5 mg/dl and the latter had a sensitivity of 82% and specificity of 80% for a cut-off value of 13.9 pg/ml. Other biomarkers with White blood cell count (AUC: 0.70 (0.49-0.90), p=0.07), BNP (AUC: 0.72 (0.52 – 0.92), p=0.042) and troponin (AUC: 0.72 (0.52 – 0.92), p=0.042) had smaller areas-under-curve to predict CMD (Figure 2).