Endothelial dysfunction and coronary artery disease: new insights from reactive hyperemia test

Aim: The percentage variation of Resistance Index (△RI%) after reactive hyperemia test at the brachial artery is a marker of endothelial dysfunction that could be used as a surrogate indicator for the extent of coronary artery disease (CAD). We assessed flow-mediated dilatation (FMD) and △RI% in 39 consecutive patients undergoing coronary angiography. Methods: Patients were classified in groups 0 to 3 according to the number of diseased vessels and the SYNTAX score was calculated. The hyperemia reactive test was performed 1 day before to 3 days after coronary angiography. Results: Both FMD and △RI% decreased significantly from groups 0 to 3 (ANOVA P < 0.001 and P = 0.002, respectively). Reduced △RI% was linearly associated with SYNTAX score (β = 0.34, P = 0.036). At multivariable modeling, impaired △RI% was the only significant independent predictor of the presence of CAD (OR = 1.28, 95%CI: 1.06-1.54, P = 0.01). Conclusion: This study shows that a reduced △RI% after reactive hyperemia test is observed in patients with CAD and that such reduction is related to the extent of the disease. Therefore, to evaluate FMD and △RI% at the brachial artery can reliably indicate the burden of CAD.