BACKGROUND: The aim was to investigate whether functional and/or structural impairment of flow-mediated epicardial vasodilation (IEV) may precede coronary microvascular dysfunction (CMD) in a cardiometabolic risk population. RESULTS: The prevalence of diffuse coronary artery calcification was highest in G1 with 51 %, followed by G3 with 46 % and G2 with 34 %. The extent of CCS was mild-to-moderate and did not differ significantly among groups (p = 0.222). Overall, IEV was present in 60 %, while there was a comparable prevalence of IEV between G2 and G3 (27 % and 33 %, p = 0.27). The hyperemic MBF gradient was highest in G2, intermediate in G3, and lowest in G1 (-0.22 ± 0.11 and -0.18 ± 0.10 vs. 0.03 ± 0.08 mL/g/min
p <
0.001, respectively). CONCLUSIONS: In this cardio-metabolic risk population, in about one third of these symptomatic patients functional and/or structural impairment of flow-mediated epicardial vasodilation may precede coronary microvascular dysfunction.