Coronary microcirculatory vasodilator function in relation to risk factors among patients without obstructive coronary disease and low to intermediate Framingham score

Aims: The study aim was to evaluate the relation between the Framingham risk score (FRS) and the presence of coronary risk factors to coronary microcirculatory vasodilator function in patients with early coronary atherosclerosis. Methods and results: We evaluated 1063 patients (age: 50+12 years, 676 (64%) females) without significant narrowing (<30%) on coronary angiography who underwent invasive assessment of coronary endothelial function. Coronary blood flow (CBF) in response to the endothelium-dependent vasodilator acetylcholine was evaluated as well as the microvascular (endothelium- independent) coronary flow reserve (CFR) in response to intracoronary adenosine. Coronary blood flow and CFR were analysed in relation to the FRS and the presence of traditional and novel risk factors. The estimated 10 years risk in this group was 5.4+5.2%. Higher FRS was associated with lower CBF in men (P = 0.008), and was a univariate predictor of lower CFR (P = 0.012) in all patients. Multivariable analysis identified a higher FRS (P < 0.001), female sex (P < 0.001) and a positive family history of coronary disease (P = 0.043) as independent predictors of reduced CFR. Conclusion: In patients without obstructive coronary disease, a higher FRS was an independent predictor of reduced CFR. The current study provides insight into the relation between cardiac risk profile and coronary microcirculatory function, and suggests that impaired microcirculatory vasodilator function may be present even in patients with a low to intermediate Framingham score.