LAUSR

Background: Coronary function testing in patients with ischemia and nonobstructive coronary arteries (INOCA) commonly includes assessment of adenosine-mediated vasodilation and acetylcholine spasm provocation. The purpose of this study was to evaluate the diagnostic value of additional endothelial function testing for the diagnosis of vasomotor dysfunction in patients with INOCA. Methods: In this retrospective cohort study, we included patients with INOCA who underwent clinically indicated comprehensive coronary function testing. Endothelial dysfunction was defined as a <50% increase in coronary blood flow, determined by Doppler flow, and/or epicardial vasoconstriction compared to baseline, in response to low-dose acetylcholine. Coronary artery spasm (CAS) was defined as vasospastic angina or microvascular angina in response to coronary high-dose acetylcholine. An impaired adenosine-mediated vasodilation was defined as a coronary flow reserve <2.5 and/or hyperemic microvascular resistance ≥2.5. Results: Among all 110 patients, 79% had endothelial dysfunction, 62% had CAS, and 29% had an impaired adenosine-mediated vasodilation. Endothelial dysfunction was present in 80% of patients who tested positively for CAS and/or an impaired adenosine-mediated vasodilation. Endothelial function testing increases the diagnostic yield of coronary function testing that only incorporates adenosine testing and spasm provocation by 17% to 92%. Of patients with normal adenosine-mediated vasodilation and no inducible CAS, 68% had endothelial dysfunction. Conclusions: Concomitant endothelial dysfunction was prevalent in the vast majority of patients with INOCA with inducible CAS and/or an impaired adenosine-mediated vasodilation. In patients with INOCA without inducible CAS and normal adenosine-mediated vasodilation, two-thirds had endothelial dysfunction. These results indicate the relevance to perform endothelial function testing in patients with INOCA in view of its therapeutic implication.