ABSTRACT
Background: Coronary vasomotor dysfunction, an important underlying cause of angina and non-obstructive coronary arteries (ANOCA), encompassing coronary vasospasm, coronary endothelial dysfunction and/or coronary microvascular dysfunction, is clinically assessed by invasive coronary function testing (ICFT). As ICFT imposes a high burden on patients and carries risks, developing non-invasive alternatives is important. We evaluated whether coronary vasomotor dysfunction is a component of systemic microvascular endothelial and smooth muscle dysfunction, and can be detected using laser speckle contrast analysis (LASCA). Methods: Forty-three consecutive ANOCA patients underwent ICFT, with intracoronary acetylcholine, adenosine, and flow measurements, to assess coronary vasomotor dysfunction. Cutaneous microvascular function was assessed using LASCA, combined with vasodilators acetylcholine, sodium-nitroprusside and insulin and using EndoPAT, by measuring the reactive hyperemia index (RHI). Results: Of the 43 included ANOCA patients (79% women, 59±9 years), 38 patients had coronary vasomotor dysfunction, including 28 with coronary vasospasm, 26 with coronary endothelial dysfunction and 18 with coronary microvascular dysfunction, with overlapping endotypes. Patients with and without coronary vasomotor dysfunction had similar peripheral flow responses to acetylcholine, insulin, and RHI. In contrast, coronary vasomotor dysfunction was associated with lower peripheral flow responses to sodium-nitroprusside (p<0.001). An absolute flow response to sodium-nitroprusside of 83.95APU resulted in 86.1% sensitivity and 80.0% specificity for coronary vasomotor dysfunction (area under the ROC curve: 0.883; p=0.006). Conclusions: This study provides evidence of a systemic vascular smooth muscle dysfunction in ANOCA patients with coronary vasomotor dysfunction, and diagnostic value of peripheral microvascular function testing as non-invasive tool for detecting coronary vasomotor dysfunction.