Coronary vasomotor response incidence to intracoronary acetylcholine provocation test according to the severity of insignificant coronary artery stenosis in Korean population

Background Coronary artery spasm (CAS) is a cause of variant angina. However, the understanding of CAS patterns in the presence of mild-to-moderate coronary artery stenosis is limited. This study aimed to evaluate the incidence and patterns of CAS in patients with insignificant coronary artery stenosis using intracoronary acetylcholine (ACH) provocation test. Methods In this study, 6513 patients without significant coronary artery stenosis who underwent intracoronary ACH provocation test were enrolled. Patients were divided into three groups, based on the severity of coronary artery stenosis: the non group (stenosis <30%, n=2833), the mild group (30-49%, n=3278) and the moderate group (50-69%, n=402). Vasomotor responses were observed among three different groups. Results The baseline characteristics of the patients in the mild and moderate groups were worse than in the non group. They were older, had higher prevalence of hypertension, diabetes, dyslipidemia, and smoking habit. During the ACH test, CAS was observed in 58.1% of the overall population. The mild group (60.1%) and the moderate group (60.9%) showed a higher incidence than the non group (55.3%, P<0.001). In addition, among cases of CAS, the mild group (3.2%) and the moderate group (8.5%) responded more at a lowest dose of ACH than the non group (3.1%, P<0.001). Conclusion In patients with chest pain without significant coronary artery stenosis, CAS was observed in over half of the cases. Furthermore, CAS was found to be more frequent and more susceptible in patients with mild-to-moderate coronary artery stenosis compared with those without fixed stenosis.