Background:Acute ECG changes during acetylcholine (Ach) provocation test may play an important role as a clinical parameter for the Ach-induced endothelial dysfunction.We investigated the association between ischemic ECG changes during the Ach provocation test and angiographic characteristics of Ach-induced endothelial dysfunction.Methods: A total 1085 pts with typical or atypical anginal symptoms underwent diagnostic coronary angiography (CAG) and Ach provocation test.Among them, 539 pts with(+)Ach-provocation test were divided into two groups according to ischemic ECG changes during the test.The ECG change group(n=64) was defined as ST- elevation or depression greater than 1mm during Ach provocation test.Most of the enrolled pts (n=475) didn���t show significant ECG change.We compared the presence of chest pain and angiographic characteristics of Ach-induced endothelial dysfunction between the two groups.Results:Baseline characteristics and coronary risk factors were similar between the two groups.A total 539 pts(248 men, Mean Age;58.01짹11.13years) showed significant Ach-induced endothelial dysfunction.ECG change group showed more frequent typical chest pain, angiographically more multiple, severe endothelial dysfunction compared with those of the pts without ECG change (Table).However,there was no differences in the length of endothelial dysfunction between the groups (p=0.448).Conclusion:When we categorized all the pts with Ach-induced endothelial dysfunction into two different groups according to ischemic ECG changes during Ach provocation test,ischemic ECG changes were clearly associated with chest pain, multi-vessel involvement and severity of Ach-induced endothelial dysfunction but not with the length of endothelial dysfunction.