Background:We investigated whether clinical and angiographic parameters related to Ach-induced endothelial dysfunction in octogenarians are different compared with those of younger pts.Methods:Total 1,049 pts [112 octogenarians(>70 years) and 937 younger pts] without coronary stenosis were enrolled.Ach provocation test was performed by injecting incremental doses of 20,50 and 100 µg to left coronary artery.Coronary artery endothelial dysfunction was defined as focal or diffuse severe transient luminal narrowing (>70%).We compared the pts���clinical and angiographic characteristics between octogenarians and younger pts.Results:Conventional coronary risk factors including HTN,DM and biochemical markers(HbA1c,hs-CRP,BNP) were higher in octogenarian group except smoking which was higher in younger pts, however,there was no difference in rate of positive Ach provocation test and associated angiographic characteristics such as multivessel spasm and frequency of inducible severe spasm(Table).The multivariate analysis indicated increasing age was strong independent predictors of positive Ach provocation test(OR 1.062,CI 1.015-1.111,p=0.009).Conclusions:In octogenarians,despite similar Ach-provocation test results compared with younger pts,increasing age was one of strong independent predictor of endothelial dysfunction.