Impact of low-dose aspirin on coronary artery spasm as assessed by intracoronary acetylcholine provocation test in Korean patients.

High-dose aspirin has been reported to aggravate coronary artery spasm (CAS). However, it is unknown whether low-dose aspirin (LDA; 100 mg) has deleterious impact on CAS. We assessed the impact of LDA on CAS induced by intracoronary acetylcholine (ACh) provocation test. A total of 2789 consecutive patients without significant coronary artery disease who underwent ACh test between November 2004 and March 2010 were enrolled. The patients were divided into two groups: the aspirin group taking LDA before ACh test (n=221) and the no aspirin group not taking aspirin (n=2568). At baseline, the prevalence of old age, diabetes mellitus, hypertension, and hyperlipidemia were higher in the aspirin group. During the ACh test, the incidence of significant CAS, ischemic chest pain, as well as severe and multivessel spasm was higher in the aspirin group. The response rate to lower ACh dose was higher in the aspirin group. Multivariate analysis showed that the previous use of LDA was an independent predictor of CAS (adjusted odds ratio, 1.6, 95% confidence interval, 1.0-2.3; p=0.031). However, it is likely that the association of LDA and CAS that we have observed is not causal but may be hypothesis generating due to significant baseline differences. Further, male gender, old age, lipid-lowering drugs, baseline spasm, and myocardial bridge were independent predictors of CAS. LDA was more frequently associated with CAS and ischemic symptoms, as well as severe and multivessel spasm, suggesting the patients who have received LDA would require more intensive medical therapies and close follow up.