Safety and efficacy of low-dose aspirin in patients with coronary artery spasm: long-term clinical follow-up

Background: Aspirin is known to aggravate coronary artery spasm (CAS) regardless of the dose (100–325 mg/day). However, it is unclear whether low-dose aspirin (LDA; 100 mg) has deleterious impacts on the clinical course of CAS patients in the long-term. Thus, we investigated the impact of LDA on the long-term clinical outcomes of CAS patients.Methods: A total of 5,697 consecutive patients without significant coronary artery disease who underwent an acetylcholine provocation test from November 2004 to May 2015 were enrolled. Of these patients, 3,072 CAS patients were enrolled in the study and divided into two groups based on whether they took LDA: the LDA group (n=338) and the non-LDA group (n=2,734). All CAS patients were prescribed anti-anginal medication as appropriate. To adjust for any potential confounders that could cause bias, a propensity score matching analysis was performed using a logistic regression model. Results: After propensity score matching, two propensity-matched groups (524 pairs, 1,048 patients, C-statistic=0.827) were generated, and the baseline characteristics of the two groups were balanced. The two groups were showed no significant differences in any follow-up events, such as major adverse cardiac events and recurrent angina.Conclusions: The main finding of the present study is that the use of LDA did not affect cardiovascular events up to 5 years in CAS patients. Therefore, the prescription of LDA in these patients should be individualized considering their clinical status.