Clinical implications of low-dose aspirin on vasospastic angina patients without significant coronary artery stenosis; a propensity score-matched analysis.

Background: High-dose aspirin has been reported to exacerbate coronary artery spasm in patients with vasospastic angina. We investigated clinical implications of low-dose aspirin on vasospastic angina patients without significant coronary artery stenosis.

Methods: We included patients without significant coronary artery stenosis on coronary angiography (CAG) and with positive results on intracoronary ergonovine provocation test between January 2003 and December 2014. A total of 777 patients were divided into two groups according to prescription of low-dose aspirin at discharge: aspirin group (n=321) and non-aspirin group (n=456). The major adverse cardiovascular events (MACE), defined as composite outcomes of cardiac death, acute myocardial infarction, revascularization, or rehospitalization requiring CAG or medication change due to recurrent angina were compared.

Results: The aspirin group had significantly higher incidence of MACE (22.8% versus 12.1%; p=0.04) and had higher tendency for rehospitalization (20.6% versus 11.2%; p=0.08). All-cause mortality and cardiac death were similar between the two groups. After propensity score matching, the aspirin group had greater risk of MACE (hazard ratio [HR] 1.54; 95% confidence interval [CI], 1.04-2.28; p=0.037) and rehospitalization requiring CAG (HR, 1.33; 95% CI, 1.13-4.20; p=0.03), and a higher tendency for rehospitalization (HR, 1.40; 95% CI, 0.94-2.09; p=0.12).

Conclusion: In vasospastic angina without significant coronary artery stenosis, patients taking low-dose aspirin are at higher risk of MACE, driven primarily by tendency toward rehospitalization. Low-dose aspirin might be used with caution in vasospastic angina patients without significant coronary artery stenosis.