While the efficacy of aspirin for the secondary prevention of cardiovascular disease is evident, the effect of aspirin for primary prevention is unclear. The use of aspirin reduces cardiovascular mortality and myocardial infarction but increases side effects such as bleeding. Therefore, the use of aspirin for primary prevention in people without cardiovascular disease should be determined by individual risk and clinical benefit. The European guidelines have been changed to not recommend aspirin use in people without cardiovascular disease, but there are still people taking aspirin for primary prevention. The purpose of this study is to investigate the effect of aspirin withdrawal on cardiovascular events in patients without cardiovascular disease.

This is a single center, prospective, randomized clinical study evaluating the safety and efficacy of withdrawal of aspirin among patients with moderate or high cardiovascular risk.

Patients taking aspirin will be randomly assigned to a group that maintains taking aspirin and a group that discontinues to take aspirin by 1:1 manner. The follow-up duration is five years and clinical outcomes will be investigated.

Inclusion Criteria:

• Adults aged 19-80 years old
• Subjects who are taking for more than 12 months
• Subjects with moderate or high cardiovascular risk based on cardiovascular risk classification of 2015 Korea Society of Lipidology And Atherosclerosis guideline or 2004 American Heart Association guideline: 1) moderate risk: people with ≥2 major risk factors, 2) high risk: people with carotid atherosclerosis, abdominal aortic aneurysm, or diabetes, who is taking statin
• Subjects who voluntarily participate in the study and sign informed consent form

Exclusion Criteria:

• Subjects with a history of major cardiovascular disease confirmed by medical history and medical history; myocardial infarction, angina pectoris, coronary angioplasty, coronary artery bypass surgery, peripheral vascular disease, ischemic stroke, transient ischemic attack
• Subjects has any contraindication to use of aspirin or hypersensitivity to aspirin
• Subjects with atrial fibrillation
• Subjects who are taking anti-platelet agents other than aspirin or anticoagulants
• Subjects who have been diagnosed with cancer within the last 5 years
• Pregnant women or those who have pregnancy plan after enrolling in this study