Is Acetylsalicylic Acid (ASA) still recommended for primary prevention of cardiovascular disease and should it be continued in patients already taking it?

Aspirin for Primary Prevention of Cardiovascular Disease

Aspirin is generally not recommended for primary prevention of cardiovascular disease due to the comparable risk of bleeding that often outweighs modest cardiovascular benefits. 1

Current Recommendations for Primary Prevention

• Aspirin should not be routinely administered for primary prevention of atherosclerotic cardiovascular disease (ASCVD) in adults over 70 years of age, as the bleeding risk outweighs cardiovascular benefits 1
• Aspirin should not be used for primary prevention in individuals at increased risk of bleeding at any age 1
• Aspirin is not recommended for those at low risk of ASCVD, such as men and women aged <50 years with diabetes with no other major ASCVD risk factors 1
• Low-dose aspirin (75-100 mg daily) might only be considered for primary prevention among select adults 40-70 years of age who are at higher ASCVD risk but not at increased bleeding risk 1

Risk-Benefit Assessment

• Recent clinical trials show that aspirin has a modest effect on reducing ischemic vascular events (12% reduction in serious vascular events), with the absolute decrease in events depending on underlying ASCVD risk 1
• The main adverse effect is increased risk of gastrointestinal bleeding, which may be as high as 5 per 1,000 per year in real-world settings 1
• In the ASCEND trial, which studied patients with diabetes without established cardiovascular disease, aspirin reduced the risk of serious vascular events by 12% but increased major bleeding from 3.2% to 4.1% 1
• For adults with ASCVD risk >1% per year, the number of ASCVD events prevented will be similar to the number of bleeding episodes induced 1

Discontinuation of Aspirin in Primary Prevention

• For patients already taking aspirin for primary prevention, especially those over 70 years of age, discontinuation should be strongly considered as recent evidence shows the risk likely outweighs benefit 1
• For patients 40-70 years of age already on aspirin for primary prevention, reassessment of cardiovascular risk and bleeding risk is warranted 1
• If a patient has developed risk factors for bleeding while on aspirin for primary prevention, discontinuation is recommended 1

Special Considerations

• For patients with documented ASCVD, use of aspirin for secondary prevention has far greater benefit than risk; for this indication, aspirin is still strongly recommended 1
• Aspirin dosing: The most common low-dose tablet in the US is 81 mg; there is little evidence to support any specific dose, but using the lowest possible dose may help reduce side effects 1
• In the ADAPTABLE trial of patients with established cardiovascular disease, there were no significant differences in cardiovascular events or major bleeding between patients assigned to 81 mg versus 325 mg of aspirin daily 1
• Aspirin use in patients aged <21 years is generally contraindicated due to the associated risk of Reye syndrome 1

Decision-Making Algorithm for Aspirin in Primary Prevention

1. First, determine if the patient has established ASCVD (secondary prevention) - if yes, aspirin is recommended 1
2. If for primary prevention, check patient age:
   • If >70 years: Aspirin not recommended 1
   • If <40 years: Insufficient evidence to recommend aspirin 1
3. For patients 40-70 years, assess:
   • ASCVD risk factors (family history of premature ASCVD, hypertension, dyslipidemia, smoking, chronic kidney disease/albuminuria) 1
   • Bleeding risk factors (history of GI bleeding, peptic ulcer disease, age >70 years, thrombocytopenia, coagulopathy, CKD, concurrent use of medications that increase bleeding risk) 1
4. Only consider aspirin if high ASCVD risk AND low bleeding risk 1
5. For patients already on aspirin for primary prevention:
   • If >70 years or at increased bleeding risk: Discontinue 1
   • If 40-70 years: Reassess risk-benefit profile based on current guidelines 1