From the Guidelines
Prophylactic aspirin is indicated for secondary prevention in patients with established coronary artery disease (CAD), but its use in primary prevention is more nuanced and should be individualized based on risk factors and bleeding risk. For patients with established CAD, defined as those with a history of acute coronary syndrome, prior revascularization, coronary stenoses > 50% by coronary angiogram, and/or evidence for cardiac ischemia on diagnostic testing, low-dose aspirin (75-100 mg daily) is recommended for long-term use 1. This recommendation is based on the American College of Chest Physicians evidence-based clinical practice guidelines, which suggest that single antiplatelet therapy with aspirin or clopidogrel is beneficial in reducing cardiovascular events in patients with established CAD.
The benefits of aspirin in secondary prevention are well-established, with studies demonstrating a reduction in cardiovascular events, including myocardial infarction, stroke, and death 1. However, the use of aspirin in primary prevention is more complex, and the decision to initiate aspirin therapy should be based on a careful assessment of the patient's individual risk factors and bleeding risk.
In general, aspirin is not recommended for primary prevention in patients without established cardiovascular disease, as the risks of bleeding may outweigh the benefits, particularly in older adults 1. However, patients who have had a heart attack, stroke, coronary stent placement, or coronary artery bypass surgery should take daily aspirin indefinitely unless contraindicated, as the benefits of aspirin in reducing cardiovascular events in these patients are well-established. Common contraindications to aspirin therapy include active bleeding, history of gastrointestinal bleeding, aspirin allergy, or high bleeding risk.
It is essential to note that the antiplatelet effect of aspirin works by irreversibly inhibiting cyclooxygenase-1 (COX-1), preventing the formation of thromboxane A2 and reducing platelet aggregation, which helps prevent arterial thrombosis in patients with atherosclerotic disease.
In summary, the use of prophylactic aspirin in CAD management should be individualized, with a focus on secondary prevention in patients with established CAD and a careful assessment of risk factors and bleeding risk in patients without established cardiovascular disease.
From the Research
Indications for Prophylactic Aspirin in CAD Management
- Aspirin is recommended for patients with coronary artery disease (CAD) for secondary prevention, particularly for those with a history of myocardial infarction, acute coronary syndrome, or those who have undergone percutaneous coronary intervention (PCI) 2, 3.
- The dosage of aspirin recommended is 75-100 mg daily as indefinite therapy for patients with stable CAD, post-myocardial infarction, post-acute coronary syndrome, and post-PCI 2.
- For patients with contraindications to aspirin, clopidogrel is recommended as monotherapy 2.
- Dual antiplatelet therapy with aspirin and clopidogrel is suggested for patients experiencing ST-segment elevation and non-ST-segment elevation acute coronary syndrome (ACS) 2, 3.
Considerations for Aspirin Therapy in Specific Patient Groups
- In patients with diabetes and no obstructive CAD, aspirin did not reduce major adverse cardiovascular events (MACE) or increase bleeding risk 4.
- Statin treatment, rather than aspirin, was associated with a significant reduction in MACE in patients with diabetes and no obstructive CAD 4.
- For primary prevention in patients with moderate risk for a coronary event, aspirin (75-100 mg/d) is recommended over no antithrombotic therapy or vitamin K antagonist 2.
Combination Therapy with Aspirin, Statin, and Blood Pressure-Lowering Agents
- The combined use of aspirin, a statin, and blood pressure-lowering agents is associated with a lower risk of vascular morbidity and mortality in patients with CAD 5.
- This combination therapy is recommended for patients with established CAD to reduce the risk of subsequent vascular events and all-cause mortality 5.