Aspirin for High-Risk Plaques on CT Coronary Angiography
Current clinical guidelines do not specifically recommend aspirin therapy based solely on the presence of high-risk plaque features detected on CT coronary angiography; however, guidelines do support aspirin use when high-risk plaques are accompanied by a coronary artery calcium (CAC) score ≥100, provided bleeding risk is not elevated. 1
CAC Score-Based Approach to Aspirin Therapy
The most practical guideline-based algorithm uses CAC scoring rather than qualitative plaque features alone:
CAC ≥100: The American College of Cardiology recommends considering low-dose aspirin (75-100 mg or 81 mg daily in US formulations) for primary prevention in patients with CAC scores ≥100, as this threshold identifies individuals who derive net cardiovascular benefit that exceeds bleeding risk. 1
CAC 0: The American Heart Association suggests that aspirin should not be initiated unless the ASCVD risk exceeds 20%, as bleeding risk outweighs cardiovascular benefit in this population. 1
CAC 101-400 and >400: The Cardiac Society of Australia and New Zealand recommends that patients in these ranges should receive preventive aspirin, as this is associated with substantial reduction in cardiovascular risk. 1
High-Risk Plaque Features and Clinical Context
While research demonstrates that specific plaque characteristics on CT angiography—including positive remodeling, low attenuation plaque, and spotty calcification—are significantly more frequent in acute coronary syndrome lesions, 2 current guidelines have not yet incorporated these qualitative features into formal aspirin recommendations. The presence of non-calcified plaque burden, even in a single segment, is associated with increased risk of adverse outcomes, 3 but this finding should prompt CAC scoring and comprehensive risk assessment rather than automatic aspirin initiation.
Critical Bleeding Risk Assessment
Before initiating aspirin based on CAC score or high-risk plaque findings, the European Society of Cardiology recommends excluding high bleeding risk patients, as bleeding risk can outweigh cardiovascular benefit. 1
Absolute contraindications include:
- Active gastrointestinal bleeding or peptic ulcer disease 1
- History of intracranial hemorrhage 1
- Severe thrombocytopenia 1
- Known aspirin allergy or hypersensitivity 1
Dosing and Adjunctive Therapy
Primary prevention dose: 75-100 mg daily (or 81 mg in US formulations) for patients with CAC ≥100. 1
Proton pump inhibitor: The European Society of Cardiology recommends adding a PPI for patients at increased gastrointestinal bleeding risk receiving aspirin. 1
Alternative antiplatelet: For patients with aspirin intolerance or hypersensitivity but CAC ≥100, the European Society of Cardiology recommends clopidogrel 75 mg daily as a safe and effective alternative (Class I, Level A recommendation). 1
Important Caveats
The 2019 American College of Cardiology/American Heart Association guidelines indicate that low-dose aspirin for primary prevention carries an increased risk of bleeding without net benefit in unselected populations. 4, 5 For patients over age 70 years, the balance appears to have greater risk than benefit. 4 Therefore, the presence of high-risk plaques on CT angiography alone—without quantitative CAC scoring and comprehensive bleeding risk assessment—is insufficient to justify aspirin initiation under current guidelines.
Aspirin remains strongly recommended for secondary prevention in patients with documented atherosclerotic cardiovascular disease or prior revascularization (Class I recommendation), 4 which would include patients with high-risk plaques who have experienced acute coronary syndromes or undergone percutaneous coronary intervention.