What are the indications and considerations for using aspirin (acetylsalicylic acid) as a prophylaxis in a pediatric patient?

Aspirin Prophylaxis in Pediatric Patients

Aspirin prophylaxis in pediatric patients is primarily indicated for Kawasaki disease (both acute treatment and long-term prevention of coronary thrombosis), acute ischemic stroke, cerebral sinovenous thrombosis, and specific cardiac conditions including mechanical heart valves and certain congenital heart diseases. 1, 2

Primary Indications for Aspirin Prophylaxis

Kawasaki Disease

This is the most common and well-established indication for aspirin use in children:

• Acute phase: High-dose aspirin 80-100 mg/kg/day divided into 4 doses for anti-inflammatory effects until fever resolves for 48-72 hours 1, 2
• Subacute/convalescent phase: Low-dose aspirin 3-5 mg/kg/day (or 1-5 mg/kg/day) once daily for antiplatelet effects for 6-8 weeks in patients without coronary abnormalities 1, 2
• Long-term prophylaxis: Indefinite low-dose aspirin 3-5 mg/kg/day for all patients with persistent coronary artery abnormalities (Class I recommendation) 1, 2

Dosing algorithm based on coronary involvement:

• Small coronary aneurysms: Low-dose aspirin 3-5 mg/kg/day indefinitely 1, 2
• Moderate aneurysms (4-6 mm): Low-dose aspirin plus clopidogrel 1 mg/kg/day (max 75 mg/day) 1, 2
• Giant aneurysms (≥8 mm): Low-dose aspirin plus warfarin (INR 2.0-3.0) or LMWH if warfarin difficult to regulate 1, 2

Acute Ischemic Stroke (AIS)

• Initial therapy: UFH, LMWH, or aspirin until dissection and cardioembolic causes excluded (Grade 1C) 1
• Long-term prophylaxis: Daily aspirin for minimum 2 years once dissection and cardioembolic causes excluded (Grade 2C) 1
• Moyamoya disease: Aspirin preferred over no treatment as initial therapy (Grade 2C) 1

Cerebral Sinovenous Thrombosis (CSVT)

• Aspirin is an acceptable alternative to UFH or LMWH for initial therapy until dissection and embolic causes excluded 1
• However, anticoagulation with UFH or LMWH is generally preferred over aspirin alone for CSVT 1, 3, 4

Cardiac Conditions

• Ventricular assist devices: Aspirin or aspirin plus dipyridamole within 72 hours of VAD placement 1
• Mechanical prosthetic heart valves: Follow adult recommendations, typically aspirin 75-100 mg daily added to warfarin when INR target is 2.5-3.5 1
• Asymptomatic carotid stenosis: Aspirin recommended in conjunction with carotid endarterectomy 1

Critical Safety Considerations and Contraindications

Reye Syndrome Risk

This is the most important pediatric-specific concern:

• All aspirin regimens must be discontinued during influenza or varicella (chickenpox) infection 1
• Switch to clopidogrel or LMWH during these infections to maintain antithrombotic coverage 1
• Annual influenza vaccination is mandatory for all children on long-term aspirin therapy 1, 2

Drug Interactions

• Never use ibuprofen in children taking aspirin for antiplatelet prophylaxis - ibuprofen antagonizes aspirin-induced irreversible platelet inhibition 1, 2

Bleeding Risk

• Monitor for signs of bleeding, particularly gastrointestinal bleeding and hemorrhagic stroke 5
• The increased relative risk of major bleeding with aspirin ranges from 54-62% compared to no treatment 5

Monitoring Requirements

For Kawasaki Disease Patients

• Echocardiography at diagnosis, 2 weeks, and 6-8 weeks after treatment 2
• For giant aneurysms: at least twice weekly echocardiography while coronaries rapidly expanding, then weekly for first 45 days, then monthly until third month 1
• ECG monitoring for silent myocardial infarction, especially in infants who may present with nonspecific symptoms (fussiness, vomiting, shock) 1

For Stroke Patients

• Repeat cerebrovascular imaging to guide ongoing antithrombotic therapy duration 1
• Clinical assessment for recurrent ischemic events or TIAs 1

Common Pitfalls to Avoid

1. Failing to discontinue aspirin during influenza/varicella infections - this is the primary cause of Reye syndrome in children on aspirin 1, 2

2. Using ibuprofen concurrently - completely negates aspirin's antiplatelet effects in patients with coronary aneurysms 1, 2

3. Stopping aspirin too early in Kawasaki disease - patients with any persistent coronary abnormalities require indefinite therapy 1, 2

4. Inadequate monitoring of high-risk patients - infants under 1 year with Kawasaki disease have highest risk for incomplete presentations and coronary aneurysms 2

5. Delaying live virus vaccines inappropriately - defer measles, mumps, rubella, and varicella vaccines for 11 months after high-dose IVIG (not related to aspirin itself) 2

When Aspirin is NOT Indicated

• Primary prevention of cardiovascular disease in children - there is no established role for aspirin in primary prevention in the pediatric population, unlike selected adult populations 6, 7, 8
• Routine thromboprophylaxis without specific cardiac or vascular indication - aspirin should only be used when specific high-risk conditions are present 1