What are the guidelines for aspirin and oral anticoagulation (OAC) in patients with Coronary Artery Disease (CAD) and Transient Ischemic Attack (TIA)?

Guidelines for Aspirin and Oral Anticoagulation in CAD and TIA

In patients with both CAD and TIA, lifelong aspirin 75-100 mg daily is recommended as the cornerstone of therapy, with oral anticoagulation (OAC) added only if there is a specific indication such as atrial fibrillation (AF), and when OAC is required, a direct oral anticoagulant (DOAC) is preferred over warfarin. 1

Antiplatelet Therapy for CAD with TIA (No AF or Other OAC Indication)

Primary Antithrombotic Strategy

• Aspirin 75-100 mg daily is recommended lifelong in patients with CAD (prior MI or revascularization) who have experienced a TIA 1
• Clopidogrel 75 mg daily is recommended as a safe and effective alternative to aspirin monotherapy in these patients 1
• Clopidogrel 75 mg daily may be considered in preference to aspirin specifically in patients with a history of ischemic stroke or TIA, though this is a weaker recommendation 1

Dual Antiplatelet Therapy (DAPT) Considerations

• After recent PCI-stenting in CAD patients, DAPT with aspirin 75-100 mg plus clopidogrel 75 mg daily for up to 6 months is recommended as the default strategy 1
• The combination of aspirin and clopidogrel is NOT routinely recommended for long-term secondary prevention in patients with TIA/stroke, as it increases hemorrhage risk without proportional benefit 1
• DAPT duration may be shortened to 1-3 months in patients at very high bleeding risk after PCI 1

Oral Anticoagulation When Indicated (e.g., AF)

Initiation and Selection of OAC

• When OAC is initiated in a patient with AF, a DOAC is recommended in preference to warfarin (VKA) 1
• Long-term OAC therapy is recommended in patients with AF and CHA2DS2-VASc score ≥2 in males and ≥3 in females 1

Timing of Anticoagulation After TIA

• For patients with TIA, anticoagulation can be started one day after the event 2
• For mild stroke, start after more than 3 days; for moderate stroke, after more than 6-8 days; for severe stroke, after more than 12-14 days 2
• Anticoagulation should not be started too early (less than 48 hours) after ischemic stroke as it may increase intracranial bleeding risk 2

Combination Therapy: OAC Plus Antiplatelet

After PCI in Patients Requiring OAC

The following stepwise approach is recommended: 1

1. Initial triple therapy (OAC + aspirin + clopidogrel):

   • Low-dose aspirin once daily is added to OAC and clopidogrel immediately after PCI 1

2. Early cessation of aspirin (≤1 week) after uncomplicated PCI 1

3. Continuation of OAC plus clopidogrel:

   • Up to 6 months in patients not at high ischemic risk 1
   • Up to 12 months in patients at high ischemic risk 1

4. Followed by OAC alone lifelong 1

Important Restrictions

• Ticagrelor or prasugrel are generally NOT recommended as part of triple antithrombotic therapy with aspirin and OAC 1
• A proton pump inhibitor is recommended in patients at increased risk of gastrointestinal bleeding for the duration of combined antithrombotic therapy 1

Special Considerations for CAD Patients

Rivaroxaban 2.5 mg Twice Daily Option

• In patients with stable CAD (including those with prior stroke/TIA), rivaroxaban 2.5 mg twice daily plus aspirin 75-100 mg once daily may be considered for reduction of major cardiovascular events 3
• This combination reduced the composite of stroke, MI, or cardiovascular death (HR 0.76,95% CI: 0.66-0.86) compared to aspirin alone 3
• This strategy is contraindicated in patients requiring dual antiplatelet therapy or full-dose oral anticoagulation 3

Patients with Acute MI and LV Thrombus

• Oral anticoagulation (INR 2.0-3.0) for at least 3 months and up to 1 year is reasonable 1
• Aspirin should be used concurrently in doses up to 162 mg/day (preferably enteric-coated) during oral anticoagulant therapy 1

Critical Pitfalls to Avoid

Contraindications to Dual Antiplatelet Therapy

• Active bleeding is an absolute contraindication to DAPT 4
• Severe untreated hypertension increases intracranial bleeding risk 4
• In cardioembolic TIA (especially with AF), long-term OAC is recommended instead of DAPT 1, 4

Drug Interactions

• Herbal medications (feverfew, garlic, ginkgo biloba, ginger, ginseng) may alter bleeding time and should be avoided with antithrombotic therapy 4
• St. John's wort may increase warfarin metabolism and interfere with anticoagulation 4

Aspirin Dosing

• The maintenance dose of aspirin should be 75-100 mg daily when used with DAPT or OAC to minimize bleeding risk while maintaining efficacy 1
• Higher doses (160-325 mg) do not provide proportionally greater benefit and increase bleeding risk 5, 6, 7