What is the recommended antiplatelet therapy (Antiplatelet) after Coronary Artery Bypass Grafting (CABG) in Canadian Cardiovascular Society (CCS) guidelines?

Antiplatelet Therapy After CABG in Chronic Coronary Syndromes

All patients undergoing CABG for chronic coronary syndromes should receive low-dose aspirin (75-100 mg daily) started within 6-24 hours postoperatively and continued indefinitely, while dual antiplatelet therapy (DAPT) is not routinely indicated but may be considered in selected high-risk cases. 1, 2

Standard Aspirin Monotherapy (First-Line for CCS)

Aspirin monotherapy is the cornerstone of post-CABG antiplatelet therapy for chronic coronary syndromes:

• Initiate aspirin 75-100 mg daily within 6-24 hours after CABG once hemostasis is secured 1, 2
• Continue aspirin indefinitely for all CABG patients without contraindications 1
• Aspirin significantly improves saphenous vein graft patency, particularly during the first postoperative year, and reduces mortality, myocardial infarction, stroke, renal failure, and bowel infarction 1, 2
• For patients already on aspirin preoperatively, continue it through the perioperative period at low daily doses 1, 2

Critical timing consideration: Aspirin must be started within 48 hours postoperatively to maintain graft patency benefits; initiation after 48 hours loses the protective effect on saphenous vein graft patency 1

DAPT After CABG for CCS: Not Routine, But Consider in Select Cases

The 2024 ESC guidelines explicitly state that DAPT is NOT routinely indicated after CABG for chronic coronary syndromes 1. However, there are specific exceptions:

When to Consider DAPT in CCS Patients:

• Selected cases at increased risk of graft occlusion who are NOT at high bleeding risk 1
• The evidence shows DAPT reduces early saphenous vein graft occlusion (risk ratio 0.59) and all-cause mortality compared to aspirin alone, but increases major bleeding risk (OR 1.30) 3, 4

If DAPT is Used:

• Add clopidogrel 75 mg daily to aspirin 1, 2
• Duration: Consider 6-12 months, though optimal duration in pure CCS (without prior ACS or stenting) remains uncertain 1, 2
• Clopidogrel is the most studied P2Y12 inhibitor in CABG patients and has fewer adverse effects than ticlopidine 1

Important Distinction: CCS vs. ACS Context

This recommendation differs significantly if the patient had recent acute coronary syndrome or prior coronary stenting:

• Patients with prior ACS or coronary stents should resume P2Y12 inhibitor therapy postoperatively to complete 12 months of DAPT 1, 2
• In ACS patients undergoing CABG, DAPT is recommended, not just considered 1

Aspirin Alternative for Intolerance

• If aspirin is contraindicated or not tolerated, clopidogrel 75 mg daily is a reasonable alternative 1
• Ticlopidine offers no advantage over aspirin except in truly aspirin-allergic patients, but requires white blood cell monitoring due to neutropenia risk 1

Bleeding Risk Management

When using any antiplatelet therapy post-CABG:

• Add a proton pump inhibitor in patients at increased GI bleeding risk (elderly, history of GI bleeding, chronic NSAID use) 2
• PPIs effectively reduce gastrointestinal bleeding risk with antithrombotic therapy 2

Key Pitfalls to Avoid

Common errors in post-CABG antiplatelet management:

• Do not delay aspirin initiation beyond 48 hours - this eliminates the graft patency benefit 1
• Do not routinely use DAPT in stable CCS patients - the bleeding risk outweighs benefits in most cases 1
• Do not use dipyridamole or warfarin - they add nothing to aspirin's effect on graft patency and increase bleeding risk 1
• Do not use ticagrelor or prasugrel as part of routine post-CABG therapy in CCS - insufficient evidence in this population 1

Algorithm for Post-CABG Antiplatelet Therapy in CCS

Step 1: Start aspirin 75-100 mg daily within 6-24 hours post-CABG 1, 2

Step 2: Continue aspirin indefinitely 1

Step 3: Assess for high-risk features warranting DAPT consideration:

• Multiple vein grafts with poor target vessels
• Prior graft failure
• High atherosclerotic burden
• AND low bleeding risk 1

Step 4: If high ischemic risk AND low bleeding risk: Consider adding clopidogrel 75 mg daily for 6-12 months 1, 2

Step 5: If aspirin intolerant: Use clopidogrel 75 mg daily as monotherapy 1