What is the indication for Dual Antiplatelet Therapy (DAPT) after Coronary Artery Bypass Grafting (CABG)?

Indications for DAPT After CABG

DAPT after CABG is indicated for patients with recent acute coronary syndrome (ACS) to complete 12 months of therapy, and should be considered for improving vein graft patency in all CABG patients, though the evidence is strongest for the ACS population. 1, 2

Primary Indication: Recent Acute Coronary Syndrome

• P2Y12 inhibitor therapy must be resumed postoperatively in ACS patients to complete a full 12 months of DAPT after the ACS event (Class I, Level of Evidence C-LD). 1, 2
• This recommendation applies regardless of whether the patient underwent PCI before CABG or was managed medically. 3
• Resume the P2Y12 inhibitor as soon as bleeding risk is controlled postoperatively, typically within 24-48 hours. 2

Secondary Indication: Prior Coronary Stenting

• Patients with prior coronary stents should resume P2Y12 inhibitor therapy postoperatively to complete the recommended DAPT duration for their stent type. 2
• Minimum duration is 1 month for bare metal stents and at least 6 months for drug-eluting stents. 2

Consideration for Stable Ischemic Heart Disease

• DAPT with clopidogrel for 12 months may be reasonable in stable ischemic heart disease patients without ACS to improve vein graft patency (Class IIb, Level of Evidence B-NR). 1, 2
• This represents a weaker recommendation with lower-quality evidence compared to the ACS indication. 1
• Meta-analysis data supports that DAPT reduces graft occlusion (11.3% vs 14.2%), major adverse cardiac events, and all-cause mortality compared to aspirin alone, without significantly increasing major bleeding. 4

Practical Algorithm for DAPT After CABG

All patients: Start aspirin 75-100 mg daily within 6-24 hours post-CABG once hemostasis is secured, continue indefinitely. 2

Add P2Y12 inhibitor if:

• Recent ACS (within 12 months): Yes, mandatory for 12 months total 1, 2
• Prior coronary stent: Yes, to complete minimum stent-specific duration 2
• Stable CAD without ACS: Consider for 12 months to improve graft patency 1, 2

P2Y12 Inhibitor Selection

• Clopidogrel 75 mg daily is the most studied and appropriate for most CABG patients. 2
• For ACS patients, ticagrelor may be preferred over clopidogrel as it demonstrated significant reduction in cardiovascular mortality. 2
• Prasugrel is reasonable for ACS patients without prior stroke/TIA who are not at high bleeding risk. 1

Critical Caveats

• High bleeding risk patients may warrant P2Y12 inhibitor discontinuation after 6 months rather than 12 months. 1, 3
• The PRECISE-DAPT score (≥25 indicates high bleeding risk) can identify CABG patients at increased bleeding risk with moderate accuracy. 5
• Add a proton pump inhibitor in patients at increased gastrointestinal bleeding risk (elderly, history of GI bleeding, chronic NSAID use). 2
• Mandatory reassessment at 12 months is required for all patients on DAPT to actively decide whether to continue or discontinue therapy. 3

Evidence Quality Note

The strongest evidence (Class I) supports DAPT resumption in ACS patients, while the recommendation for stable CAD patients is weaker (Class IIb). 1 Despite this, a 2018 meta-analysis of 11,135 patients demonstrated consistent benefits of DAPT across multiple outcomes without increased major bleeding. 4 Current UK practice shows 91% of cardiac surgeons prescribe DAPT postoperatively, though patient selection varies. 6