Duration of Dual Antiplatelet Therapy After Myocardial Infarction
Patients should remain on both aspirin and clopidogrel (Plavix) for at least 12 months after an MI, regardless of whether they received PCI, fibrinolytic therapy, or medical management alone. 1
Primary Recommendation Based on Most Recent Guidelines
The 2016 ACC/AHA focused update on dual antiplatelet therapy (DAPT) provides the most current evidence-based guidance:
- For ACS patients (including MI) treated with PCI and stent placement: Continue P2Y12 inhibitor therapy (clopidogrel, prasugrel, or ticagrelor) for at least 12 months after drug-eluting stent (DES) placement 1
- For ACS patients treated with medical therapy alone (no revascularization): P2Y12 inhibitor therapy should be continued for at least 12 months 1
- For STEMI patients treated with fibrinolytic therapy: Clopidogrel should be continued for a minimum of 14 days and ideally at least 12 months 1
Aspirin Dosing During and After DAPT
Aspirin should be continued indefinitely after MI at a maintenance dose of 81 mg daily. 1, 2
- During the acute phase, a loading dose of 162-325 mg is given 1
- After PCI or during maintenance therapy, 81 mg daily is preferred over higher doses to minimize bleeding risk while maintaining efficacy 1, 2
- Research confirms that 81 mg daily provides equivalent cardiovascular protection to 325 mg with significantly less bleeding risk 3
Clopidogrel (Plavix) Dosing
Clopidogrel 75 mg daily is the standard maintenance dose after the initial loading dose. 1
- Loading dose varies by timing: 300 mg if PCI within 24 hours of fibrinolytic therapy, or 600 mg if PCI more than 24 hours after fibrinolytic therapy 1
- For patients not receiving fibrinolytic therapy, standard loading is 300-600 mg 1
Duration Beyond 12 Months: When to Consider Extended DAPT
For select high-risk patients who tolerate DAPT without bleeding complications, continuation beyond 12 months may be reasonable. 1
The 2016 guidelines specify this applies to patients who:
- Have tolerated DAPT without bleeding complications during the first 12 months 1
- Are not at high bleeding risk (no prior bleeding on DAPT, no coagulopathy, no oral anticoagulant use) 1
- Have high thrombotic risk features such as complex coronary lesions, multiple stents, or other high-risk clinical factors 1
When to Stop DAPT Earlier Than 12 Months
For bare-metal stents (BMS), a minimum of 30 days of DAPT is required, though up to 12 months is still recommended. 1
- Patients at increased bleeding risk may receive shorter courses (minimum 2 weeks for BMS if bleeding risk is prohibitive) 1
- The decision to shorten DAPT duration must weigh stent thrombosis risk against bleeding risk 1
Critical Timing Considerations for CABG
If CABG becomes necessary, clopidogrel should be discontinued at least 5 days before surgery unless urgent revascularization benefits outweigh bleeding risks. 1
- Prasugrel requires 7 days of discontinuation 1
- Ticagrelor requires at least 5-7 days of discontinuation 1
- Aspirin is typically continued perioperatively 1
Common Pitfalls to Avoid
Do not discontinue DAPT prematurely in the first 12 months without compelling reasons (such as life-threatening bleeding or urgent surgery requiring discontinuation). 1 Early cessation dramatically increases the risk of stent thrombosis and recurrent MI, particularly in the first 6 months. 1
Do not use high-dose aspirin (325 mg) for maintenance therapy. 1, 2 Research demonstrates that 81 mg daily provides equivalent cardiovascular protection with 19% less bleeding compared to 325 mg. 3
Do not prescribe prasugrel to patients with prior stroke or TIA - this is a Class III (Harm) recommendation. 1