Dual Antiplatelet Therapy After Myocardial Infarction

Introduction to DAPT

• The American College of Cardiology recommends dual antiplatelet therapy (DAPT) with ticagrelor and aspirin for at least 12 months after a myocardial infarction (MI), with consideration for extending therapy to 36 months in high-risk patients with low bleeding risk using the 60mg twice daily dose 1, 2

DAPT Duration and Dosage

• For patients with acute coronary syndrome (ACS) treated with coronary stent implantation, P2Y12 inhibitor therapy (ticagrelor, prasugrel, or clopidogrel) should be given for at least 12 months, and a daily aspirin dose of 81 mg (range 75-100 mg) should be used in combination 1
• In patients with ACS managed with medical therapy alone, P2Y12 inhibitor therapy (ticagrelor or clopidogrel) should be continued for at least 12 months 1
• The standard duration of DAPT is 12 months for all ACS patients, regardless of treatment method, with a consideration to stop DAPT after 6 months if the patient has a high risk of bleeding (PRECISE-DAPT ≥25) 3
• Low-dose aspirin (75-100mg) is recommended as part of DAPT 1, 3

DAPT Regimens

• The following dosing is recommended for P2Y12 inhibitors:

• Ticagrelor is recommended for ACS patients, with a loading dose of 180mg and a maintenance dose of 90mg twice daily, and is preferred over clopidogrel unless the patient has a high risk of bleeding 3
• Prasugrel is recommended for ACS patients who have undergone percutaneous coronary intervention (PCI), with a loading dose of 60mg and a maintenance dose of 10mg daily, but is contraindicated in patients with a history of intracranial hemorrhage, stroke, or transient ischemic attack (TIA) 3
• Clopidogrel is recommended for patients with stable coronary artery disease after stent placement, with a loading dose of 600mg and a maintenance dose of 75mg daily, and is an alternative for ACS patients who cannot take ticagrelor or prasugrel 3

Extended DAPT Option

• The American College of Cardiology suggests that ticagrelor 60mg twice daily (reduced dose) plus aspirin can be continued for up to 36 months in patients with prior MI 1-3 years previously and high-risk features, providing a 1.2-1.3% absolute reduction in ischemic events but a 1.2-1.5% increase in major bleeding 1, 2
• Patients with a high risk of ischemia and low risk of bleeding may be considered for extended DAPT beyond 12 months 3, 4

DAPT Discontinuation and Aspirin Therapy

• Discontinuation of P2Y12 inhibitor therapy after 6 months may be reasonable in ACS patients with drug-eluting stents (DES) who develop high bleeding risk, and aspirin should be continued indefinitely if possible 1
• Premature discontinuation of DAPT increases the risk of stent thrombosis, myocardial infarction, and death 4
• Discontinue ticagrelor 3-5 days before elective surgery, and continue aspirin if bleeding risk allows, as recommended by the European Society of Cardiology (ESC) 5, 3
• Resume ticagrelor with a loading dose of 180 mg within 24 hours after surgery if hemostasis is adequate, followed by a maintenance dose of 90 mg twice daily, as suggested by the ESC guidelines 5, 6

Management of Bleeding Risk

• Patients with a high risk of bleeding may need to have their DAPT regimen adjusted, and those who experience significant bleeding during DAPT therapy should have their treatment reassessed 3
• Regularly evaluate the risk of bleeding during treatment, and consider renal and hepatic function when selecting and dosing antiplatelet agents 3
• The addition of a proton pump inhibitor is recommended to reduce the risk of gastrointestinal bleeding 3

Guideline Recommendations

• The American College of Cardiology and European cardiology societies recommend a standard approach of 12 months of ticagrelor 90 mg twice daily + aspirin 75-100 mg daily, with a Class I recommendation and Level A/B evidence 7, 3, 4, 8, 9, 10
• Extended DAPT may be considered in select patients who have tolerated DAPT without bleeding complications, with a Class IIb recommendation and Level A/B evidence 4, 8, 10