What is the role of anticoagulants in myocardial infarction (MI)?

Role of Anticoagulants in Myocardial Infarction

Anticoagulants play a critical role in the management of myocardial infarction (MI), with specific indications based on the type of MI, reperfusion strategy, and patient-specific factors. The use of anticoagulants is essential in both the acute phase and long-term management of MI patients to reduce mortality and morbidity.

Acute Phase Management

STEMI with Primary PCI

• For patients undergoing primary PCI for STEMI, anticoagulation is recommended during the procedure 1
• Unfractionated heparin (UFH) is the standard anticoagulant for primary PCI 1
• Fondaparinux is specifically not recommended for primary PCI (Class III recommendation) 1

STEMI with Fibrinolytic Therapy

• Anticoagulation is mandatory in patients treated with fibrinolytics until revascularization (if performed) or for the duration of hospital stay up to 8 days 1
• Preferred anticoagulants with fibrinolysis include:
  • Enoxaparin IV followed by subcutaneous administration (preferred over UFH, Class IA recommendation) 1
  • UFH given as a weight-adjusted IV bolus followed by infusion (Class IB recommendation) 1

NSTEMI

• Anticoagulation should be initiated promptly upon diagnosis for all NSTEMI patients 2
• Options include heparin or low molecular weight heparin for the initial hospitalization period for medically managed patients or until PCI 2

Long-Term Anticoagulation After MI

Standard Post-MI Antithrombotic Strategy

• Dual antiplatelet therapy (DAPT) consisting of aspirin plus a P2Y12 inhibitor (ticagrelor, prasugrel, or clopidogrel) is the standard of care for 12 months after MI 1
• Low-dose aspirin (75-100 mg) is indicated indefinitely (Class IA recommendation) 1

Specific Indications for Long-Term Anticoagulation

Left Ventricular Thrombus

• In patients with LV thrombus, anticoagulation should be administered for up to 6 months, guided by repeated imaging (Class IIa, C recommendation) 1

Patients with Existing Indications for Anticoagulation (e.g., Atrial Fibrillation)

• For patients with an indication for oral anticoagulation, anticoagulants are indicated in addition to antiplatelet therapy (Class I, C recommendation) 1
• Triple therapy (oral anticoagulant, aspirin, and clopidogrel) should be considered for 1-6 months according to bleeding and ischemic risk (Class IIa, C recommendation) 1
• After triple therapy, oral anticoagulation plus a single antiplatelet agent should be continued for up to 12 months, followed by anticoagulation alone thereafter 1
• The use of ticagrelor or prasugrel is not recommended as part of triple antithrombotic therapy (Class III, C recommendation) 1

High Ischemic Risk with Low Bleeding Risk

• In low bleeding-risk patients receiving aspirin and clopidogrel, low-dose rivaroxaban (2.5 mg twice daily) may be considered (Class IIb, B recommendation) 1
• This recommendation is based on the ATLAS ACS 2-TIMI 51 trial, which showed that rivaroxaban 2.5 mg twice daily reduced major adverse cardiovascular events but increased non-CABG-related major bleeding 1

Special Considerations

Elderly Patients

• Elderly patients (≥75 years) have higher bleeding risk with anticoagulation and require careful monitoring 1
• Dose adjustments may be necessary based on renal function and concomitant medications 1

Bleeding Risk Management

• A proton pump inhibitor (PPI) in combination with DAPT is recommended in patients at high risk of gastrointestinal bleeding (Class I, B recommendation) 1
• For patients at high risk of severe bleeding complications, discontinuation of P2Y12 inhibitor therapy after 6 months should be considered (Class IIa, B recommendation) 1

Historical Perspective

• Earlier studies like WARIS and WARIS 2 demonstrated that warfarin use was associated with significant reductions in mortality (24%), nonfatal recurrent MI (34%), and cerebrovascular accidents (55%) compared with placebo in patients who mostly did not receive reperfusion therapy 1
• However, the increased risk of bleeding and need for frequent monitoring have limited the routine use of oral anticoagulants post-MI in contemporary practice 1

Conclusion

The role of anticoagulants in MI is well-established for specific indications. While antiplatelet therapy remains the cornerstone of post-MI management, anticoagulation plays a crucial role in the acute setting for all MI patients and in the long-term for selected high-risk patients, particularly those with LV thrombus or other indications for anticoagulation such as atrial fibrillation.