Do patients with myocardial infarction (heart attack) require anticoagulation?

From the Guidelines

Patients with myocardial infarction and atrial fibrillation (AF) should receive anticoagulation to prevent cardioembolic stroke, especially if they have additional risk factors such as history of hypertension, diabetes mellitus, previous stroke or transient ischemic attack, or ≥75 years of age. The selection of an anticoagulant agent, such as warfarin, dabigatran, apixaban, or rivaroxaban, should be individualized based on risk factors, cost, tolerability, patient preference, potential for drug interactions, and other clinical characteristics 1. Some key points to consider when deciding on anticoagulation for patients with myocardial infarction include:

• The presence of AF, which significantly increases the risk of cardioembolic stroke
• The presence of additional risk factors, such as history of hypertension, diabetes mellitus, previous stroke or transient ischemic attack, or ≥75 years of age
• The potential benefits and risks of anticoagulation, including the risk of bleeding
• The selection of an anticoagulant agent, which should be based on individual patient characteristics and preferences 1. In general, anticoagulation is not recommended for patients with myocardial infarction without AF, a prior thromboembolic event, or a cardioembolic source 1. However, dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 inhibitor is recommended for patients with myocardial infarction undergoing primary percutaneous coronary intervention (PCI). Key considerations for anticoagulation in patients with myocardial infarction include:
• The need for individualized decision-making based on patient characteristics and preferences
• The importance of weighing the potential benefits and risks of anticoagulation
• The selection of an anticoagulant agent based on risk factors, cost, tolerability, and other clinical characteristics 1.

From the FDA Drug Label

The results of the WARIS II study and 7th ACCP guidelines suggest that in most healthcare settings, moderate- and low-risk patients with a myocardial infarction should be treated with aspirin alone over oral vitamin-K antagonist (VKA) therapy plus aspirin In healthcare settings in which meticulous INR monitoring is standard and routinely accessible, for both high- and low-risk patients after myocardial infarction (MI), long-term (up to 4 years) high-intensity oral warfarin (target INR, 3.5; range, 3.0 to 4.0) without concomitant aspirin or moderate-intensity oral warfarin (target INR, 2.5; range, 2.0 to 3. 0) with aspirin is recommended. For high-risk patients with MI, including those with a large anterior MI, those with significant heart failure, those with intracardiac thrombus visible on echocardiography, and those with a history of a thromboembolic event, therapy with combined moderate-intensity (INR, 2.0 to 3. 0) oral warfarin plus lowdose aspirin (≤100 mg/day) for 3 months after the MI is suggested.

Patients with myocardial infarction who may need anticoagulation include:

• High-risk patients, such as those with:
  • Large anterior MI
  • Significant heart failure
  • Intracardiac thrombus visible on echocardiography
  • History of a thromboembolic event These patients may be treated with combined moderate-intensity oral warfarin (target INR, 2.0 to 3.0) and low-dose aspirin (≤100 mg/day) for 3 months after the MI 2.

From the Research

Anticoagulation Therapy for Myocardial Infarction Patients

Patients with myocardial infarction (MI) may require anticoagulation therapy to prevent recurrent cardiovascular events. The following points highlight the need for anticoagulation in these patients:

• Heparin therapy is indicated for acute myocardial infarction, particularly for patients at high risk of reinfarction or thromboembolism 3, 4.
• Warfarin is also recommended for patients with MI, especially those with anterior-wall MI, to prevent thromboembolism 4.
• The use of anticoagulants, such as heparin and warfarin, has been shown to reduce morbidity and mortality in patients with MI 4.
• Patients with high-risk features, such as non-Q-wave MI or additional risk factors for thromboembolism, may benefit from long-term anticoagulation therapy 4.

Risk Factors for Cardiovascular Events

Several risk factors have been identified that increase the likelihood of cardiovascular events in patients with MI, including:

• Age, hypertension, and prior cardiovascular events 5, 6.
• Renal dysfunction, heart failure, and peripheral artery disease 7, 5.
• Elevated white blood cell count and blood glucose levels 5.
• History of ventricular tachycardia or fibrillation, and prior coronary artery bypass grafting (CABG) 5.

Anticoagulation Therapy in High-Risk Patients

High-risk patients with MI, such as those with a history of stroke or MI, may benefit from anticoagulation therapy to prevent recurrent events 6.

• Patients with a history of MI have a higher risk of experiencing a second MI, while those with a history of stroke have a higher risk of experiencing a second stroke 6.
• The risk of subsequent events and cardiovascular death is increased over the whole systolic blood pressure (SBP) spectrum in patients with a history of MI or stroke 6.