From the Guidelines
Apixaban is the most appropriate oral antithrombotic therapy for DR at this time. For a 73-year-old female with cardioembolic stroke from nonvalvular atrial fibrillation (NVAF), direct oral anticoagulants (DOACs) like apixaban are preferred over antiplatelet therapy, as supported by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. Apixaban is typically dosed at 5 mg twice daily, though a reduced dose of 2.5 mg twice daily may be considered if the patient meets two of the following criteria: age ≥80 years, body weight ≤60 kg, or serum creatinine ≥1.5 mg/dL, as noted in the AVERROES trial 1. Some key points to consider when selecting antithrombotic therapy for patients with nonvalvular AF include:
- The risk of thromboembolism, which can be assessed using the CHA2DS2-VASc score 1
- The risk of bleeding, which can be influenced by factors such as age, renal function, and concomitant use of antiplatelet agents 1
- The patient's values and preferences, which should be taken into account when making decisions about antithrombotic therapy 1 Apixaban should be started promptly, typically within 4-14 days after stroke onset, depending on the stroke severity, as recommended by the American Heart Association/American Stroke Association 1. In this case, with an NIHSS score of 4 indicating a mild stroke, treatment could begin within 3-5 days if no hemorrhagic transformation is detected on follow-up imaging. Apixaban is superior to antiplatelet therapy for secondary stroke prevention in NVAF because it directly inhibits factor Xa in the coagulation cascade, effectively preventing thrombus formation in the left atrium where cardioembolic strokes typically originate, as demonstrated in the ARISTOTLE trial 1. Antiplatelet agents like aspirin, clopidogrel, or dipyridamole are insufficient for stroke prevention in NVAF as they only affect platelet aggregation and not the coagulation cascade that leads to atrial thrombus formation, as noted in the ACTIVE trials 1.
From the FDA Drug Label
Oral anticoagulation therapy with warfarin is recommended in patients with persistent or paroxysmal AF (PAF) (intermittent AF) at high risk of stroke (i.e., having any of the following features: prior ischemic stroke, transient ischemic attack, or systemic embolism, age >75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus)
The most appropriate oral antithrombotic therapy for DR at this time is not explicitly stated in the provided drug label, as it does not mention apixaban, aspirin, or aspirin plus clopidogrel/dipyridamole as options for nonvalvular atrial fibrillation (NVAF) in the context of acute stroke. However, based on the information provided, warfarin is recommended for patients with NVAF at high risk of stroke, which includes those with a history of hypertension or diabetes mellitus. Since DR has NVAF, hypertension, and diabetes mellitus, warfarin could be considered, but the label does not provide direct guidance on the use of other antithrombotic agents in this specific scenario 2.
From the Research
Oral Antithrombotic Therapy for Cardioembolic Stroke
The patient, DR, has been diagnosed with cardioembolic stroke from nonvalvular atrial fibrillation (NVAF). Considering her past medical history and current condition, the most appropriate oral antithrombotic therapy needs to be determined.
Options for Oral Antithrombotic Therapy
- Apixaban
- Aspirin
- Aspirin plus clopidogrel
- Aspirin plus dipyridamole
Evidence-Based Recommendations
Studies have shown that apixaban, dabigatran, rivaroxaban, or warfarin can be considered for the prevention of stroke and systemic embolism in patients with NVAF 3. Apixaban has been found to be associated with a lower risk of stroke/systemic embolism and major bleeding compared to rivaroxaban and warfarin 4. Additionally, apixaban has been shown to have a more favorable effectiveness, safety, and persistence profile compared to other oral anticoagulants 5.
Recommendation for DR
Based on the evidence, apixaban is the most appropriate oral antithrombotic therapy for DR at this time. This is because apixaban has been shown to be effective in preventing stroke and systemic embolism, while also having a lower risk of major bleeding compared to other oral anticoagulants 6, 4, 5. Direct oral anticoagulants, such as apixaban, have transformed the landscape of antithrombotic therapy and are generally preferred over warfarin for many patients with atrial fibrillation or venous thromboembolism 7.