From the Guidelines
Anticoagulation therapy can be initiated after an ischemic stroke due to atrial fibrillation, with the timing depending on the stroke's severity and size, typically starting 3 days after minor strokes, 6-8 days after moderate strokes, and 12-14 days after severe strokes. The decision to initiate anticoagulation should balance the risk of recurrent stroke against the risk of hemorrhagic transformation, which is highest in the first few days after a stroke 1.
Key Considerations
- For minor strokes (NIHSS score <8), anticoagulation can typically begin 3 days after stroke onset, as the risk of recurrent stroke outweighs the risk of hemorrhagic transformation 1.
- For moderate strokes, waiting 6-8 days is recommended, as the risk of hemorrhagic transformation is higher, but the risk of recurrent stroke still necessitates anticoagulation 1.
- For severe strokes (large infarcts or hemorrhagic transformation), waiting 12-14 days before starting anticoagulation may be necessary to minimize the risk of hemorrhagic transformation 1.
Anticoagulant Options
- Common anticoagulants include direct oral anticoagulants (DOACs) such as apixaban (5mg twice daily), rivaroxaban (20mg daily), dabigatran (150mg twice daily), and edoxaban (60mg daily), or warfarin (dose adjusted to maintain INR 2-3) 1.
Monitoring and Maintenance
- Brain imaging should be performed before starting anticoagulation to rule out hemorrhagic transformation 1.
- Once anticoagulation is initiated, it should generally be continued indefinitely for patients with atrial fibrillation, as the stroke risk is ongoing 1.
- Regular monitoring for bleeding complications and medication adherence is essential for optimal stroke prevention 1.
From the Research
Timing of Anticoagulation Initiation
The optimal time to initiate anticoagulation therapy after an acute ischemic stroke in patients with atrial fibrillation (AFib) is uncertain. Several studies have investigated this topic:
- A study published in 2021 2 found that early initiation of anticoagulation after transient ischemic attack (TIA), small-, or medium-sized acute ischemic stroke (AIS) from AFib does not appear to compromise patient safety.
- Another study from 2020 3 reported that in patients with small AIS without hemorrhagic transformation, 51% of stroke neurologists elected to start anticoagulation within 96 hours.
- A review of the literature published in 2020 4 suggested that insufficient data exist to support the safety of routine oral anticoagulant initiation within 48 hours of an acute ischemic stroke.
- A more recent study from 2023 5 reported promising results of early direct oral anticoagulant (DOAC) initiation after acute ischemic stroke, but noted that larger randomized trials are ongoing.
- A retrospective cohort study from 2020 6 found that the median time to initiation of anticoagulation was 59.5 hours after stroke onset for those who did not receive thrombolytic therapy and 82.6 hours for those who did receive thrombolytic therapy.
Factors Influencing Anticoagulation Timing
Several factors may influence the timing of anticoagulation initiation, including:
- Infarct size and presence of hemorrhage 4
- Risk of recurrent ischemic stroke and hemorrhagic transformation 5
- Use of thrombolytic therapy 6
- Presence of left atrium/left atrial appendage or acute left ventricular thrombi, or mechanical heart valve 3
Anticoagulation Choice
The choice of anticoagulant may also be important:
- Direct oral anticoagulants (DOACs) were the preferred anticoagulation strategy in a survey of US stroke specialists 3
- Apixaban had statistically similar yet generally numerically lower rates of recurrent strokes/TIA, death, and symptomatic hemorrhages compared to warfarin in a randomized controlled trial 2