Overview
This lecture reviews current evidence and guidelines regarding anticoagulation therapy after stroke, focusing on who should receive it, which agents are preferred, and optimal timing for initiation.
Stroke Etiology & Classification
- Strokes can be ischemic (blockage) or hemorrhagic (bleed).
- TOAST classification describes stroke causes: large artery atherosclerosis, small vessel occlusion, cardioembolic, other determined causes, and cryptogenic/ESUS.
- ESUS (Embolic Stroke of Undetermined Source) often remains after full workup, especially in younger patients.
Indications for Anticoagulation ("Who")
- Key indications: atrial fibrillation (AF), mechanical heart valves, left atrial/ventricular thrombus, antiphospholipid syndrome.
- Cervical artery dissection and ESUS are not clear indications based on current evidence.
- Reduced ejection fraction (<35%) alone is not sufficient unless a thrombus is present.
Pathophysiology & Thrombus Composition
- "Red thrombi" (fibrin-rich, low-pressure systems) respond better to anticoagulants.
- "White thrombi" (platelet-rich, high-pressure systems) respond better to antiplatelets.
- Thrombus composition studies inform therapy but direct clinical ties vary.
Special Stroke Subtypes
- Cervical artery dissection: studies show no advantage of anticoagulants over antiplatelets.
- ESUS: Large trials (NAVIGATE-ESUS, RE-SPECT ESUS) show no benefit of anticoagulation over aspirin without identified AF.
- Cardiac monitoring in ESUS may reveal AF, warranting anticoagulation if detected.
- Aortic atheroma/arterial plaques prefer antiplatelets; insufficient data for routine anticoagulant use.
- Patent foramen ovale (PFO): closure plus antiplatelets reduces recurrence in select young patients.
- Cancer-associated stroke: stroke risk is higher, but evidence for anticoagulation is not definitive.
Preferred Agents ("What")
- Warfarin and direct oral anticoagulants (DOACs/NOACs) are effective for AF, with DOACs showing lower intracranial hemorrhage risk.
- DOACs include dabigatran, rivaroxaban, apixaban, edoxaban.
- Warfarin remains effective but carries higher bleeding risk.
- DOACs preferred for most non-valvular AF patients.
Timing of Anticoagulation ("When")
- Early anticoagulation increases bleeding risk; timing depends on stroke size/severity.
- European guidelines: 1 day after TIA, 3 days after mild stroke, 6 days after moderate, 12 days after severe stroke.
- American Heart Association: anticoagulation reasonable within 4–14 days, individualized by infarct size and risk factors.
- Delayed initiation advised after hemorrhagic transformation or large infarcts.
- After intracerebral hemorrhage, reinitiate anticoagulation at least 4 (some suggest 6–8) weeks later.
Key Terms & Definitions
- ESUS — Embolic Stroke of Undetermined Source: non-lacunar stroke without a clear source after workup.
- DOACs/NOACs — Direct/Novel Oral Anticoagulants: new class of anticoagulants (e.g., apixaban, rivaroxaban).
- TOAST Classification — System dividing stroke causes into major categories.
Action Items / Next Steps
- Review current department protocols for post-stroke anticoagulation.
- Stay updated on ongoing clinical trial results (e.g., OPTIMAS, ELAN).
- Apply individualized risk assessment (stroke type/severity, imaging) when planning anticoagulation.
- Consult cardiology or neurology for complex or borderline cases.