Thrombolysis in Polycythemia Vera-Related Acute Ischemic Stroke
Direct Answer
There are no specific guidelines addressing thrombolysis in polycythemia vera (PV)-related acute ischemic stroke, but standard IV tPA protocols should be applied if patients meet eligibility criteria and have no absolute contraindications, with particular attention to platelet count, hematocrit control, and bleeding risk. 1
Standard Thrombolysis Guidelines Apply
The American College of Chest Physicians provides clear time-based recommendations that do not exclude PV patients:
Strongly recommend IV r-tPA (0.9 mg/kg, maximum 90 mg) within 3 hours of symptom onset (Grade 1A evidence), which results in 154 more favorable events per 1,000 patients treated 1, 2, 3
Suggest IV r-tPA for patients presenting between 3-4.5 hours from symptom onset (Grade 2C evidence), with 69 more favorable events per 1,000 patients 1, 3
Do not administer IV r-tPA beyond 4.5 hours from symptom onset (Grade 1B evidence) 1
Critical PV-Specific Considerations
Hematocrit Management
- PV patients should have hematocrit controlled below 45% through phlebotomy as standard disease management, which reduces thrombotic risk 4
- Elevated hematocrit is not listed as an absolute contraindication to tPA in standard guidelines, but optimal control prior to stroke reduces baseline thrombotic risk 4
Platelet Count Assessment
- Thrombocytopenia (platelet count <100,000/mm³) is traditionally considered an absolute contraindication to IV thrombolysis 5
- However, PV typically presents with thrombocytosis rather than thrombocytopenia 4
- Extreme thrombocytosis itself is not an absolute contraindication, though it increases baseline thrombotic risk 4
Aspirin Use Considerations
- Prior aspirin use increases the risk of severe hemorrhagic transformation (HT) in patients receiving tPA, particularly in older patients 6
- All PV patients should be on aspirin 81 mg once or twice daily as standard therapy unless contraindicated 4
- This creates a clinical dilemma: aspirin is essential for PV management but increases tPA-related bleeding risk 4, 6
- Despite increased bleeding risk, aspirin use is not an absolute contraindication to tPA 6
Risk Stratification for Hemorrhagic Transformation
Key risk factors for severe HT in tPA-treated patients include:
- Extent of parenchymal hypoattenuation on baseline CT (strongest predictor) 6
- Increasing age (particularly >60 years) 6
- Congestive heart failure 6
- Elevated baseline systolic blood pressure 6
- Prior aspirin use (which applies to most PV patients) 6
Alternative Reperfusion Strategies
If IV tPA is contraindicated or patient presents outside the standard window:
Consider intraarterial tPA within 6 hours for proximal cerebral artery occlusions in patients who don't meet IV tPA eligibility (Grade 2C) 1, 2
Mechanical thrombectomy may be considered in carefully selected patients who value uncertain benefits over risks (Grade 2C), though generally not recommended 1, 3
Post-Thrombolysis Management
Administer aspirin 160-325 mg within 48 hours of stroke onset (Grade 1A), which aligns with PV management requiring aspirin therapy 1, 2, 7
Use prophylactic-dose LMWH over unfractionated heparin for VTE prophylaxis in patients with restricted mobility (Grade 2B) 2, 3, 7
Common Pitfalls
Do not delay tPA administration to optimize hematocrit if patient presents within treatment window and meets eligibility criteria 2, 3
Do not withhold tPA solely based on PV diagnosis if standard eligibility criteria are met 1
Do not assume thrombocytopenia in PV patients—they typically have thrombocytosis, which is not a contraindication 4
Establish IV access in the non-paretic arm to preserve the affected limb for rehabilitation 2, 3