Warfarin Initiation in Cerebral Venous Thrombosis
In patients with cerebral venous thrombosis (CVT), warfarin should be started early (same day) alongside parenteral anticoagulation and continued for a minimum of 5 days with parenteral therapy until the INR is ≥2.0 for at least 24 hours. 1
Initial Anticoagulation Approach
- Patients with CVT should first receive parenteral anticoagulation (LMWH, fondaparinux, IV UFH, or subcutaneous UFH) before transitioning to warfarin 1
- Anticoagulation should be started immediately after the diagnosis of CVT, even if intracranial hemorrhage is present 1
- For warfarin initiation, early initiation (same day as parenteral therapy) is recommended over delayed initiation 1
Warfarin Dosing and Monitoring
- When starting warfarin, a lower initial dose of 5 mg is preferred in older patients (>60 years) and those at higher risk of bleeding 1
- A starting dose of 10 mg may be considered in younger (<60 years), otherwise healthy patients 1
- Parenteral anticoagulation must be continued for a minimum of 5 days AND until the INR is ≥2.0 for at least 24 hours 1
- The target therapeutic INR range should be 2.0-3.0 (target INR 2.5) 1
Duration of Therapy
- A minimum 3-month treatment phase of anticoagulation is recommended for patients with CVT 1
- For patients with unprovoked CVT or CVT provoked by persistent risk factors, extended anticoagulation therapy should be considered 1
- In patients with CVT associated with a major transient risk factor, extended anticoagulation beyond the initial 3 months is not recommended 1
Special Considerations
- For patients with CVT and active cancer who do not have high bleeding risk, extended anticoagulant therapy with no scheduled stop date is recommended 1
- Recent evidence suggests that direct oral anticoagulants (DOACs) like dabigatran may be as safe and effective as warfarin for CVT, though warfarin remains standard therapy 2
- In patients with severe renal dysfunction (creatinine clearance <30 mL/min), unfractionated heparin is preferred for initial parenteral anticoagulation before warfarin initiation 1
Monitoring and Follow-up
- During transition to warfarin monotherapy, the INR should be measured at least twice weekly initially 1
- Once the patient is on warfarin monotherapy, INR should be monitored at least weekly initially 1
- Monitor for signs of recurrent thrombosis or bleeding complications during follow-up 2
Potential Pitfalls
- Delaying warfarin initiation unnecessarily extends the duration of parenteral therapy required 1
- Starting with excessively high warfarin doses increases the risk of bleeding complications 1, 3
- Discontinuing parenteral anticoagulation before achieving a therapeutic INR for at least 24 hours increases risk of thrombosis progression 1
- Failure to consider patient-specific factors (age, renal function, bleeding risk) when selecting initial warfarin dose 1