Key result
Unopposed warfarin dose escalation precipitates acute femoral DVT during therapy initiation for AF.
Case Report (n=1)
No
Prematurely escalating an unopposed warfarin slow-start regimen from 2 mg to 5 mg daily without heparin bridging can acutely deplete protein C and S and precipitate paradoxical deep vein thrombosis.
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Alerts clinicians to bridging needs during warfarin initiation in AF; hypothesis-generating for protein C/S depletion causing paradoxical DVT.
We are presenting a 72-year-old female who was admitted to hospital with deep vein thrombosis (DVT). She was known to have atrial fibrillation and was initiated on warfarin for stroke prophylaxis 3 days earlier. She was given warfarin therapy without low molecular weight heparin cover as per “slow-start regimen” protocol. The warfarin dose was increased after 3 days to achieve rapid anticoagulation, resulting in DVT in the left leg. We propose that the higher unopposed warfarin dose utilized in this case resulted in DVT. Warfarin loading doses may paradoxically result in a hypercoagulable state and potential clot formation because of significant reductions in protein C and protein S levels.
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Binymin et al. (2014) conducted a case report in Persistent nonvalvular atrial fibrillation complicated by warfarin-induced deep vein thrombosis (n=1). Warfarin was evaluated on Left femoral deep vein thrombosis (DVT). Unopposed warfarin loading escalated from to daily precipitated left femoral DVT (Naranjo score +2) with protein C at 13% and protein S at 28% in a 72-year-old woman with AF.
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