Abstract This case series describes the use of four factor prothrombin complex concentrate (4FPCC) to reverse warfarin anticoagulation without the need for pre-procedure bridging with a parenteral agent or the use of FFP or vitamin K in patients with ventricular assist devices (VAD) who require invasive procedures. Patients were included if they had a history of recent warfarin use and documentation of temporary warfarin reversal for the procedure. Patients were excluded if their first dose of 4FPCC was for active bleeding. INR was assessed prior to 4FPCC administration, and trended for at least 90 h afterwards. Charts were reviewed for adverse events. In patients who received only 4FPCC for INR correction, the mean INR before 4FPCC was given was 2.7 (SD 0.64), which dropped an average of 35.4% after administration to a mean INR of 1.6 (SD 0.30). In the two patients who also received vitamin K, the average INR before reversal was 2.0 (SD 0.49), and was reduced by 35.9% to 1.3 (SD 0.21). The average number of days until patients re-established a therapeutic INR with 4FPCC alone was 3.2 days post procedure compared to 8.5 days for patients who received concomitant vitamin K. No bleeding or thrombotic events were observed. Using 4FPCC without vitamin K may provide VAD patients and clinicians with safe, effective, and rapid reversal of warfarin with faster recovery to the target INR following the procedure.
Keywords: ventricular assist device; VADs; anticoagulation reversal; prothrombin complex concentrates; INR; warfarin reversal

Abstract Myeloproliferative neoplasms (MPN) – polycythaemia vera (PV) and essential thrombocythaemia (ET) are common causes of abdominal vein thrombosis (portal and hepatic veins). The JAK2 mutation is found in 50% of ET and 95% of cases of PV and should be a standard investigation for all cases of abdominal vein thrombosis. Two cases are presented of portal vein thrombosis due to underlying ET with normal or near normal platelet counts. There was a long delay in diagnosing the MPN in these two cases when relying on the current diagnostic criteria. These diagnostic classifications tend to miss cases of early or latent cases of ET, particularly those that are JAK2 negative. In JAK2 negative cases, diagnosis depends on marrow histology which is often unreliable. Moreover, the thrombotic risk is independent of the platelet count in ET and can occur even in ET with normal or mildly elevated platelets. Awareness of these possible scenarios can avoid debilitating thrombosis by the early institution of antiplatelet therapy.
Keywords: abdominal vein thrombosis; myeloproliferative disease; essential thrombocythaemia