BACKGROUND: Management of a chronic hypercoagulable state during the cytopenic phase of peripheral blood stem cell transplant (PBSCT) poses a significant clinical challenge. Anticoagulation in the presence of significant thrombocytopenia raises the risk of bleeding. However, withholding anticoagulation may increase the risk of thrombotic events. The purpose of this study was to evaluate the safety and efficacy of low dose thromboprophylaxis with low molecular weight heparin (LMWH) during the thrombocytopenic phase of PBSCT.

METHODS: We undertook a retrospective analysis of all patients who underwent an autologous PBSCT at our institution from 1998 to 2005 and identified patients that were on therapeutic anticoagulation prior to their admission for transplantation. Institutional review board approval was obtained for this study. Information regarding indication of PBSCT, age, gender, indication for anticoagulation, bleeding or thrombotic event during hospitalization including bleeding or clotting at the site of indwelling central venous catheter, nature of anticoagulation, time to platelet engraftment, and number of platelet transfusions were recorded. Patients at known high risk for thrombosis were maintained on therapeutic dosage of warferin or LMWH until platelet counts decreased to < 50,000/μ liter, at which time LMWH 40 milligram/day subcutaneously was administered. Platelet counts were maintained at > 20,000/μ liter with transfusion support as needed.

RESULTS: Eight of seventy evaluable patients were identified during the pre-transplant screening to be maintained on long term anticoagulation. Median age of these patients was 57 years (range: 38–67); Male: Female ratio 1:1; Indications for PBSCT were relapsed non-hodgkins lymphoma (n=2), multiple myeloma (n=5), acute myeloid leukemia (n=1). Indications for long term anticoagulation prior to PBSCT included: Upper extremity DVT (n=1), lower extremity DVT (n=5), pulmonary embolism (n=1), atrial fibrillation (n=1), superior sagital sinus thrombosis (n=1). Prior to transplant, therapeutic anticoagulation was maintained with warfarin (n=4) and LMWH (n=4). Median number of days with platelet counts < 20,000 = 3 (range 1–5); median number of platelet transfusions required = 3 (range 1–4); median number of days requiring LMWH = 8 (range 1–11); median number of days with platelet count < 50,000 = 6 (range 4–9). Median time to platelet transfusion independence was 11 days post stem cell infusion (range 8–15 days). One patient had an indwelling IVC filter at the time of transplantation. No clotting events were noted during and immediately post-transplantation. One patient developed microscopic hematuria and one patient developed macroscopic hematuria during the hospitalization which resolved spontaneously. No additional clinically significant bleeding complications were noted.

CONCLUSION: Patients on chronic anticoagulation therapy can be safely transplanted with PBSCs and maintained on prophylactic doses of LMWH during the phase of moderate thrombocytopenia (platelet count < 50,000) without any increased incidence of clotting or bleeding events.

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