Between Scylla and Charybdis: antithrombotic therapy in hematopoietic progenitor cell transplant patients

Patients who undergo hematopoietic progenitor cell transplant may require antithrombotic therapy for a variety of reasons--history of vascular events or developing new ones during therapy. For patients with arterial disease, use of antiplatelet therapy is based on acuity. For primary prevention of an arterial event, aspirin can be withheld at the start of transplant. On the other hand, in the face of a patient experiencing an acute myocardial infarction, aspirin should be given, no matter what the degree of thrombocytopenia is. Patients with cardiac 'hardware'-stents and mechanical valves-pose difficult issues because as higher risk patients (especially patients with recent implantation of a drug eluting stent) they require more aggressive anticoagulation, even in the face of severe thrombocytopenia. Anticoagulation with heparin is dependent on the platelet count with full dose recommended for a platelet count over 50 × 10(9)/L and prophylactic dosing with platelets in the 20-50 × 10(9)/L range. If the patient develops a distal venous thrombosis, then simple observation can be used, but more proximal thrombosis or pulmonary embolism requires consideration of anticoagulation. Central venous catheter thrombosis is best treated by line removal, as the risk of bleeding is high if the device is left in. The advent of new anticoagulants with minimal drug and food interactions may offer better choices for therapy for these difficult patients. This is also an area in which clinical trials would be helpful to clarify the treatment choices.