Patients with active bleeding and a low platelet count (<50,000/microL) or platelet dysfunction (eg, chronic aspirin therapy; or clopidogrel). If the patient is taking the medications because of a recent (less than one year) vascular stent placement or acute coronary syndrome, when possible, a cardiologist should be consulted prior to stopping the agent or giving a platelet transfusion.
Two methods of pathogen reduction80,81 have been evaluated in clinical trials. Both systems involve adding an agent—either amotosalen (Intercept system)80 or riboflavin(Mirasol system)81—to the platelets prior to exposure to ultraviolet (UV) light. After UV exposure, these agents prevent replication of RNA and DNA in pathogenic organisms, as well as eliminating the function of contaminating leukocytes.82,83 Both the Mirasol and Intercept methods produce a reduction in posttransfusion autologous radiolabeled platelet recoveries and survivals84,85 that is related to the dose of UV used in the pathogen-reduction process.86 Recoveries and survivals of 5-day stored pathogen-treated platelets were reduced by approximately 15 to 25 percent, compared to similarly stored nontreated platelets from the same subjects (p <0.05 to <0.01). The Intercept system has been evaluated in a 645-patient U.S. randomized trial comparing treated to control platelets.87This technology was approved by the FDA for pathogen reduction of platelet components on December 19, 2014. A limited randomized trial in France involving 110 thrombocytopenic patients documented hemostatic efficacy of Mirasol-treated platelets and similar rates of red cell and platelet utilization but lower CCIs for patients who received treated compared to control platelets.88 However, there were no adverse events following transfusion of the treated platelets, and more studies will likely be needed for FDA approval. Both technologies have received regulatory approval for their use in Europe.
Several centers in Europe that have incorporated pathogen reduction technology have eliminated γ-irradiation of platelets to prevent transfusion-associated GVHD. Inactivating leukocytes may also decrease transfusion-related adverse events such as fever, chills, and allergic reactions associated with cytokine release from residual white cells during platelet storage, and it may also reduce rates of platelet alloimmunization. All of these benefits will mean safer, more cost-effective platelets for transfusion.