Clinical Pathology Abstracts, 8/16

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Cold antibodies in cardiovascular surgery: Is preoperative screening necessary?

Cold antibodies may be detected with routine pretransfusion testing and may obscure the identification of clinically significant red blood cell antibodies. They may be detected in healthy people or may be transient in appearance after a mycoplasma or mononucleosis infection. In most cases, cold antibodies are benign, and pretransfusion laboratory testing is designed to avoid detecting these antibodies by eliminating testing at room temperature. However, some cold antibodies may be pathogenic, and these are associated with hemolytic anemia or microvascular occlusion on exposure to the cold, or both. Whether the antibodies are benign or pathogenic, there is concern that they can negatively affect hypothermic conditions in cardiovascular surgery. The authors conducted a retrospective study in which they reviewed the records of patients with cold antibodies who underwent cardiovascular surgery to determine the incidence of intraoperative complications due to the antibodies. They studied the records of 99 of 47,373 patients who underwent cardiovascular surgery and had a history of cold antibodies before or within 30 days of surgery. Of interest, two of these cases were not reported to the transfusion service. The remaining 97 patients underwent hypothermic surgery, and intraoperative agglutination was noted in four. The frequency of intraoperative agglutination was calculated at only four percent among patients with cold antibodies. There were no reports of hemolysis. The authors concluded that the risk of cold antibodies-associated complications in cardiovascular surgery is low and can be managed by preoperatively assessing the clinical evidence of cold agglutinin disease and through careful monitoring during surgery. The authors noted that the data do not justify specialized testing protocols to preoperatively screen for these antibodies. However, if an incidental cold antibody is causing an incompatible crossmatch, antigen-negative units should be selected, if feasible, to avoid intraoperative hemolysis.

Sapatnekar S, Figueroa PI. Cold antibodies in cardiovascular surgery: Is preoperative screening necessary? Am J Clin Pathol. 2016;145:789–795.

Correspondence: Dr. Suneeti Sapatnekar at sapatns@ccf.org

Platelet transfusion vs. standard care to reduce intracerebral hemorrhage growth

Spontaneous intracerebral hemorrhage accounts for two-thirds of hemorrhagic stroke and may be associated with antiplatelet therapy. One study showed that people taking antiplatelet therapy have a 27 percent increased odds of death after intracerebral hemorrhage compared to those not taking antithrombotic drugs. Platelet transfusion is often used prophylactically to prevent acute intracerebral hemorrhage. Observational studies have reported variable associations with outcome after platelet transfusion for acute intracerebral hemorrhage in people taking antiplatelet therapy. A lack of randomized trials has prevented the generation of guidelines that recommend platelet use in these patients. The authors conducted a randomized control trial of platelet transfusion in patients with acute intracerebral hemorrhage associated with use of antiplatelet therapy. They performed a multicenter, randomized, open-label, parallel-group trial (PATCH trial) at 36 hospitals in the Netherlands, 13 hospitals in the United Kingdom, and 11 hospitals in France. The central aim of the study was to determine if platelet transfusion, compared with standard care, would reduce death or dependence by reducing intracerebral hemorrhage growth. Adults were enrolled in the study within six hours of a supratentorial intracerebral hemorrhage if they had used antiplatelet therapy for at least seven days beforehand and had a Glasgow Coma Scale of at least eight. Patients were assigned in a 1:1 ratio to receive either standard care or platelet transfusion plus standard care. The results showed that the odds of death or dependence at three months were higher in the platelet transfusion group than in the standard care group. Moreover, 42 percent of participants who received platelet transfusions had a serious adverse event during their hospital stay compared to 29 percent who received standard care. The authors concluded that platelet transfusion appeared inferior to standard care for people taking antiplatelet therapy before an intracerebral hemorrhage. Due to the findings from the PATCH trial, platelet transfusion cannot be recommended for the treatment of acute intracerebral hemorrhage in people taking antiplatelet therapy.

Baharoglu MI, Cordonnier C, Al-Shahi Salman R, et al. Platelet transfusion versus standard care after acute stroke due to spontaneous cerebral haemorrhage associated with antiplatelet therapy (PATCH): a randomised, open-label, phase 3 trial. Lancet. 2016;387:2605–2613.

Correspondence: Yvo B. Roos at y.b.roos@amc.uva.nl