Divisions of Cardiac Surgery. Electronic address: firstname.lastname@example.org Divisions of Cardiac Surgery. Departments of Anesthesia; Critical Care and Medicine, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada. Department of Anesthesia & Perioperative Medicine, MEDICI Centre, University of Western Ontario. Critical Care and Medicine, St Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
BACKGROUND Blood transfusion is a well-established independent risk factor for mortality in patients undergoing cardiac surgery but the impact of platelet transfusion is less clear. We performed a systematic review and meta-analysis of observational studies comparing outcomes of patients who received platelet transfusion following cardiac surgery. METHODS We searched MEDLINE and EMBASE databases to January 2019 for studies comparing peri-operative
outcomes in patients undergoing cardiac surgery with and without platelet transfusion. RESULTS There were 9 observational studies reporting on 101,511 patients: 12% with and 88% without platelet transfusion. In unmatched/unadjusted studies, patients who received platelet transfusion were older with greater incidence of renal, peripheral and cerebrovascular disease, myocardial infarction, left ventricular dysfunction, and anemia. They were more likely to have non-elective, combined surgery; pre-operative hemodynamic instability and endocarditis; and more likely to be on clopidogrel preoperatively. Perioperative complications were significantly increased without adjusting for these baseline differences. After pooling only matched/adjusted data, differences were not found in patients who did vs did not receive platelets for operative mortality (risk ratio [RR] 1.26, 95%CI:0.69-2.32, p=0.46, 5 studies), stroke (RR 0.94, 95%CI:0.62-1.45, p=0.79, 5 studies), myocardial infarction (RR1.29, 95%CI:0.95-1.77, p=0.11, 3 studies), reoperation for bleeding (RR1.20, 95%CI:0.46-3.18, p=0.71, 3 studies), infection (RR1.02, 95%CI:0.86-1.20, p=0.85, 6 studies), and peri-operative dialysis (RR0.91, 95%CI:0.63-1.32, p=0.62, 3 studies). CONCLUSIONS After accounting for baseline differences, platelet transfusion was not linked with perioperative complications in cardiac surgery patients. Given the small number of observational studies, these findings should be considered hypothesis generating.