Appropriate platelet function determines both the perioperative haemostasis and the risk of postoperative thrombotic complications in patients undergoing branched endovascular repair (bEVAR) of thoracoabdominal aortic aneurysm (TAAA). We aimed to assess the effect of bEVAR on platelet function and the predictive value of preoperative platelet function for postoperative bleeding. We measured platelet function using impedance aggregometry and total thrombus-formation analysis system in 50 consecutive patients, with TAAA undergoing elective bEVAR. After bEVAR, platelet reactivity was assessed using ASPI test, ADP test and TRAP test and thrombus size decreased, whereas time to clot formation increased, compared to baseline (p ≤ .042 for all). Preoperative platelet reactivity in the TRAP test was lower in patients who experienced post-operative bleeding, defined as ≥3 red blood cell units transfusion, compared to those who did not (p = .038). Baseline hemoglobin level <13 g/dl and TRAP test result ≤29.5 AUC increased the odds of bleeding by 5.4-fold and 6.8-fold, respectively, independent of other clinical variables. We conclude that in patients with TAAA undergoing bEVAR, platelet reactivity and platelet-rich thrombus formation decreased directly after the operation. Preoperative hemoglobin level and platelet reactivity in the TRAP test were independent predictors of postoperative bleeding complications.
