Postoperative bleeding in coronary artery bypass patients on double antiplatelet therapy: predictive value of preoperative aggregometry.

Abstract

We tested the possible value of routine aggregometry testing for bleeding prediction following coronary artery bypass grafting in patients who received preoperative double antiplatelet therapy. In 226 patients undergoing on-pump isolated coronary artery bypass grafting, aggregometry [adenosine diphosphate (ADP) test and ASPI test] was always prospectively performed by Multiplate® analyser immediately before surgery. We assessed the differences in postoperative bleeding according to the type of double antiplatelet therapy [acetylsalicylic acid plus clopidogrel (ASA+C), or plus ticagrelor (ASA+T)], duration of clopidogrel/ticagrelor withdrawal (0-3 days or ≥ 4 days) and results of aggregometry tests. Multivariable predictors of blood losses were sought by linear regressions (drainage amount at 6, 12 and 24 postoperative hours) and logistic regression (increased bleeding: 75th percentile of blood losses at 6 h, i.e. >450 ml). Overall, postoperative blood losses did not significantly differ between treatment groups (median at 6 h: ASA + C = 335 ml, ASA + T = 300 ml, P = 0.21). With longer withdrawal interval, higher rates of patients with normal ADP-related platelet function were observed in both groups (ASA + C: P = 0.04; ASA + T: P = 0.006) but only in the ASA + T group were blood losses significantly smaller at all 3 time points. Bleeders (>450 ml at 6 h) were significantly less frequent among patients with ADP test showing recovered platelet function (ASA + T: P = 0.002; ASA + C: P = 0.053). The correlation between ADP test result and blood losses amount was stronger in the ASA + T group (e.g. at 6 h: r = -0.6; P < 0.001). In multivariable analyses, the ADP test result independently predicted postoperative bleeding in the ASA + T group and the ASPI test in the ASA + C group. Aggregometry can help in predicting postoperative bleeding in double antiplatelet therapy patients undergoing coronary artery bypass grafting.