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

Objectives: 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.

Methods: 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).

Results: 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.

Conclusions: Aggregometry can help in predicting postoperative bleeding in double antiplatelet therapy patients undergoing coronary artery bypass grafting.