Does Platelet Reactivity Predict Bleeding in Patients Needing Urgent Coronary Artery Bypass Grafting During Dual Antiplatelet Therapy?

Background: Up to 15% of patients require coronary artery bypass grafting (CABG) during dual antiplatelet therapy. Available evidence suggests an association between platelet reactivity and CABG-related bleeding. However, platelet reactivity cutoffs for bleeding remain elusive. We sought to explore the association between platelet reactivity and bleeding.

Methods: Patients on aspirin and a P2Y receptor inhibitor within 48 hours before isolated CABG (n = 149) were enrolled in this prospective study. Blood was drawn 2 to 4 hours preoperatively and platelet reactivity assessed by light transmittance aggregometry (LTA), vasodilator-stimulated phosphoprotein (VASP) assay, Multiplate analyzer and Innovance PFA2Y. The primary endpoint was calculated red blood cell loss computed as follows: (blood volume × preoperative hematocrit × 0.91) - (blood volume × hematocrit × 0.91 on postoperative day 5) + (mL of transfused red blood cells × 0.59).

Results: Preoperative platelet reactivity was low [median (interquartile range): LTA: 20 (9-28)%; VASP-PRI: 39 (15-73)%; Multiplate adenosine phosphate test: 16 (12-22) U∗min]. Innovance PFA2Y ≥300 seconds, 72%. Median (IQR) red blood cell loss in patients in first the LTA tertile was 1,449 (1,020 to 1,754) mL compared with 1,107 (858 to 1,512) mL and 1,075 (811 to 1,269) mL in those in the second and third tertiles, respectively (p < 0.004). Bleeding Academic Research Consortium (BARC)-4 bleeding differed between tertiles (62% versus 46% versus 36%; p = 0.037). In a multivariable linear regression model, aspirin dose ≥300 mg, cardiopulmonary bypass time, EuroSCORE, and tertile distribution of platelet reactivity were significantly associated with red blood cell loss.

Conclusions: A gradual decrease in red blood cell loss and BARC-4 bleeding occurs with increasing platelet reactivity in patients on antiplatelet therapy undergoing CABG. Our findings support current guidelines to determine time of surgery based on an objective measurement of platelet function (Platelet Inhibition and Bleeding in Patients Undergoing Emergent Cardiac Surgery; clinicaltrials.gov NCT01468597).