Abstract 10331: Aspirin Responsiveness Testing Predicts Bleeding During Coronary Artery Bypass Grafting: The Verify Pre-Op - TIMI 45 Study
Introduction: Many patients receive aspirin prior to coronary artery bypass grafting (CABG), despite its association with perioperative bleeding and variable effectiveness among individuals.
Hypothesis: We assessed the hypothesis that point-of-care aspirin responsiveness testing predicts bleeding and ischemic events during CABG.
Methods: Verify Pre-Op [[Unable to Display Character: –]] TIMI 45 was a prospective study of 38 patients on aspirin who underwent CABG. VerifyNow™ Aspirin Reaction Units (ARU) (Accumetrics, San Diego, CA) were measured < 24 hours before CABG, with higher ARU indicating more reactive platelets. Endpoints were decrease in hemoglobin (Hgb) and hematocrit (HCT), platelet transfusion, major bleeding (≥ 5 red blood cell units transfused or > 2 L chest tube output), and myocardial infarction < 24 hours after surgery. Endpoints were analyzed by ARU tertiles, and the cut-point for the lowest tertile (ARU 412), reported as mean ± SD.
Results: Mean ARU was 472 ± 85. There was less bleeding across tertiles of higher ARU (p=0.039 for Hgb; p=0.028 for HCT) (Figure). Decrease in Hgb was greater in patients with ARU < 412 (5.4 ± 2.3 g/dL v. 3.4 ± 2.0 g/dL, p=0.011). Decrease in HCT was also greater in those with ARU < 412 (16.3 ± 6.9% v. 10.2 ± 6.2%, p=0.008). As a continuous variable, higher platelet reactivity (ARU) correlated with less of a decrease in Hgb and HCT (Spearman r=0.422, p=0.008 for Hgb; r=0.426, p=0.008 for HCT). Patients with ARU < 412 were more likely to have at least one platelet transfusion (53.9% v. 8.7%, p=0.005), and more units transfused (2.3 ± 3.8 units v. 0.2 ± 0.6 units, p=0.003). Major bleeding was more frequent in those with ARU < 412 (25% v. 0%, p=0.026). There was no difference in myocardial infarction, though there were few events (n=3).
Conclusion: Aspirin responsiveness testing predicts bleeding in patients exposed to aspirin undergoing CABG. An ARU ≥ 412 was predictive of less bleeding, less need for platelet transfusion, and was not associated with increased ischemic risk.
- © 2013 by American Heart Association, Inc.