Is There a Best Technique to Decrease Blood Loss and Transfusion After Coronary Artery Bypass Grafting?

Pharmacologic Hemostasis by Preoperative Recovery of Coagulation

Potent preoperative anticoagulants and antiplatelet drugs frequently increase bleeding and transfusion significantly after CABG. Therefore, when clinically feasible, they should be discontinued preoperatively to allow for the recovery of the coagulation system (Class IIb recommendation; Level C evidence). The timing of discontinuation depends on the half-life of the particular agent and the possibility of reversibility. The exception to this principle is unfractionated heparin (UFH), which may be discontinued shortly before CABG or not at all.

The greater frequency of the use of direct oral anticoagulants over Vitamin K antagonists has further added to the bleeding risk in CABG patients. The direct thrombin inhibitor dabigatran is currently the only oral agent available in its class, whereas the oral Factor Xa inhibitors include drugs such as rivaroxaban, apixaban, edoxaban, and betrixaban. Given the increased risk for bleeding associated with these agents, current guideline recommendations are cessation of therapy 48 hours before surgery, including cardiac surgery. ^, Additional time may be warranted in patients with renal dysfunction. ^, Measurement of plasma levels via various assays is an option to determine whether bleeding risk is low before CABG; however, many of the current tests are not readily accessible at all centers. ^, Management of bleeding in patients on these oral anticoagulants has recently been reviewed in the 2020 ACC Expert Consensus Decision Pathway. Although reversal agents are available for bleeding related to dabigatran (idarucizumab) or oral Factor Xa inhibitors (andexanet alfa), their use in managing post-CABG bleeding warrants further investigation given the prothrombotic potential and associated risks to bypass grafts.

It is reasonable to stop low-intensity antiplatelet therapy (i.e., aspirin) preoperatively in elective patients without acute coronary syndromes to reduce blood loss and transfusion after CABG (Class IIa recommendation; Level A evidence). ^{, ,} In the setting of patients with acute coronary syndromes undergoing CABG, however, aspirin continuation throughout the perioperative period may have greater efficacy and benefit (reduced ischemic events) compared with bleeding risk, especially when aspirin doses are less than 100 mg per day (Class IIa recommendation; Level A evidence). ^, The negligible impact on bleeding was actually confirmed by a randomized controlled trial in 2100 patients undergoing CABG. Patients assigned to aspirin (100 mg) on the day of surgery versus placebo demonstrated no difference in 24-hour blood loss.

High-intensity platelet blockade with P2Y12 inhibitors such as clopidogrel may be associated with life-threatening bleeding after CABG. It is reasonable to discontinue this potent platelet blockade before elective surgery to limit blood loss and transfusion (Class I recommendation; Level B evidence). ^, If P2Y12 inhibitor therapy is paused preoperatively in a patient receiving a dual antiplatelet regimen, aspirin should be continued. The period of discontinuation of P2Y12 inhibitors is dependent on the properties of the drug, but a period of at least 5 days is recommended for clopidogrel and ticagrelor. ^, Nevertheless, based on the variability in response and resistance to common antiplatelet agents, the period of discontinuation may be as short as 3 days. ^, The use of point-of-care testing for platelet adenosine diphosphate (ADP) responsiveness may be reasonable for identifying nonresponders and those eligible for earlier CABG. Preoperative platelet function testing has indeed been shown to lead to earlier surgery in clopidogrel-treated patients compared with a time-based strategy. Nevertheless, strong evidence is lacking because there is no universal definition for acceptable platelet function and because of variability among tests. ^, As for prasugrel, the recommended time interval remains 7 days because of the longer offset time and greater incidence of bleeding noted in CABG patients. ^, In the presence of coronary stents, whether bare-metal or drug-eluting stents, early withdrawal of antiplatelet therapy can precipitate stent thrombosis. The options to maintain stent patency must be considered, including preoperative hospitalization to substitute thienopyridine therapy with short-acting intravenous (IV) platelet blockade. Cangrelor is a short-acting, IV P2Y12 inhibitor that has already shown maintenance of platelet inhibition when used as a bridging agent without a significant increase in operative bleeding compared with placebo. Similarly, bridging with cangrelor has been shown to be an effective option for preventing stent thrombosis in patients presenting for surgical procedures.