New Blood Conservation Guidelines on Antiplatelet Therapy

Reed Miller

March 16, 2011

March 16, 2011 (Chicago, Illinois) — The new guidelines on blood conservation in surgery incorporate recent evidence on antiplatelet therapy while continuing to emphasize the importance of preoperative risk assessment [1].

The 2011 update to the Society of Thoracic Surgeons (STS) and the Society of Cardiovascular Anesthesiologists (SCA) blood conservation clinical practice guidelines, published in the March 2011 issue of the Annals of Thoracic Surgery, include significant changes to the societies' first set of blood conservation recommendations in 2007.

"Not all patients undergoing cardiac procedures have equal risk of bleeding or blood transfusion. An important part of blood resource management is recognition of patients' risk of bleeding and subsequent blood transfusion," the writing committee, led by Dr Victor Ferraris (University of Kentucky, Lexington), explains in the document. "There is almost no evidence in the literature to stratify blood conservation interventions by patient risk category. Nonetheless, logic suggests that patients at highest risk for bleeding are most likely to benefit from the most aggressive blood management practices."

"A small fraction of the patients account for most of the blood transfusion, so there's unquestionably a high-risk group," and the guidelines are primarily aimed at managing that group, Ferraris told heartwire .

An important component of preoperative risk assessment identified in the new guidelines but not addressed in the 2007 version is the identification and management of preoperative antiplatelet drug therapy. "Persistent evidence supports the discontinuation of drugs that inhibit the P2Y12 platelet binding site before operation, but there is wide variability in patient response to drug dosage (especially with clopidogrel)," the guidelines authors explain. "Newer P2Y12 inhibitors are more potent than clopidogrel and differ in their pharmacodynamic properties. Point-of-care testing may help identify patients with incomplete drug response who can safely undergo urgent operations."

New STS/SCA Recommendations on Preoperative Interventions for Blood Conservation

Recommendation Class of recommendation Level of evidence
P2Y12-receptor inhibitors should be discontinued before operative coronary revascularization (either on pump or off pump), if possible. The optimum time between drug discontinuation and operation will vary depending on the drug. 1 B
Point-of-care testing for platelet ADP responsiveness might be reasonable to identify clopidogrel nonresponders. IIb C
Adding a P2Y12 inhibitor to aspirin therapy soon after CABG surgery may increase the risk of reexploration and subsequent operation. III B
Preoperative erythropoietin (EPO) plus iron given several days before cardiac operation is a reasonable approach to increasing red-cell mass in patients with preoperative anemia, in candidates for operation who refuse transfusion, or patients at high risk for postoperative anemia. Chronic EPO may cause thrombotic cardiovascular events in renal-failure patients. IIa B
Recombinant human EPO may be considered to restore red-blood-cell volume in patients also undergoing autologous preoperative blood donation before cardiac procedures, but this approach has not been evaluated in large studies. IIb A


Ferraris acknowledged that the most current evidence on antiplatelet therapy is always "a moving target. There are new drugs and new evidence, and some of the new things aren't even on the market yet but probably will be [soon]," he said. So the next iteration of these guidelines will no doubt include even more new evidence on antiplatelet drugs and how to use them. For example, Ferraris noted that recently published data suggest that chronic aspirin therapy can be discontinued earlier than five days before coronary bypass surgery without increasing the risk of MI, death, or stroke.

"But one consistent finding is that antiplatelet drugs cause excess bleeding, and that hasn't changed with the new drugs," Ferraris told heartwire . "The only thing that changes is the pharmacodynamics. Some of the newer drugs have a shorter half-life, and you don't have to wait as long to do an operation after you stop those newer drugs, and that's a change for the better."

Other additions to the guidelines that Ferraris highlighted are the recommendations on topical hemostatic agents used during surgery to mitigate bleeding. "There's a whole bunch of these things [on the market], with surprisingly little evidence to support their use, but they're widely used," Ferraris said. Topical hemostatic agents that employ localized compression get a IIb recommendation (evidence level C) while antifibrinolytic agents used to limit chest tube drainage get a IIa rating (evidence level B).

Also, the new guidelines recommend against using aprotinin (Trasylol, Bayer Healthcare Pharmaceuticals), an antifibrinolytic agent, to reduce bleeding after cardiac surgery. Bayer took the drug off the market after it was shown that its risk outweighed its potential benefits.

Better Format Needed for Guidelines

Ferraris said that the writing committee is also working on finding a better way to disseminate these guidelines and teach physicians about them beyond just publishing them in a journal. "We'd like to find a forum that isn't so cumbersome." For example, the STS and SCA may develop an iPhone application or a set of flash cards to help users learn the guidelines more easily. "One of the benefits of the guidelines is that you find out where there is a lack of evidence or gaps in the knowledge base, so guidelines serve to generate hypotheses about what needs to be done next. So somehow we need to figure out how to disseminate these more widely."


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