Final Recommendations

In patients with a history of HIT and a negative antibody test result at time of surgery, anticoagulation during surgery should be performed with UFH (Fig. 1). Postoperatively, if further anticoagulation is needed, an alternative non-heparin anticoagulant should be given. In patients with detectable antibodies, the operation should be postponed whenever possible to allow for disappearance of the antibodies (40-100 days). Surgery is likely also safe if the antibodies are of the (non-platelet-activating) IgA and/or IgM classes, or if the IgG antibodies are "weak" (i.e., negative testing in the platelet serotonin release assay) and have gray zone results in the enzyme immunoassay. It is reasonable to repeat testing for HIT antibodies at short intervals (e.g., every 2 or 3 wk), as antibodies can disappear quickly in some patients. Thereafter, surgery is performed with UFH, as above.

In patients with a positive antibody test before surgery requiring urgent operation, an alternative approach should be used. Based on current data, bivalir-udin appears to be the first-line strategy for OPCAB surgery, and for a large variety of standard CPB procedures (CABG, isolated valve surgery, combined CABG and valve procedures). However, consideration should be given to the modifications of CPB and surgical practice that are necessary due to the pharmacology of bivalirudin (Table 3). Lepirudin should only be used in patients with normal renal function and a low probability of developing perioperative renal impairment. Moreover, point-of-care monitoring with the ECT is a further obligation for use of lepirudin in this indication. The heparinoid, danaparoid, cannot be recommended for CPB procedures but might be an option in OPCAB and peripheral vascular surgery.

In complex procedures or institutions with minor experience in alternative anticoagulation strategies, risk reduction might be achieved best by combination of UFH with a short-acting potent antiplatelet agent in order to attenuate the HIT reaction. The safest class of agents appears to be prostaglandins as the elimination half-life is very short, and major bleeding complications appear to be uncommon. However, their potent hypotensive effect should be considered. The short-acting platelet GPIIb/IIIa antagonist tirofiban may also be used for this purpose, if there is a low probability that the patient will develop perioperative renal failure.

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