Preoperative detection and management of immune heparin-induced thrombocytopenia in patients undergoing heart surgery with iloprost

Objective: The objective of this study was to evaluate our protocol for the identification and management of patients with immune heparin-induced thrombocytopenia undergoing cardiac surgery. Methods: Among 1518 patients who underwent cardiac surgery between June 1998 and May 2001, 32 (2.1%) presented with platelet counts less than 150,000/mm(3) preoperatively or a history of prolonged (>3 days) intravenous exposure to heparin or both. These 32 patients were evaluated with an enzyme-linked immunosorbent assay for antibodies against heparin-platelet factor 4 complex. Platelets of patients with detected antibodies were tested with the prostacyclin analog iloprost for inhibition of heparin aggregation and determination of the inhibiting concentration and corresponding intravenous infusion rate of iloprost. Patients with antibodies received heparin after complete platelet inhibition with iloprost infusion. Hypotension was prevented or treated with intravenous noradrenaline. Ten randomly selected patients with similar preoperative characteristics, no previous extended exposure to heparin, and normal platelet counts served as controls. Results: Ten of the 32 patients (group A, 31.3%) and none of the controls had antibodies against heparin-platelet factor 4 complex. Patients in group A underwent surgery with iloprost (6-24 ng (.) kg(-1) (.) min(-1)) and had their blood pressure maintained at greater than 95 mm Hg with norepinephrine infusion (1-4 mug kg(-1 .) min(-1)). Operative mortality was zero. There were no thrombotic complications or bleeding requiring exploration. One patient in group A bled 1310 mL/6 hours but did not need exploration. There was no difference in postoperative blood loss and morbidity between groups. Platelet counts were reduced by 12.5% +/- 8.7% (group A) and 38.1% +/- 15.2% (control) (P < .001) 1 hour postoperatively and reached preoperative values by the fifth postoperative day. Conclusions: Immune heparin-induced thrombocytopenia can be detected preoperatively among patients with a low platelet count or a history of prolonged heparin exposure or both. Cardiac surgery can be safely undertaken using iloprost-induced platelet inhibition during heparinization.