Comparison of bovine and porcine heparin in heparin antibody formation after cardiac surgery.
BACKGROUND
Heparin-induced thrombocytopenia (HIT) is a potentially devastating complication of heparin therapy. The incidence of clinical HIT after cardiovascular surgery is less than 2%, although asymptomatic antibodies to heparin-platelet factor 4 (PF4) occur more frequently. Bovine heparin is thought to cause more HIT than porcine heparin, although this has never been established for heparin use during coronary artery bypass grafting. We therefore undertook a randomized, prospective study of heparin-PF4 antibody formation in patients undergoing first-time CABG given intraoperative bovine or porcine heparin.


METHODS
Two hundred seven patients (108 porcine, 99 bovine) completed the study. Heparin given pre- or postoperatively was always porcine. Platelet counts and heparin-PF4 antibody tests (enzyme-linked immunosorbent assays) were performed preoperatively and daily until postoperative day 7 or discharge if earlier.


RESULTS
The overall incidence of heparin-PF4 antibody formation was 42%. Six patients (2.9%) were positive preoperatively, of which, 1 developed clinical HIT. When these were excluded, seroconversion rates were 44 of 99 (44.4%) and 33 of 108 (30.6%) for bovine and porcine heparin, respectively (p = 0.041). Among patients who produced antibodies, most (90% bovine, 85% porcine) seroconverted after postoperative day 2. There were no differences in postoperative platelet counts; only 1 patient developed thrombosis associated with seroconversion, but without developing thrombocytopenia. The seroconversion rates for patients having cardiopulmonary bypass or off-pump surgery were not significantly different.


CONCLUSIONS
This study confirms the high frequency of heparin-PF4 antibodies after coronary artery bypass grafting and demonstrates a significantly higher incidence after bovine heparin. However, because some patients may seroconvert after discharge, our study may underestimate the true incidence.
Francis
John L
JL
Center for Hemostasis and Thrombosis, Department of Thoracic Cardiovascular Surgery, Florida Hospital, 2501 N. Orange Ave, Suite 786, Orlando, FL 32804, USA. john.francis@flhosp.org
Palmer
George J
GJ
Moroose
Rebecca
R
Drexler
Alane
A
D000818:Animals; D000917:Antibody Formation / Q000502:physiology*; D006348:Cardiac Surgical Procedures; D002417:Cattle; D001026:Coronary Artery Bypass; D004797:Enzyme-Linked Immunosorbent Assay; D006493:Heparin / Q000009:adverse effects / Q000276:immunology*; D006801:Humans; D010976:Platelet Count; D010978:Platelet Factor 4 / Q000276:immunology; D011183:Postoperative Complications; D011446:Prospective Studies; D013552:Swine; D013921:Thrombocytopenia / Q000139:chemically induced / Q000276:immunology
D010978:Platelet Factor 4; D006493:Heparin