Heparin antibodies and thromboembolism in heparin-coated and noncoated ventricular assist devices

Objective: Coating of ventricular assist devices (VADs) with heparin improves the biocompatibility and may reduce the need for systemic anticoagulation. However, heparins are associated with the risk of formation of heparin/platelet factor 4 antibodies (HPF4/A) and the development of heparin-associated thromboemboli. We analyzed the occurrence of HPF4/A and thromboembolism in patients with heparin-coated and noncoated VADs. Methods: One hundred patients were enrolled in the investigation. Fifty-seven received a heparin-coated (group 1) and 43 a noncoated (group 2) VAD. HPF4/A testing was performed before and 2 and 12 weeks after implantation by the heparin platelet factor 4 enzyme-linked immunosorbent assay. Results: There was no significant difference in the occurrence of HPF4/A in the 2 groups (P = .102). Before the operation, 21 of the patients in group 1 had positive test responses and 25 in group 2. No patient had HPF4/A after termination of systemic heparinization. In group 1 there was no significant difference in the incidence of recurrent pump thromboses in patients who had positive test responses for HPF4/A (n = 11) when compared with those who had negative test responses (n = 9, P = .89). Twenty-one patients had HPF/A but no thromboembolism. However, all 22 patients who had thromboembolism had HPF4/A. Conclusions: Heparin coating of the VAD surface does not enhance the occurrence of HPF4/A-associated immunologic or thrombogenic reactions. However, the presence of these antibodies is strongly associated with an increased risk of thromboembolism in patients with a VAD.