Three patients scheduled for heart transplantation with end-stage heart failure complicated by subacute heparin-induced thrombocytopenia (HIT). In all 3 patients, heart transplantation was successfully performed using short-term unfractionated heparin (UFH) during transplantation despite a positive anti-PF4/heparin IgG by enzyme-immunoassay (EIA). Results of the EIA test are represented by black vertical bars; results of the heparin-induced platelet-activating (HIPA) test are given as text; platelet count courses are represented by lines. The gray shaded area represents standard deviation (plus or minus) of mean platelet counts of 10 consecutive non-HIT patients after heart transplantation. The clinical course and laboratory test results (obtained from another hospital in patients 2 and 3) are given at the left hand side of the figure. Criteria to diagnose HIT in patient 1 were platelet decrease greater than 50% after 9 days of heparin treatment, positive anti-PF4/heparin IgG, positive HIPA, and rapid increase of platelet count after switching from heparin to argatroban. Criteria to diagnose HIT in patient 2 were platelet decrease greater than 50% after 7 days of heparin treatment, complicated by iliac artery embolism, positive anti-PF4/heparin IgGAM by a commercial EIA, and rapid increase of platelet count after switching from heparin to lepirudin. Criteria to diagnose HIT in patient 3 were platelet decrease greater than 50% after 7 days of heparin treatment, positive anti-PF4/heparin IgGAM by a commercial EIA, and rapid increase of platelet count after switching from heparin to lepirudin. CPB indicates cardiopulmonary bypass; IABP, intraaortic balloon pump; and OD, optical density.