Fig. 1.

Platelet counts in relation to heparin treatment in 3 patients with VITT. For patients 1 and 2, heparin treatment was given prior to clinical recognition of VITT; for patient 3 heparin treatment was given for an 8-day period during which high-dose IVIG and TPE were administered, and after demonstration in vitro that the patient's serum did not enhance platelet activation in the presence of heparin. None of the patients showed an abrupt drop in platelet count upon starting heparin; rather, platelet counts increased in all 3 patients (although the platelet counts returned to pre-heparin baseline in patient 2). For patients 1 and 2, available fibrinogen data indicated that heparin administration was associated with a decrease in consumptive coagulopathy, as shown by rising fibrinogen levels. Data obtained from 3 patients reported elsewhere [24]. Data for patients 1 and 2 reprinted with permission of the Massachusetts Medical Society (data for patient 3 in Fig. 1 has not been reported previously). aPTT, activated partial thromboplastin time; IV, intravenous; IVIG, intravenous immune globulin; SC, subcutaneous; TPE, therapeutic plasma exchange; U, units; UFH, unfractionated heparin.