Unexpected Heparin-Induced Thrombocytopenia While Bridging

To the Editor Kulkarni and Fang, in their engaging and instructive Teachable Moment, discuss the indications, merits, demerits, and dangers of bridging anticoagulation. However, they do not address the possibility that, in the present patient, the bleeding complication may have been, at least in part, due to heparin-induced thrombocytopenia (HIT) resulting in a bleeding diathesis. Heparin-induced thrombocytopenia occurs in 2 forms. Type 2 is the most injurious. This is an autoimmune-mediated activation of platelets triggered by heparin. It results in a generally prothrombotic state. Type 1 results from a direct activation of platelets by heparin resulting in a decline in platelet numbers. It can occur in up to 30% of patients medicated with heparin. Combined with an elevation in the international normalized ratio, HIT type 1 may result in the bleeding proclivity observed by the authors. Given that the authors do not explicitly mention the platelet count, it is unlikely that the bleeding events in this case were attributable to HIT. Nonetheless, HIT remains an important complication to bear in mind in patients receiving heparin therapy.
Source: JAMA Internal Medicine - Category: Internal Medicine Source Type: research