Outcomes Of Platelet Transfusion In Heparin Induced Thrombocytopenia Patients

Heparin induced thrombocytopenia (HIT) is an immune mediated adverse reaction to heparin characterized by thrombosis and thrombocytopenia. Current guidelines recommend against the transfusion of platelets in patients with HIT based on a small number of reports suggesting adverse neurologic outcomes or mortality within hours of platelet transfusion. A more recent study, however, described no adverse outcomes in patients with HIT who received platelet transfusion.

Currently, there is a paucity of literature and ambiguity in regards to the safety of platelet transfusion for patients with HIT. To analyze our experience in these situations, we examined the outcomes of patients who received platelet transfusions during the admission for HIT to our institution, which is a large tertiary care referral center.

We reviewed records of patients admitted with a diagnosis of HIT from 9/2002 to 9/2012. The inclusion criteria included (1a) positive serotonin release assay (SRA), defined as >20% release, or (1b) intermediate/high “4T risk score” and HPF-4 optical density (OD) > 0.4, if SRA was not available and (2) platelet transfusion within 30 days of HIT diagnosis. Any adverse outcome, such as death, myocardial infarction, stroke, DVT/PE, worsened thrombocytopenia, or bleeding that occurred within 24 hours of the transfusion was recorded, along with indication for transfusion and increment in platelet count post-transfusion. A minimum increase in platelet count of 10,000/μL was considered adequate. Patients’ demographic characteristics, active malignancy, history of thromboembolic event, CVA or CAD within past 30 days of admission were also recorded.

In our analysis of 1720 patients, 24 met the inclusion criteria, who received a total of 42 transfusions. We did not find any adverse outcomes within 24 hours of platelet transfusion. A 66-year-old female developed right parietal infarct 36 hours after transfusion, which was deemed unrelated. Of note, she had a past medical history of hypertension, diabetes mellitus II, hyperlipidemia and deep venous thrombosis. Three patients (12.5%) died during the admission, two of which were due to sepsis and one due to advanced malignancy. The most common reason for transfusion was empiric either (a) prior to an invasive procedure/surgery in 52.4% (22/42) (median platelet count 52,000/μL, range 15,000-151,000/μL), or (b) due to “low count” in 28.6% (12/42) (median count 18,000/μL, range 7,000-31,000/μL), followed by (c) therapeutic due to bleeding in 14.3% (6/42) (median platelet count 52,500/μL, range 27,000-219,000/μL). The median time to platelet transfusion was 7 days (range <1 to 22 days) from the time of diagnosis. Median increment in platelet count was 27,500/μL (range 4,000-112,000/μL); one transfusion did not result in adequate increment while 10 had missing information. Adequate hemostasis was achieved in 50% (3/6) transfusions given due to bleeding. A total of 52 packs of pooled platelets were transfused.

None of the patients had any adverse event related to platelet transfusion. One patient had a thrombotic event 36 hours post transfusion. Our data does not suggest against platelet transfusions in patients with HIT, if clinically indicated.

No relevant conflicts of interest to declare.