Even untainted heparin can carry adverse side effects

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Amid the recent reports of death related to tainted heparin, several studies at the ACC conference revealed thrombocytopenia often accompanies untainted heparin usage.

Thrombocytopenia is any disorder in which there are not enough platelets, and is sometimes associated with abnormal bleeding, according to the National Institutes of Health (NIH).

The CATCH (Complications After Thrombocytopenia Caused by Heparin Registry) study was designed to evaluate the risk of thrombocytopenia among patients receiving heparin in diverse clinical settings.

Among 1,017 patients receiving heparin venous thromboembolism (VTE) prophylaxis, 190 (19 percent) developed thrombocytopenia, according to Tracy Y. Wang and colleagues from Duke University Medical Center, Durham, N.C.

The CATCH researchers found that for thrombocytopenic patients, heparin-induced thrombocytopenia serologies were obtained in 5 percent, and a hematology consult was obtained in 3 percent, but none were switched to a direct thrombin inhibitor. They reported that heparin was continued in 170 patients (89.5 percent) for a median of 162 hours after the nadir platelet count.

The CATCH investigators reported that acquired thrombocytopenia was associated with increased mortality (3.7 vs. 0.7 percent) and both thrombotic and bleeding complications (11.1 vs. 7.1; 16.5 vs. 4.9).

Thrombocytopenia occurs frequently in patients on heparin VTE prophylaxis and is associated with worse outcomes, and careful platelet count monitoring and prompt heparin discontinuation in these patients may improve outcomes, concluded Wang and her CATCH colleagues. 

In another study conducted by Wang and colleagues from both Duke and the University of Cincinnati College of Medicine, researchers stratified 42,580 acute coronary syndrome (ACS) patients with normal admission platelet counts in the CRUSADE initiative (2004-2006) into three groups based on nadir platelet counts: normal >150, mild 100-150, and moderate/severe thrombocytopenia <100 x109/L.

The CRUSADE researchers reported that a total of 6,168 (15 percent) patients developed mild thrombocytopenia and 1,542 (4 percent) had moderate or severe thrombocytopenia. These patients were older and more likely to have lower body mass, diabetes and renal insufficiency than patients without thrombocytopenia.

Unfractionated heparin therapy was more commonly used in the thrombocytopenic groups (normal 56 percent vs. mild 60 percent vs. moderate or severe 62 percent), according to the CRUSADE investigators. Higher risks of bleeding, transfusion and mortality were observed with increasing severity of thrombocytopenia.

Wang and her CRUSADE colleagues concluded that approximately one in five patients treated with contemporary ACS therapies developed new thrombocytopenia that was associated with increased bleeding and mortality.

Researchers recommended that their findings warrant further evaluation because “even mild thrombocytopenia is of clinical significance.”