Platelet response to direct thrombin inhibitor or fondaparinux treatment in patients with suspected heparin-induced thrombocytopenia

Abstract

Making a definitive diagnosis of heparin-induced thrombocytopenia (HIT) can be problematic. A prompt platelet rise following treatment has been proposed as a "post-test" criterion for diagnosis. However, the platelet response following discontinuation of heparin and initiation of a recommended alternative anticoagulant remains largely undefined and unstudied. This study aimed to characterize platelet response to initial treatment in patients with a low, intermediate, or high likelihood of having HIT. This was a multicenter retrospective cohort study. Patients were over 18 years in age, underwent serologic testing for HIT, and received alternative anticoagulation treatment for HIT. Classification of each patient's likelihood of having HIT was based on an empiric, pre-hoc combination of the 4T score and serology results. The primary outcome for this study was a platelet count response after initiation of direct thrombin inhibitor (DTI) or fondaparinux therapy within 48 h. 124 patients were analyzed. The sensitivity and specificity of having an immediate platelet rise of at least 10,000/µL by day 2 after starting treatment among high-likelihood for HIT patients were 0.71 (95% CI 0.55-0.84) and 0.64 (95% CI 0.5-0.76), respectively. The negative predictive value of no platelet rise was 75.5% (95% CI 0.61-0.86). A prompt platelet count rise may be appropriate to consider along with other known criteria for the clinical diagnosis of HIT. The rise should be immediate following discontinuation of heparin and initiation of recommended treatment, with an upward rise within 48 h.

Cerebral venous sinus thrombosis after COVID-19 vaccination: a case report and literature review

“…Anticoagulation with heparin or warfarin should be avoided [ 16 ]. Platelet count should be monitored for recovery, and recovery itself is identified as platelet count of > 150 × 10 9 /mm 3 [ 17 ]. Even in some cases of intracranial hemorrhage, anticoagulation should be considered to prevent progressive thrombosis.…”

American Society of Hematology 2018 guidelines for management of venous thromboembolism: heparin-induced thrombocytopenia

“…Platelet count recovery occurs within 7 days in 90% of cases, although it may take weeks in a minority of patients. 39,40 Functional assays become negative at a median of 50 days after heparin is suspended. Circulating anti-PF4/heparin antibodies are no longer detectable by immunoassay at a median of 85 days.…”

Recommendations on the use of anticoagulants for the treatment of patients with heparin-induced thrombocytopenia in Switzerland

“…This therapeutic approach might constitute an important adjunct treatment to anticoagulation in patients with HIT [8,9]. Efficient treatment of HIT will lead to the normalisation of the platelet count (typically within 5-7 days) and prompt mitigation of the hypercoagulable state [10,11].…”