New ASH guidelines on management of heparin-induced thrombocytopenia

The American Society of Hematology (ASH) has released a new guideline on the diagnosis and management of heparin-induced thrombocytopenia (HIT), published online Nov. 27, 2018 in the journal Blood Advances.

The guideline covers various aspects of the condition including screening of asymptomatic patients for HIT, diagnosis and initial management of patients with suspected HIT, treatment of acute HIT. It incorporates the use of direct oral anticoagulants as additional options for non-heparin anticoagulants.

Some key recommendations include:

·         The use of the 4Ts score is recommended in patients with suspected HIT rather than a gestalt approach to estimate the probability of HIT. If there is an intermediate- or high-probability 4Ts score, an immunoassay should be done. The guideline however cautions that every effort should be made to obtain accurate and complete information necessary to calculate the 4Ts score. If key information is missing, it may be prudent to err on the side of a higher 4Ts score.

·         In patients with suspected HIT and a low probability 4Ts score, the guideline recommends against empiric treatment of HIT (i.e., against discontinuation of heparin and initiation of a non-heparin anticoagulant)

·         Heparin should be discontinued and a non-heparin anticoagulant at therapeutic intensity should be initiated in patients with suspected HIT and a high-probability 4Ts score.

·         In patients with acute HIT complicated by thrombosis (HITT) or acute HIT without thrombosis (isolated HIT), discontinuation of heparin and initiation of a non-heparin anticoagulant is recommended.

·         Patients with acute HITT or acute isolated HIT should be treated with a non-heparin anticoagulant at therapeutic-intensity dosing rather than prophylactic-intensity dosing.

·         In patients with acute HIT or subacute HIT A (with normal platelet count) who require cardiovascular surgery, the procedure should be delayed until the patient has subacute HIT B or remote HIT.

·         In patients with acute HIT who are receiving renal replacement therapy and require anticoagulation to prevent thrombosis of the dialysis circuitry, treatment with argatroban, danaparoid, or bivalirudin rather than other non-heparin anticoagulants is recommended.

·  In patients with remote HIT who require treatment or prophylaxis for venous thromboembolism (VTE), a non-heparin anticoagulant (e.g., apixaban, dabigatran, danaparoid, edoxaban, fondaparinux, rivaroxaban, or vitamin K antagonists [VKA]) should be administered rather than unfractionated heparin (UFH) or low molecular weight heparin (LMWH).

·         Treatment with bivalirudin rather than a different non-heparin anticoagulant is recommended in patients with acute HIT or subacute HIT A who require percutaneous coronary intervention (PCI).

·         In patients with acute isolated HIT, bilateral lower-extremity compression ultrasonography is suggested to screen for asymptomatic proximal deep venous thrombosis (DVT).

·         Anticoagulation be continued, at a minimum, until platelet count recovery (usually a platelet count of ≥150 3 10⁹ /L) in patients with acute isolated HIT and no asymptomatic DVT identified by screening compression ultrasonography.

(Source: Blood Adv. 2018;2(22):3360)

Dr KK Aggarwal

Padma Shri Awardee

President Elect Confederation of Medical Associations in Asia and Oceania   (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA