Guideline sources The following summarized guidelines for the evaluation and management of heparin-induced thrombocytopenia (HIT) are prepared by our editorial team based on guidelines from the Society for Cardiovascular Angiography and Interventions (SCAI/AHA/ACC 2022), the French Working Group on Perioperative Hemostasis (GIHP 2020), the European Society of Cardiology (ESC/EACTS 2019), the Canadian Association of Interventional Cardiology (CAIC 2019), the American Society of Hematology (ASH 2018), the Society for Vascular Surgery (SVS 2018), the European Society of Cardiology (ESC 2018), the Canadian Consensus Group on Venous Thromboembolism in Cancer (CCG-VTEC 2015), the Society of Obstetricians and Gynaecologists of Canada (SOGC 2014), the American College of Chest Physicians (ACCP 2012), the British Committee for Standards In Haematology (BCSH 2012), and the Kidney Disease: Improving Global Outcomes Foundation (KDIGO 2012). 1 2 3 4 5 6 7 8 9 10 11 12 https://web.pathway.md/diseases/recR76V6DESBdk0f1 1/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway Calculator4Ts score for heparin-induced t Guidelines 1. Screening and diagnosis Indications for monitoring, baseline platelet count: As per GIHP 2020 guidelines, obtain baseline measurement of platelet count before initiating heparin (or alternatively as soon as possible after the first injection, before day 4), whether UFH or LMWH. E As per ACCP 2012 guidelines, obtain baseline measurement of platelet count before initiating heparin or LMWH in patients exposed to heparin within the past 100 days. Repeat platelet count measurement 24 hours later, if feasible. E As per BCSH 2012 guidelines, obtain baseline measurement of platelet count in patients receiving any heparin. B Indications for monitoring, low risk: As per GIHP 2020 guidelines, consider obtaining platelet count monitoring in patients at low risk of HIT. E As per ASH 2018 guidelines, avoid obtaining platelet count monitoring to screen for HIT in patients at low risk (< 0.1%). D As per ACCP 2012 guidelines, avoid obtaining platelet count monitoring in patients at low risk (< 1%) of HIT. D As per BCSH 2012 guidelines, do not obtain routine platelet monitoring in medical patients and obstetric patients receiving heparin. D Indications for monitoring, moderate-to-high risk: As per GIHP 2020 guidelines: Consider obtaining platelet count monitoring 1-2 times a week from day 4 to day 14 of treatment, and then once weekly for 1 month if heparin therapy is continued, in patients at intermediate risk of HIT. E Consider obtaining platelet count monitoring 2-3 times a week from day 4 to day 14 of treatment, and then once weekly for 1 month if heparin therapy is continued, in patients at high risk of HIT. E As per ASH 2018 guidelines, consider obtaining platelet count monitoring in patients at intermediate (0.1-1.0%) or high risk (> 1.0%) of HIT. C Show 2 more https://web.pathway.md/diseases/recR76V6DESBdk0f1 2/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway As per ACCP 2012 guidelines, consider obtaining platelet count monitoring every 2-3 days from day 4 to day 14 if the risk of HIT is > 1%. C Indications for monitoring (after surgery): obtain platelet count monitoring every 2-3 days from day 4 to day 14 or until heparin is stopped in postoperative patients, including obstetric cases, receiving UFH. B Show 3 more Indications for monitoring, recent heparin exposure: As per ASH 2018 guidelines, consider obtaining platelet count monitoring starting from day 0 (the day heparin is initiated) if the patient has received heparin in the previous 30 days. C As per ACCP 2012 guidelines, obtain baseline measurement of platelet count before initiating heparin or LMWH in patients exposed to heparin within the past 100 days. Repeat platelet count measurement 24 hours later, if feasible. E As per BCSH 2012 guidelines, obtain platelet count measurement 24 hours after initiating heparin in postoperative patients (including cardiopulmonary bypass) receiving any type of heparin and having a history of heparin exposure within the past 100 days. B Indications for testing, low pretest probability: As per GIHP 2020 guidelines, do not obtain specific laboratory evaluation for the exclusion of HIT in patients with low (4T 3) pretest probability. Obtain close monitoring of platelet count to search for an etiology of thrombocytopenia. D As per ASH 2018 guidelines, do not obtain laboratory testing in patients with low pretest probability based on the 4Ts score. D As per BCSH 2012 guidelines, do not obtain laboratory evaluation for the exclusion of HIT in patients with low pretest probability. D Indications for testing, moderate-to-high pretest probability: As per GIHP 2020 guidelines, obtain biological tests to detect anti-PF4 antibodies in patients with intermediate (4T = 4-5) or high (4T 6) pretest probability. E Show 2 more As per ASH 2018 guidelines, obtain an immunoassay in patients with an intermediate or high pretest probability based on the 4Ts score. B Consider obtaining a functional assay, if available, either locally or as a send-out test to a reference laboratory, in patients with positive immunoassay results. B As per BCSH 2012 guidelines, obtain laboratory testing in patients with an intermediate or high pretest probability of HIT. B Indications for testing, acute systemic reaction: As per GIHP 2020 guidelines, consider obtaining platelet count monitoring in all patients receiving heparin and experiencing an unexpected clinical event (onset or aggravation of venous or arterial thrombosis, skin necrosis, or unusual reaction after heparin injection, such as chills, low BP, dyspnea, amnesia), regardless of the risk of HIT. E https://web.pathway.md/diseases/recR76V6DESBdk0f1 3/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway As per ACCP 2012 guidelines, consider obtaining platelet count measurement in patients presenting with acute systemic reactions within 30 minutes of an IV heparin bolus. E As per BCSH 2012 guidelines, suspect and assess for HIT in patients with new thrombosis, skin allergy, or any other rarer manifestations of HIT developing between day 4 and day 14 of heparin administration. B Diagnosis: As per GIHP 2020 guidelines, consider excluding HIT based on a low (4T 3) pretest probability without specific bioassays. Obtain close monitoring of platelet count to search for an etiology of thrombocytopenia. E Show 3 more As per BCSH 2012 guidelines, suspect HIT if the platelet count falls by 30% between days 4 and 14 of heparin administration. B Show 4 more 2. Classification and risk stratification Pretest probability: As per GIHP 2020 guidelines: Use the 4T score (outside a cardiac surgery context) to determine the clinical probability of HIT in patients with suspected HIT. E Consider classifying the risk of HIT during heparin administration into three groups: Situation Guidance Treatment with LMWH in medicine (except cancer), obstetrics (except surgery including C-section), or in the course of minor trauma Low (< 0.1%) Treatment with fondaparinux Isolated UFH injection for an endovascular procedure or simple surgery Treatment with UFH or LMWH lasting > 1 month Prophylactic treatment with UFH in medicine/obstetrics Intermediate (0.1-1%) Prophylactic treatment with LMWH in patients with cancer or severe trauma or in postoperative care (including cardiac surgery) Prophylactic treatment with UFH in surgery (including circulatory assistance) or for High (> 1%) https://web.pathway.md/diseases/recR76V6DESBdk0f1 4/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway RRT All curative treatments with UFH in medicine/surgery/obstetrics. E As per ASH 2018 guidelines, use the 4Ts score rather than a gestalt approach to estimate the probability of HIT in patients with suspected HIT. B Classification: Consider classifying HIT into three stages: Situation Guidance Diagnosed within the last month Acute HIT Anti-PF4 antibodies most often present with a high thrombotic risk Diagnosed 1-3 months ago Subacute HIT Anti-PF4 antibodies often present with a low titer Diagnosed > 3 months ago Previous history of HIT Anti-PF4 antibodies most often are undetectable. E 3. Diagnostic investigations Immunoassays: As per GIHP 2020 guidelines: Consider obtaining anti-PF4 antibodies as soon as possible in patients with suspected HIT with intermediate or high clinical probability. E Obtain biological tests to detect anti-PF4 antibodies in patients with intermediate (4T = 4-5) or high (4T 6) pretest probability. E As per ASH 2018 guidelines, obtain an immunoassay in patients with suspected HIT with an intermediate or high pretest probability based on the 4Ts score. B As per BCSH 2012 guidelines: Obtain an antigen assay of high sensitivity in non-expert laboratories. Measure only the IgG class. Report actual optical density, degree of inhibition by high dose heparin, and the cut-off point for a positive test rather than simply the test as positive or negative. B Do not obtain platelet aggregation assays using platelet-rich plasma because of lack of sensitivity. D Platelet function tests: As per GIHP 2020 guidelines, obtain a platelet function test to confirm the diagnosis of HIT in patients with intermediate or high clinical probability and a significant titer of anti-PF4 antibodies. https://web.pathway.md/diseases/recR76V6DESBdk0f1 5/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway E As per ASH 2018 guidelines, consider obtaining a functional assay, if available, either locally or as a send-out test to a reference laboratory, in patients with suspected HIT with positive immunoassay results. C As per BCSH 2012 guidelines, recognize that platelet activation assays using washed platelets (heparin-induced platelet activation assay and serotonin release assay) have a higher sensitivity than platelet aggregation assays using platelet-rich plasma and are regarded as the reference standard, but are technically demanding. Restrict their use to experienced laboratories. B Screening for asymptomatic DVT: Consider obtaining bilateral lower-extremity compression ultrasound to screen for asymptomatic proximal deep vein thrombosis in patients with acute isolated HIT. C Consider obtaining upper-extremity ultrasound in the limb with the catheter to screen for asymptomatic deep vein thrombosis in patients with acute isolated HIT and an upper-extremity central venous catheter. Avoid obtaining upper-extremity ultrasound in limbs without central venous catheters. C 4. Medical management Continuation of heparin: As per GIHP 2020 guidelines, consider continuing or resuming heparin therapy, with close monitoring of platelet count, after the exclusion of HIT based on the absence of anti-PF4 antibodies in patients with intermediate clinical probability. E As per ASH 2018 guidelines, do not discontinue heparin empirically in patients with suspected HIT with a low probability score. D Discontinuation of heparin: As per GIHP 2020 guidelines, discontinue heparin immediately (without waiting for the results of biological tests) and initiate a non-heparin anticoagulant at curative doses in patients with a high (4T 6, or extracorporeal circulation with biphasic platelet count progression profile) clinical probability of HIT. E As per ASH 2018 guidelines, discontinue heparin in patients with an intermediate probability of HIT with no other indications for therapeutic-intensity anticoagulation. B Consider initiating a non-heparin anticoagulant at prophylactic or therapeutic doses in patients with or without a high risk of bleeding, respectively. B Show 4 more As per BCSH 2012 guidelines: Discontinue heparin and initiate full-dose anticoagulation with an alternative anticoagulant in patients with suspected (non-low pretest probability) or confirmed HIT. B Take the risks and benefits of treatment with an alternative anticoagulant into consideration when making clinical decisions. B Initiation of non-heparin anticoagulants, HIT without thrombosis, general principles: https://web.pathway.md/diseases/recR76V6DESBdk0f1 6/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway As per GIHP 2020 guidelines: Initiate a non-heparin anticoagulant (such as argatroban, bivalirudin, danaparoid, fondaparinux, or a DOAC) as an alternative anticoagulant in the acute phase of HIT. E Consider initiating any available non-heparin anticoagulant in stable patients with acute HIT with no severe renal or hepatic impairment and no risk of bleeding (absence of comorbidity or recent or expected invasive procedure in the short-term). E As per ASH 2018 guidelines: Initiate a non-heparin anticoagulant at therapeutic intensity, rather than prophylactic intensity dosing, in patients with acute isolated HIT. (strong recommendation, moderate certainty in the evidence about effects. B Consider initiating argatroban, bivalirudin, danaparoid, fondaparinux, or a DOAC when a non- heparin anticoagulant is being selected. C As per CCG-VTEC 2015 guidelines, initiate a non-heparin agent (including lepirudin, argatroban, and danaparoid; off-label agents include bivalirudin and fondaparinux) in patients with strongly suspected or confirmed HIT without thrombosis. A Initiation of non-heparin anticoagulants, HIT without thrombosis, direct thrombin and factor Xa inhibitors: As per GIHP 2020 guidelines, administer IV danaparoid at curative doses (not at prophylactic doses) and monitor anti-Xa activity with a specific calibration curve in patients with HIT. Replace danaparoid with another anticoagulant if the platelet count is not corrected or if a thrombosis under danaparoid appears or spreads. E Show 5 more As per ACCP 2012 guidelines: Initiate lepirudin, argatroban, or danaparoid over the continuation of heparin/LMWH or initiation/continuation of vitamin K antagonists in patients with isolated HIT (HIT without thrombosis). B Consider initiating argatroban, lepirudin, or danaparoid over other non-heparin anticoagulants in patients with isolated HIT (HIT without thrombosis) with normal renal function. C As per BCSH 2012 guidelines, initiate danaparoid at therapeutic doses, but not prophylactic doses, as a suitable alternative anticoagulant in patients with HIT. B Consider obtaining an anti-Xa assay with specific danaparoid calibrators to monitor the anticoagulant effect of danaparoid in patients > 90 kg or with a GFR < 30 mL/min. B Show 2 more Initiation of non-heparin anticoagulants, HIT without thrombosis, direct oral anticoagulants: As per GIHP 2020 guidelines, consider initiating a DOAC (without specific biological monitoring) as a first-line alternative anticoagulant (due to the simplicity of its use), after the use of danaparoid or argatroban, in stable patients with acute HIT. E As per ASH 2018 guidelines: Consider initiating a DOAC when a non-heparin anticoagulant is being selected in patients with acute isolated HIT. C https://web.pathway.md/diseases/recR76V6DESBdk0f1 7/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway Consider initiating a DOAC (dabigatran, rivaroxaban, or apixaban) rather than a vitamin K antagonist in patients with subacute HIT A. C Initiation of non-heparin anticoagulants, HIT without thrombosis, vitamin K antagonists: As per GIHP 2020 guidelines, initiate vitamin K antagonists as a supplement to parenteral treatment in the acute phase of HIT only when the platelet count is corrected (> 150, 000/ L). E As per ASH 2018 guidelines, do not initiate vitamin K antagonists before platelet count recovery (usually 150, 000/ L) in patients with acute isolated HIT. D As per CCG-VTEC 2015 guidelines, do not initiate warfarin in patients with strongly suspected or confirmed HIT until after the platelet count has substantially recovered ( 150, 000/ L). D As per BCSH 2012 guidelines: Do not initiate warfarin until the platelet count has recovered to the normal range. Continue the alternative anticoagulant until the INR is therapeutic when introducing warfarin. Recognize that argatroban affects the INR and take this into consideration when using this drug. Ensure a minimum overlap of 5 days between non-heparin anticoagulants and vitamin K antagonist therapy. D Administer IV vitamin K for reversal if the patient has received a vitamin K antagonist at the time of diagnosis. B Initiation of non-heparin anticoagulants, HIT with thrombosis, general principles: As per ASH 2018 guidelines: Initiate a non-heparin anticoagulant at therapeutic intensity, rather than prophylactic intensity dosing, (strong recommendation, very low certainty in the evidence about effects) in patients with acute HIT complicated by thrombosis. B Consider initiating argatroban, bivalirudin, danaparoid, fondaparinux, or a DOAC when a non- heparin anticoagulant is being selected. C As per CCG-VTEC 2015 guidelines, initiate a non-heparin agent (including lepirudin, argatroban, and danaparoid; off-label agents include bivalirudin and fondaparinux) in patients with strongly suspected or confirmed HIT complicated by thrombosis. A Initiation of non-heparin anticoagulants, HIT with thrombosis, direct thrombin and factor Xa inhibitors: As per GIHP 2020 guidelines: Replace danaparoid with another anticoagulant when a thrombosis under danaparoid appears or spreads. E Consider administering injectable argatroban or bivalirudin, combined with strict biological monitoring, in patients with acute severe HIT (massive pulmonary embolism, extensive or arterial thrombosis, venous gangrene, coagulopathy of consumption). E As per ACCP 2012 guidelines, initiate non-heparin anticoagulants, in particular lepirudin, argatroban, or danaparoid, over the continuation of heparin or LMWH or initiation/continuation of vitamin K antagonists in patients with HIT complicated by thrombosis. B Consider initiating https://web.pathway.md/diseases/recR76V6DESBdk0f1 8/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway lepirudin, argatroban, or danaparoid over other non-heparin anticoagulants in patients with normal renal function. B Initiation of non-heparin anticoagulants, HIT with thrombosis, vitamin K antagonists: As per ASH 2018 guidelines, do not initiate vitamin K antagonists before platelet count recovery (usually 150, 000/ L) in patients with acute HIT complicated by thrombosis. D As per ACCP 2012 guidelines, do not initiate vitamin K antagonist until platelets have substantially recovered (usually to at least 150, 000/ L). Start vitamin K antagonists initially at low doses (maximum 5 mg of warfarin or 6 mg phenprocoumon) in patients with strongly suspected or confirmed HIT. D Show 2 more Duration of anticoagulation: As per ASH 2018 guidelines, consider continuing anticoagulation at least until platelet count recovery (usually 150, 000/ L) in patients with acute isolated HIT and no asymptomatic deep vein thrombosis identified by screening compression ultrasound. Avoid continuing treatment for 3 months unless HIT persists without platelet count recovery. C As per ACCP 2012 guidelines, consider continuing alternative anticoagulant therapy (including vitamin K antagonists) for 4 months in patients with isolated HIT and for 3 weeks in patients with HIT complicated by thrombosis. E As per BCSH 2012 guidelines, continue therapeutic anticoagulation for 4 months after HIT without a thrombotic complication B and for 3 weeks following HIT with a thrombotic complication. A Antiplatelet therapy: As per GIHP 2020 guidelines, do not use oral antiplatelet agents for the treatment of patients with acute HIT. D As per ASH 2018 guidelines, avoid using antiplatelet agents in combination with non-heparin anticoagulants in patients with acute HIT (whether acute isolated HIT or complicated by thrombosis) and no other indication for antiplatelet therapy. D Intravenous immunoglobulin: do not use IVIGs as first-line therapy in the acute phase of HIT. D 5. Therapeutic procedures Platelet transfusion: As per GIHP 2020 guidelines, do not administer platelet transfusion in the acute phase of HIT in the absence of life-threatening or functional bleeding. D As per ASH 2018 guidelines, avoid administering platelet transfusions routinely in patients with acute HIT, whether acute isolated HIT or complicated by thrombosis, at average bleeding risk. D https://web.pathway.md/diseases/recR76V6DESBdk0f1 9/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway As per ACCP 2012 guidelines, consider administering platelet transfusions in patients with severe thrombocytopenia only in case of bleeding or when performing an invasive procedure with a high risk of bleeding. C As per BCSH 2012 guidelines, consider administering platelet transfusions in the event of bleeding C but not for prophylaxis. B Inferior vena cava filter placement: As per GIHP 2020 guidelines, do not insert an IVC filter in the acute phase of HIT. D As per ASH 2018 guidelines, do not insert an IVC filter routinely in patients with acute HIT, whether acute isolated HIT or complicated by thrombosis. D 6. Specific circumstances Pediatric patients: Consider using the same procedures for monitoring platelet counts in pediatric patients treated with heparin as in adult patients. E Initiate sodium danaparoid or argatroban, with rigorous dose adjustment based on weight and bioassay results, in pediatric patients with HIT. E Pregnant patients, management: As per GIHP 2020 guidelines, consider preferring danaparoid, or fondaparinux if danaparoid is not available, in pregnant patients with HIT. E As per ACCP 2012 guidelines, consider initiating danaparoid over other non-heparin anticoagulants in pregnant patients with acute or subacute HIT. Consider initiating lepirudin or fondaparinux only when danaparoid is not available. C As per BCSH 2012 guidelines, initiate a non-cross-reacting anticoagulant (danaparoid, where available, or fondaparinux) in pregnant patients with HIT. B Pregnant patients (diagnosis): Recognize that HIT in pregnant women is extremely rare. B Obtain baseline measurement platelet count, and repeat testing a week later, to screen for HIT in pregnant patients initiated on therapeutic LMWH. B Patients with hepatic impairment: Initiate argatroban at 1 g/kg/min and reduce it to 0.5 g/kg/min in patients with moderate hepatic failure (Child-Pugh B). E Consider initiating bivalirudin, danaparoid, or fondaparinux in patients with acute HIT with severe hepatic impairment (Child-Pugh C). Do not use argatroban in patients with severe hepatic impairment. E Patients with renal impairment: As per GIHP 2020 guidelines: Initiate argatroban for HIT in patients with severe renal failure (CrCl < 30 mL/min). E https://web.pathway.md/diseases/recR76V6DESBdk0f1 10/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway Do not use danaparoid as first-line therapy in patients with severe renal failure. D As per ACCP 2012 guidelines, consider initiating argatroban over other non-heparin anticoagulants in patients with renal impairment. C As per BCSH 2012 guidelines, consider obtaining an anti-Xa assay with specific danaparoid calibrators to monitor the anticoagulant effect of danaparoid in patients with a GFR < 30 mL/min. C Patients requiring renal replacement therapy: As per GIHP 2020 guidelines: Consider using citrate or argatroban as the preferred treatment for circuit anticoagulation for RRT in the case of HIT. E Consider administering citrate or argatroban as the preferred treatment for circuit anticoagulation in patients with HIT undergoing RRT. E As per ASH 2018 guidelines: Consider administering argatroban, danaparoid, or bivalirudin rather than other non-heparin anticoagulants in patients with acute HIT receiving RRT and requiring anticoagulation to prevent thrombosis of the dialysis circuitry. C Consider administering regional citrate rather than heparin or other non-heparin anticoagulants in patients with subacute HIT A, subacute HIT B, or remote HIT receiving RRT, not otherwise receiving anticoagulation, and requiring anticoagulation to prevent thrombosis of the dialysis circuit. C As per ACCP 2012 guidelines: Consider administering argatroban or danaparoid over other non-heparin anticoagulants in patients with acute or subacute HIT requiring RRT. C Consider administering regional citrate over heparin or LMWH in patients with a previous history of HIT requiring ongoing RRT or catheter locking. C As per KDIGO 2012 guidelines: Administer direct thrombin inhibitors (such as argatroban) or factor Xa inhibitors (such as danaparoid or fondaparinux) during RRT in patients with HIT. B Consider administering argatroban rather than other thrombin or factor Xa inhibitors during RRT in patients with HIT without severe liver failure. C Patients requiring PCI: As per ACC 2022 guidelines, initiate bivalirudin or argatroban to replace UFH to avoid thrombotic complications in patients with HIT undergoing PCI. B As per GIHP 2020 guidelines, consider initiating bivalirudin or an analog, or argatroban if it fails, in patients with acute HIT requiring transluminal angioplasty for ACS . E As per CAIC 2019 guidelines, initiate bivalirudin over UFH or LMWH for procedural anticoagulation in patients with STEMI and a history of HIT undergoing primary PCI. B As per ESC 2019 guidelines, initiate bivalirudin (0.75 mg/kg bolus, followed by 1.75 mg/kg/hour for up to 4 hours after the procedure) in patients with HIT undergoing PCI. B https://web.pathway.md/diseases/recR76V6DESBdk0f1 11/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway As per ASH 2018 guidelines: Consider initiating bivalirudin rather than other non-heparin anticoagulants in patients with acute HIT or subacute HIT A requiring PCI. C Consider initiating bivalirudin rather than UFH in patients with subacute HIT B or remote HIT requiring PCI. C As per ESC 2018 guidelines, initiate bivalirudin as the anticoagulant agent of choice in patients with HIT undergoing primary PCI. B As per ACCP 2012 guidelines: Consider initiating bivalirudin C or argatroban over other non-heparin anticoagulants in patients with acute or subacute HIT requiring PCI. C Offer the same treatment in patients with a history of HIT requiring cardiac catheterization or PCIs as in patients with acute or subacute HIT. As per BCSH 2012 guidelines, initiate bivalirudin in patients with previous or present HIT requiring coronary intervention, including angiography and PCI. B Patients requiring cardiac surgery: As per GIHP 2020 guidelines, consider obtaining an ELISA for anti-PF4 antibodies before any cardiac surgery in patients with a documented history of HIT. E Show 2 more As per ASH 2018 guidelines, delay surgery until the patient has subacute HIT B or remote HIT, if feasible, in patients with acute HIT or subacute HIT A requiring cardiovascular surgery. Show 2 more As per SVS 2018 guidelines, administer a thrombin inhibitor, such as bivalirudin or argatroban, as an alternative to heparin in patients with a history of HIT undergoing open surgical repair of an AAA. B As per ACCP 2012 guidelines, consider administering bivalirudin over other non-heparin anticoagulants and over heparin plus antiplatelet agents in patients with acute (thrombocytopenic, antibody-positive HIT) or subacute (platelets recovered, but still antibody- positive HIT) HIT requiring urgent cardiac surgery. C Show 2 more As per BCSH 2012 guidelines, administer intraoperative UFH in preference to other anticoagulants in antibody-negative (usually after > 100 days) patients with previous HIT requiring cardiac surgery. Initiate an anticoagulant other than UFH or LMWH for pre- and postoperative anticoagulation. B Patients requiring non-cardiac surgery: consider postponing any surgery beyond the first month following the diagnosis of acute HIT (< 1 month) if this does not generate a major vital or functional risk for the patient. Define the modalities during a multidisciplinary consultation. E Show 2 more Patients with non-HIT related thrombosis: consider initiating fondaparinux at full therapeutic doses until the transition to vitamin K antagonists in patients with a past history of HIT presenting https://web.pathway.md/diseases/recR76V6DESBdk0f1 12/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway with an acute thrombosis (not related to HIT) and normal renal function. C 7. Preventative measures Secondary prevention: As per GIHP 2020 guidelines, consider initiating an OAC (vitamin K antagonist or DOAC) or fondaparinux in patients with a history of HIT requiring prophylactic or curative anticoagulation. Consider initiating argatroban, bivalirudin, or danaparoid only when OACs and fondaparinux are contraindicated. E As per ASH 2018 guidelines, initiate a non-heparin anticoagulant (such as apixaban, dabigatran, danaparoid, edoxaban, fondaparinux, rivaroxaban, or a vitamin K antagonist) rather than UFH or LMWH in patients with remote HIT requiring VTE treatment or prophylaxis. B 8. Quality improvement Documentation: consider obtaining a hemostasis consultation within 3 months of the diagnosis of HIT and provide a card attesting this complication, specifying the results of the biological tests, and recommending the exclusion of all heparin treatment to the patient. E Medical alert bracelet: Consider offering carrying or wearing an emergency identifier (such as an emergency pendant or bracelet) in patients with a history of HIT in the past 3 months. C Avoid offering carrying or wearing an emergency identifier in patients with a history of HIT > 3 months ago. D References 1. Lori-Ann Linkins, Antonio L Dans, Lisa K Moores et al. Treatment and prevention of heparin-induced thrombocytopenia: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb;141 2 Suppl):e495S- e530S. Open 2. Adam Cuker, Gowthami M Arepally, Beng H Chong et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: heparin-induced thrombocytopenia. Blood Adv. 2018 Nov 27;2 22 3360 3392. Open 3. Yves Gruel, Emmanuel De Maistre, Claire Pouplard et al. Diagnosis and management of heparin-induced thrombocytopenia. Anaesth Crit Care Pain Med. 2020 Apr;39 2 291 310. Open 4. Jennifer S Lawton, Jacqueline E Tamis-Holland, Sripal Bangalore et al. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022 Jan 18;145 3):e18-e114. Open https://web.pathway.md/diseases/recR76V6DESBdk0f1 13/14 6/24/23, 12:31 PM Heparin-induced thrombocytopenia Pathway 5. Henry Watson, Simon Davidson, David Keeling et al. Guidelines on the diagnosis and management of heparin-induced thrombocytopenia: second edition. Br J Haematol. 2012 Dec;159 5 528 40. Open 6. J C Easaw, M A Shea-Budgell, C M J Wu et al. Canadian consensus recommendations on the management of venous thromboembolism in patients with cancer. Part 2 treatment. Curr Oncol. 2015 Apr;22 2 144 55. Open 7. Elliot L Chaikof, Ronald L Dalman, Mark K Eskandari et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg. 2018 Jan;67 1 2 77.e2. Open 8. Arif Khwaja. KDIGO clinical practice guidelines for acute kidney injury. Nephron Clin Pract. 2012;120 4):c179 84. Open 9. Miguel Sousa-Uva, Franz-Josef Neumann, Anders Ahlsson et al. 2018 ESC/EACTS Guidelines on myocardial revascularization. Eur J Cardiothorac Surg. 2019 Jan 1;55 1 4 90. Open 10. Wong GC, Welsford M, Ainsworth C et al. 2019 Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology Guidelines on the Acute Management of ST Elevation Myocardial Infarction: Focused Update on Regionalization and Reperfusion. Can J Cardiol. 2019 Feb;35 2 107 132. Open 11. Chan WS, Rey E, Kent NE et al. Venous thromboembolism and antithrombotic therapy in pregnancy. J Obstet Gynaecol Can. 2014 Jun;36 6 527 53. Open 12. Borja Ibanez, Stefan James, Stefan Agewall et al. 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology ESC . Eur Heart J. 2018 Jan 7;39 2 119 177. Open 13. American Society of Hematology. Choosing Wisely ASH recommendations. Choosing Wisely. 2014. Open 14. Mark Andrew Crowther, Deborah J Cook, Martin Albert et al. The 4Ts scoring system for heparin- induced thrombocytopenia in medical-surgical intensive care unit patients. J Crit Care. 2010 Jun;25 2 287 93. Open 15. Steven Coutre, MDMark Crowther, MD et al. Management of heparin-induced thrombocytopenia. UpToDate.Management of heparin-induced thrombocytopenia.2021. Open 16. Anand Padmanabhan, Laura Connelly-Smith, Nicole Aqui et al. Guidelines on the Use of Therapeutic Apheresis in Clinical Practice Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue. J Clin Apher. 2019 Jun;34 3 171 354. Open https://web.pathway.md/diseases/recR76V6DESBdk0f1 14/14