This is the current release of the guideline.

The rating scheme is defined at the end of the "Major Recommendations" field.

Recognition of Heparin-Induced Thrombocytopenia (HIT)

Platelet Count Monitoring for HIT

1. For patients receiving heparin in whom the risk of HIT is considered to be >0.1%, the guideline developers recommend platelet count monitoring over no platelet count monitoring (Grade 1C).

   Underlying values and preferences: This recommendation places a high value on diagnosis and early treatment of HIT to prevent sequelae and a lower value on the burden and cost of monitoring platelet counts.

Platelet Count Monitoring of Patients Recently Treated with Heparin

1. For patients who are starting unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) treatment and who have received UFH within the past 100 days, or those patients in whom exposure history is uncertain, the guideline developers suggest obtaining a baseline platelet count and then a repeat platelet count within 24 hours of starting heparin (Grade 2C).

Acute Systemic Reactions after Intravenous (IV) UFH Bolus

1. For patients who acquire acute inflammatory, cardiorespiratory, neurologic, or other unusual symptoms and signs within 30 min following an IV UFH bolus, the guideline developers recommend performing an immediate platelet count measurement, and comparing this value to recent prior platelet counts, in comparison with not performing a platelet count measure(Grade 1C).

Platelet Count Monitoring in Patients Receiving Therapeutic-Dose UFH

1. For patients who are receiving therapeutic-dose UFH, the guideline developers suggest at least every-other-day platelet count monitoring until day 14, or until UFH is stopped, whichever occurs first (Grade 2C).

   Underlying values and preferences: This recommendation places a high value on diagnosis and early treatment of HIT to prevent sequelae, and a lower value on the burden and cost of monitoring platelet counts.

Platelet Count Monitoring in Postoperative Patients Receiving UFH Antithrombotic Prophylaxis

1. For patients who are receiving postoperative antithrombotic prophylaxis with UFH (HIT risk >1%), the guideline developers suggest at least every-other-day platelet count monitoring between postoperative days 4 to 14, or until UFH is stopped, whichever occurs first (Grade 2C).

   Underlying values and preferences: This recommendation places a high value on diagnosis and early treatment of HIT to prevent sequelae, and a lower value on the burden and cost of monitoring platelet counts.

Platelet Count Monitoring in Patients in Whom HIT is Infrequent (0.1 to 1%)

1. For medical/obstetrical patients who are receiving prophylactic-dose UFH, postoperative patients receiving prophylactic-dose LMWH, postoperative patients receiving intravascular catheter UFH "flushes," or medical/obstetrical patients receiving LMWH after first receiving UFH (HIT risk 0.1 to 1%), the guideline developers suggest platelet count monitoring every 2 to 3 days from day 4 to day 14 (or until heparin is stopped, whichever occurs first), when practical (Grade 2C).

   Underlying values and preferences: This recommendation places a high value on diagnosis and early treatment of HIT to prevent sequelae, and a lower value on the burden and cost of monitoring platelet counts.

Platelet Count Monitoring When HIT is Rare (<0.1%)

1. For medical/obstetrical patients who are only receiving LMWH, or medical patients who are receiving only intravascular catheter UFH flushes (HIT risk <0.1%), the guideline developers suggest clinicians do not use routine platelet count monitoring (Grade 2C).

   Underlying values and preferences: This recommendation places a lower value on the rare diagnosis and early treatment of HIT to prevent sequelae, and a higher value on the burden and cost of monitoring platelet counts.

Screening for Subclinical HIT Antibody Seroconversion

1. In patients who receive heparin, the guideline developers recommend against routine HIT antibody testing in the absence of thrombocytopenia, thrombosis, heparin-induced skin lesions, or other sequelae of HIT (Grade 1C).

When Should HIT Be Suspected?

1. For patients receiving heparin, or who have received heparin within the previous 2 weeks, the guideline developers recommend excluding a diagnosis of HIT if the platelet count falls by >50%, and/or a thrombotic event occurs, between days 4 to 14 following initiation of heparin, even if the patient is no longer receiving heparin therapy when thrombosis or thrombocytopenia have occurred (Grade 1C).

Special Situation: Anticoagulant Prophylaxis and Platelet Count Monitoring after Cardiac Surgery

1. For postoperative cardiac surgery patients, the guideline developers recommend excluding a diagnosis of HIT if the platelet count falls by >50% (and/or a thrombotic event occurs) between postoperative days 4 to day 14 (day of cardiac surgery = day zero) [Grade 1C].

Treatment of HIT

Nonheparin Anticoagulants for HIT

1. For patients with strongly suspected (or confirmed) HIT, whether or not complicated by thrombosis, the guideline developers recommend use of an alternative, nonheparin anticoagulant, such as lepirudin (Grade 1C+), argatroban (Grade 1C), bivalirudin (Grade 2C), or danaparoid (Grade 1B), over further UFH or LMWH therapy, and over no further anticoagulation (with or without vena caval filter).
2. For patients with strongly suspected (or confirmed) HIT, whether or not there is clinical evidence of lower-limb deep vein thrombosis (DVT), the guideline developers recommend routine ultrasonography of the lower-limb veins for investigation of DVT, over not performing routine ultrasonography (Grade 1C).

Vitamin K Antagonists (VKAs)

Management of Direct Thrombin Inhibitor (DTI)-VKA Overlap

1. For patients with strongly suspected or confirmed HIT, the guideline developers recommend against the use of vitamin K antagonist (coumarin) therapy until after the platelet count has substantially recovered (e.g., to at least 100 x 10⁹/L, and preferably, 150 x 10⁹/L); that the VKA be administered only during overlapping alternative anticoagulation (minimum 5-day overlap), and begun with low, maintenance doses (maximum, 5 mg of warfarin, and 6 mg of phenprocoumon); that the alternative anticoagulant not be stopped until the platelet count has reached a stable plateau, and with at least the last 2 days the international normalized ration (INR) within the target therapeutic range (Grade 1C).

Reversal of VKA Anticoagulation

1. For patients receiving VKAs at the time of diagnosis of HIT, the guideline developers recommend use of vitamin K (Grade 2C).

LMWH for HIT

1. For patients with strongly suspected HIT, whether or not complicated by thrombosis, the guideline developers recommend against use of LMWH (Grade 1C+).

Prophylactic Platelet Transfusions for HIT

1. For patients with strongly-suspected or confirmed HIT who do not have active bleeding, the guideline developers suggest that prophylactic platelet transfusions not be administered (Grade 2C).

Special Patient Populations

Patients with Previous HIT Undergoing Cardiac or Vascular Surgery

1. For patients with a history of HIT who are HIT antibody negative and require cardiac surgery, the guideline developers recommend the use of UFH over a nonheparin anticoagulant (Grade 1C).

   Remark: Preoperative and postoperative anticoagulation, if indicated, should be administered with a nonheparin anticoagulant.

Patients with Acute or Subacute HIT Undergoing Cardiac Surgery

1. For patients with acute HIT (thrombocytopenic, HIT antibody positive) who require cardiac surgery, the guideline developers recommend one of the following alternative anticoagulant approaches (in descending order of preference):
   • Delaying surgery (if possible) until HIT antibodies are negative (see recommendation above concerning patients with previous HIT undergoing cardiac or vascular surgery) (Grade 1C);
   • Using bivalirudin for intraoperative anticoagulation during cardiopulmonary bypass (CPB) (if ecarin clotting time [ECT] available) (Grade 1C) or during off-pump cardiac surgery (Grade 1C+);
   • Using lepirudin for intraoperative anticoagulation (if ECT available and patient has normal renal function) (Grade 1C);
   • Using UFH plus the antiplatelet agent, epoprostenol (if ECT monitoring not available or renal insufficiency precludes lepirudin use) (Grade 2C);
   • Using UFH plus the antiplatelet agent, tirofiban (Grade 2C);
   • Using danaparoid for intraoperative anticoagulation (if anti-factor Xa levels are available) (Grade 2C)
2. For patients with subacute HIT (platelet count recovery, but continuing HIT antibody-positive), the guideline developers recommend delaying surgery (if possible) until HIT antibodies are negative, then using heparin (see recommendation above concerning patients with previous HIT undergoing cardiac or vascular surgery) (Grade 1C). Alternatively, the guideline developers suggest the use of a nonheparin anticoagulant (see recommendation directly above concerning patients with acute HIT [thrombocytopenic, HIT antibody positive] who require cardiac surgery) (Grade 2C).

Percutaneous Coronary Interventions (PCIs)

1. For patients with acute or previous HIT who require cardiac catheterization or PCI, the guideline developers recommend use of an alternative anticoagulant, such as argatroban (Grade 1C), bivalirudin (Grade 1C), lepirudin (Grade 1C), or danaparoid (Grade 2C), over the use of heparin.

Prevention of HIT

Reducing HIT Antibody Formation and Clinical HIT

UFH vs. LMWH

1. For postoperative orthopedic surgery patients, the guideline developers recommend the use of LMWH over UFH (Grade 1A).

Bovine vs. Porcine UFH

1. For the treatment of patients with thrombosis, the guideline developers recommend against the use of bovine UFH, in comparison with porcine UFH or LMWH (Grade 1A).
2. For patients undergoing cardiac surgery, the guideline developers recommend the use of porcine UFH for intraoperative anticoagulation, in comparison with bovine UFH (Grade 1B).

Definitions

*These situations include RCTs with both lack of blinding and subjective outcomes, where the risk of bias in measurement of outcomes is high, or RCTs with large loss to follow-up.

None provided

The type of supporting evidence is identified and graded for each recommendation (see "Major Recommendations").

Not applicable: The guideline was not adapted from another source.

2004 Sep

American College of Chest Physicians - Medical Specialty Society

Funding was provided through an unrestricted educational grant by AstraZeneca LP, Aventis Pharmaceuticals, GlaxoSmithKline, Bristol-Myer Squibb/Sanofi-Synthelabo Partnership, and Organon Sanofi-Synthelabo LLC.

American College of Chest Physicians Consensus Panel on Antithrombotic and Thrombolytic Therapy

Primary Authors: Theodore E. Warkentin, MD (Chair); Andreas Greinacher, MD

Dr. Warkentin has received research funding from Organon and Sanofi-Synthelabo, and has received honoraria for his participation on advisory boards and/or as a speaker at educational events from Aventis, Berlex Laboratories, Genentech, Glaxo Smith Kline, Medicines Company, Novartis, NovoNordisk, Organon, Pharmion, RenalTech International, and Sanofi-Synthelabo.

Dr. Greinacher has received research funding from Celltech, Berlex, Pharmion, Novartis, and has received honoraria for his participation on advisory boards and/or as a speaker at educational events from Berlex, Pharmion, Celltech, Mitsubishi, Aventis Pharma, SheringAG.

This is the current release of the guideline.

This NGC summary was completed by ECRI on November 19, 2004. The information was verified by the guideline developer on January 12, 2005. This summary was updated by ECRI on March 6, 2007 following the U.S. Food and Drug Administration (FDA) advisory on Coumadin (warfarin sodium). This summary was updated by ECRI Institute on June 22, 2007 following the U.S. Food and Drug Administration (FDA) advisory on heparin sodium injection. This summary was updated by ECRI Institute on September 7, 2007 following the revised U.S. Food and Drug Administration (FDA) advisory on Coumadin (warfarin). This summary was updated by ECRI Institute on March 14, 2008 following the updated FDA advisory on heparin sodium injection.

This NGC summary is based on the original guideline, which is subject to the guideline developer's copyright restrictions.