Heparin-Induced Heparin-Induced Thrombocytopenia Thrombocytopenia (HIT): Pathophysiology, (HIT): Pathophysiology, Clinical Implications, Clinical Implications, Therapy, and Cases Therapy, and Cases Jerrold H Levy, MD Jerrold H Levy, MD Emory University School of Emory University School of Medicine Medicine Atlanta, Georgia Atlanta, Georgia ARG266R0
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Heparin-Induced Thrombocytopenia (HIT): Pathophysiology, Clinical Implications, Therapy, and Cases Jerrold H Levy, MD Emory University School of Medicine.
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Heparin-Induced ThrombocytopeniaHeparin-Induced Thrombocytopenia(HIT): Pathophysiology, Clinical (HIT): Pathophysiology, Clinical Implications, Therapy, and CasesImplications, Therapy, and Cases
Jerrold H Levy, MDJerrold H Levy, MDEmory University School of MedicineEmory University School of Medicine
Atlanta, GeorgiaAtlanta, Georgia
ARG266R0
Slide 2
HITHIT Immune-mediated allergic reaction to heparin/platelet Immune-mediated allergic reaction to heparin/platelet
factor 4 complexfactor 4 complex
Thrombocytopenia Thrombocytopenia – Platelet count <150,000 thrombocytes/mcL or a 30% to 50% Platelet count <150,000 thrombocytes/mcL or a 30% to 50%
drop from baseline during heparin exposuredrop from baseline during heparin exposure– Onset 5 to 14 days after initiating heparin but can be earlier or Onset 5 to 14 days after initiating heparin but can be earlier or
laterlater
With or without thrombotic complications at With or without thrombotic complications at presentationpresentation
Diagnosis is clinicalDiagnosis is clinical
Any type of heparin or route of administration can Any type of heparin or route of administration can lead to HITlead to HIT
Kelton. Kelton. Semin Hematol.Semin Hematol. 1999;36(suppl 1):17-21; Matthai. 1999;36(suppl 1):17-21; Matthai. Semin Thromb HemostSemin Thromb Hemost. . 1999;25(suppl 1):57-60; Rice et al. 1999;25(suppl 1):57-60; Rice et al. Ann Intern MedAnn Intern Med. 2002;136(3):210-215. Greinacher et al. . 2002;136(3):210-215. Greinacher et al. Thrombosis ResearchThrombosis Research. 2005 In Press.. 2005 In Press.
Slide 3
Incidence of HITIncidence of HIT
HIT occurs in up to 5% of patients HIT occurs in up to 5% of patients receiving unfractionated heparin receiving unfractionated heparin (UFH) (UFH)
Up to 1% incidence with low molecular Up to 1% incidence with low molecular weight heparin (LMWH)weight heparin (LMWH)
If left untreated, the overall risk of If left untreated, the overall risk of thrombosis is 38% to 76% in HIT patients thrombosis is 38% to 76% in HIT patients based on 3 studies (n=425)based on 3 studies (n=425)
Based on increased morbidity and mortality, Based on increased morbidity and mortality, heparin cessation alone is inadequateheparin cessation alone is inadequate
38% to 52% of HIT patients managed by 38% to 52% of HIT patients managed by heparin cessation alone developed heparin cessation alone developed thrombotic complications, including DVT, thrombotic complications, including DVT, PE, stroke, or MI within 1 monthPE, stroke, or MI within 1 month
Since thrombotic events have been observed Since thrombotic events have been observed even after cessation of heparin exposure, even after cessation of heparin exposure, early recognition and initiation of appropriate early recognition and initiation of appropriate therapy are essential steps in managementtherapy are essential steps in management
Levine et al. Levine et al. Ann Emer MedAnn Emer Med. 2004;44:511-515. 2004;44:511-515. . Adapted from Parker. Adapted from Parker. J Crit Ill. J Crit Ill. 2005’20(3):64-71.2005’20(3):64-71.
Slide 10
Consequences of HIT Consequences of HIT
Mortality rate of 22% to 28% has been Mortality rate of 22% to 28% has been reported in patients with HIT associated with reported in patients with HIT associated with thrombosis not treated with alternative thrombosis not treated with alternative anticoagulation.anticoagulation.
Levine et al. Levine et al. Ann Emer Med. Ann Emer Med. 2004;44:511-515.2004;44:511-515.
Slide 11
HIT Patients Presenting with ThrombosisHIT Patients Presenting with Thrombosis Deep venous thrombosis (50%)Deep venous thrombosis (50%)
Pulmonary embolism (25%) Pulmonary embolism (25%)
Skin lesions at injection site (10% to 20%)Skin lesions at injection site (10% to 20%)
Acute limb ischemia (5% to 10%)Acute limb ischemia (5% to 10%)
Warfarin-associated venous limb gangrene Warfarin-associated venous limb gangrene (5% to 10%)(5% to 10%)
Acute thrombotic stroke or myocardial infarction Acute thrombotic stroke or myocardial infarction (3% to 5%)(3% to 5%)
Acute systemic reactions following IV bolus Acute systemic reactions following IV bolus (~25%)(~25%)
Fc receptorFc receptormicroparticlesmicroparticles
PlateletPlatelet
Courtesy of Dr John G. Kelton, McMaster UniversityCourtesy of Dr John G. Kelton, McMaster University .. Hirsh et al. Hirsh et al. Arch Intern MedArch Intern Med. 2004;164:361-369. 2004;164:361-369..
Slide 13
Clinical Diagnosis of HITClinical Diagnosis of HIT
Timing of thrombocytopeniaTiming of thrombocytopenia– 5 to 14 days after initiation of heparin, except in 5 to 14 days after initiation of heparin, except in
patients with recent heparin exposure patients with recent heparin exposure
– Earlier onset of thrombocytopenia with heparin Earlier onset of thrombocytopenia with heparin
re-exposurere-exposure
– Onset may be delayed and may can occur weeks to Onset may be delayed and may can occur weeks to months after heparin discontinuationmonths after heparin discontinuation
Degree of thrombocytopeniaDegree of thrombocytopenia– Decrease from baseline of 30% to 50%Decrease from baseline of 30% to 50%
– 10% to 15% of HIT patients will have platelet count WNL10% to 15% of HIT patients will have platelet count WNL
Other causes of thrombocytopenia excludedOther causes of thrombocytopenia excludedRice et al. Rice et al. Ann Intern MedAnn Intern Med. 2002:136(3):210-215;. 2002:136(3):210-215; Warkentin. Warkentin. Thromb Haemost.Thromb Haemost. 1999;82:439-447; 1999;82:439-447; Warkentin. Warkentin. Semin HematolSemin Hematol. 1998;35(suppl 5):9-16.. 1998;35(suppl 5):9-16.
Slide 14
Temporal Patterns of Thrombocytopenia in HIT
Day 1 Day 5 Day 14 Day 30
Delayed-Onset HIT
(9-40+ days)
Rapid-onset HIT
(hours-days)
Typical-Onset HITMean day 9(5-14 days)
Heparin (re) Exposure
THROMBOCYTOPENIA (± THROMBOSIS)
Warkentin TE et al. Warkentin TE et al. ChestChest. 2004;126(3 suppl):311S-337S. . 2004;126(3 suppl):311S-337S. Rice et al. Ann Intern Med. 2002;136(3):210-215. Warkentin et al. Ann Intern Med. 2001;135:502-506. Warkentin et al. NEJM. 2001;344(17):1286-92. DeEugenio DL, et al. Pharmacotherapy. 2005;25:615-619. Courtesy of Dr Ahjad AlMahameed, Cleveland Clinic, OH
Slide 15
Distribution of Platelet Count in HITDistribution of Platelet Count in HIT
Use of intra-aortic ballon pumpUse of intra-aortic ballon pumpAird AC, Mark EJ. Aird AC, Mark EJ. N Engl J MedN Engl J Med. 2002;346:1562-1570.. 2002;346:1562-1570.
Slide 19
SRASRA Sensitivity: high Sensitivity: high Technically demandingTechnically demandingSpecificity: highSpecificity: high (radioisotopes) (radioisotopes) (false (false positives rare) positives rare) Not readily availableNot readily available
Platelet (HIPA)Platelet (HIPA) Specificity: high Specificity: high Sensitivity: lowSensitivity: low aggregationaggregation Technique-dependentTechnique-dependent
ImmunoassayImmunoassay Sensitivity: high Sensitivity: high Specificity: low (falseSpecificity: low (false (ELISA)(ELISA) Technically easy Technically easy positives common for positives common for
Rapid turnaround time Rapid turnaround time some populations)some populations)
PIFAPIFA®® Sensitivity: highSensitivity: high Limited clinical historyLimited clinical history Specificity: highSpecificity: high Positive & NegativePositive & Negative Technically easyTechnically easy controls not providedcontrols not provided Rapid Rapid
turnaround timeturnaround time with assaywith assay
TestTest AdvantagesAdvantages Disadvantages DisadvantagesLaboratory Testing for HITLaboratory Testing for HIT
HIT Requires a Clinical HIT Requires a Clinical DiagnosisDiagnosis SRA=serotonin-release assay; ELISA=enzyme-linked immunosorbent assay.SRA=serotonin-release assay; ELISA=enzyme-linked immunosorbent assay.
Diagnosis and Management Diagnosis and Management Decisions for HITDecisions for HIT
Current or recent heparin exposure with Current or recent heparin exposure with thrombocytopeniathrombocytopenia
Presence of thrombosis or other Presence of thrombosis or other characteristic sequelaecharacteristic sequelae
If HIT is suspected, discontinue all forms If HIT is suspected, discontinue all forms of heparin IMMEDIATELY: Initiate of heparin IMMEDIATELY: Initiate alternative anticoagulant,alternative anticoagulant, as indicatedas indicated
Prophylaxis and Treatment of HIT:Prophylaxis and Treatment of HIT:Patient Risk FactorsPatient Risk Factors
HIT with/without thrombosis should be suspected HIT with/without thrombosis should be suspected in patients with a 30% to 50% drop in platelets andin patients with a 30% to 50% drop in platelets and– Heparin use Heparin use
– History of HITHistory of HIT
– Recent exposure to heparin Recent exposure to heparin
– Surgery Surgery Venous thrombosis: more common in orthopedic surgeryVenous thrombosis: more common in orthopedic surgery Arterial thrombosis: more common in cardiac proceduresArterial thrombosis: more common in cardiac procedures
Boshkov et al. Boshkov et al. Br J Haematol.Br J Haematol. 1993;84:322-328; Hirsh et al. 1993;84:322-328; Hirsh et al. Arch Intern MedArch Intern Med. 2004;164:361-. 2004;164:361-369;369; Spencer. Spencer. J Thromb ThrombolysisJ Thromb Thrombolysis. 2000;10(suppl 1):21-25; Warkentin and Kelton. . 2000;10(suppl 1):21-25; Warkentin and Kelton. Am J Am J MedMed. 1996;101:502-507; Warkentin et al. . 1996;101:502-507; Warkentin et al. N Engl J Med.N Engl J Med. 1995;332:1330-1335. 1995;332:1330-1335.
Slide 22
Treatment Goals Based on Pathophysiology Treatment Goals Based on Pathophysiology and Clinical Studiesand Clinical Studies
Interrupt the immune responseInterrupt the immune response– Discontinue heparinDiscontinue heparin
Inhibit thrombin generationInhibit thrombin generation– Treat active thrombosisTreat active thrombosis
– Prevent new thrombosisPrevent new thrombosis
Minimize complications of HITMinimize complications of HIT– Thromboses, limb amputation, deathThromboses, limb amputation, death
Slide 23
Mechanisms of Thrombin InhibitionMechanisms of Thrombin Inhibition
Saito H. Disorders of Hemostasis. 3rd ed. 1996;2:23-52.
Slide 24
Direct Thrombin Inhibitors: Direct Thrombin Inhibitors: Mechanism of ActionMechanism of Action
Directly inhibit procoagulant and prothrombotic Directly inhibit procoagulant and prothrombotic actions of thrombinactions of thrombin
Do not require a cofactor to inhibit thrombinDo not require a cofactor to inhibit thrombin
Active against both free and clot-bound Active against both free and clot-bound thrombinthrombin
Do not interact with or produce heparin-Do not interact with or produce heparin-dependent antibodiesdependent antibodies
AngiomaxAngiomax®® (bivalirudin) for Injection [package insert]. The Medicines Company; 2004; (bivalirudin) for Injection [package insert]. The Medicines Company; 2004; Argatroban Injection [package insert]. GlaxoSmithKline; 2005; Chen. Argatroban Injection [package insert]. GlaxoSmithKline; 2005; Chen. Heart Dis.Heart Dis. 2001;3:189- 2001;3:189-198; Refludan198; Refludan®® [lepirudin (rDNA) for injection] [lepirudin (rDNA) for injection] [package insert]. Berlex Laboratories; 2004.[package insert]. Berlex Laboratories; 2004.
Slide 25
Potential Benefits of Potential Benefits of Direct Thrombin InhibitorsDirect Thrombin Inhibitors
aPTT = activated partial thromboplastin time; ACT = activated clotting time.Adapted from Chen JL. Heart Dis. 2001;3:189-198. Warkentin, TE, Greinacher A. Heparin-Induced Thrombocytopenia. 3rd ed. Revised and Expanded. 2004;:339-479.Warkentin TE, Greinacher A. Chest 2004;126:311s–337s.
Argatroban Lepirudin Bivalirudin
Slide 27
Direct Thrombin Inhibitors: Direct Thrombin Inhibitors: FDA Indications and UsageFDA Indications and Usage
ArgatrobanArgatroban– Indicated as an anticoagulant for prophylaxis or treatment of Indicated as an anticoagulant for prophylaxis or treatment of
thrombosis in patients with HITthrombosis in patients with HIT
– Indicated as an anticoagulant in patients with or Indicated as an anticoagulant in patients with or at risk for HIT undergoing PCIat risk for HIT undergoing PCI
LepirudinLepirudin– Indicated for anticoagulation in patients with HIT and Indicated for anticoagulation in patients with HIT and
associated thromboembolic disease to prevent further associated thromboembolic disease to prevent further thromboembolic complications thromboembolic complications
Bivalirudin*Bivalirudin*– Indicated as an anticoagulant in patients undergoing Indicated as an anticoagulant in patients undergoing
*Recently approved for with or at risk HIT patients undergoing PCI. (Dec. 2005)*Recently approved for with or at risk HIT patients undergoing PCI. (Dec. 2005)
AngiomaxAngiomax®® (bivalirudin) for injection [package insert]. Parsippany, NJ: The Medicines Company; 2005; (bivalirudin) for injection [package insert]. Parsippany, NJ: The Medicines Company; 2005; Argatroban Injection [package insert]. Research Triangle Park, NC: GlaxoSmithKline; 2005; RefludanArgatroban Injection [package insert]. Research Triangle Park, NC: GlaxoSmithKline; 2005; Refludan®® [lepirudin (rDNA) for Injection] [package insert]. Montvale, NJ: Berlex Laboratories, Inc.; 2004.[lepirudin (rDNA) for Injection] [package insert]. Montvale, NJ: Berlex Laboratories, Inc.; 2004.
Slide 28
The Seventh ACCP Conference on The Seventh ACCP Conference on Antithrombotic and Thrombolytic Antithrombotic and Thrombolytic
Routine ultrasonography of lower limb Routine ultrasonography of lower limb veins should be performed to evaluate veins should be performed to evaluate thrombosisthrombosis
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Slide 31
Grade 1C+ : Do not useGrade 1C+ : Do not useACCP recommends strongly ACCP recommends strongly AGAINSTAGAINST use of vitamin K antagonists use of vitamin K antagonists
CoumadinCoumadin® ® until after platelet count has recovered (100,000-until after platelet count has recovered (100,000-150,000/mcL)150,000/mcL)
Vitamin K antagonists should be administered only during Vitamin K antagonists should be administered only during overlap with alternative anticoagulationoverlap with alternative anticoagulation
Begin with low, maintenance doses (maximum 5 mg warfarin; Begin with low, maintenance doses (maximum 5 mg warfarin; 6 mg phenprocoumon)6 mg phenprocoumon)
Alternative anticoagulants should not be Alternative anticoagulants should not be STOPPED STOPPED until platelet until platelet count has reached a stable plateau and with at least the last 2 count has reached a stable plateau and with at least the last 2 days of INR within target therapeutic rangedays of INR within target therapeutic range
ACCP Guidelines: HITACCP Guidelines: HIT
CoumadinCoumadin®® (Warfarin Sodium for Injection, USP) [package insert]. Princeton, NJ: Bristol-Myers (Warfarin Sodium for Injection, USP) [package insert]. Princeton, NJ: Bristol-Myers Squibb Company; 2005. Squibb Company; 2005. Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Slide 32
ACCP Guidelines: HITACCP Guidelines: HIT
Grade 2C: Very weak recommendationGrade 2C: Very weak recommendation
ACCP recommends for patients receiving ACCP recommends for patients receiving vitamin K antagonist therapy at the time vitamin K antagonist therapy at the time of diagnosis, reversal of vitamin K of diagnosis, reversal of vitamin K antagonism by use of oral or IV vitamin Kantagonism by use of oral or IV vitamin K
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Slide 33
ACCP Guidelines: Acute or Previous HIT in ACCP Guidelines: Acute or Previous HIT in Patients Who Require Catheterization or PCIPatients Who Require Catheterization or PCI
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Slide 34
Grade 1C+: Do not useGrade 1C+: Do not use
ACCP recommends strongly ACCP recommends strongly AGAINSTAGAINST use use of lowof low––molecular-weight heparins in HIT molecular-weight heparins in HIT patientspatients
Grade 2C: Do not useGrade 2C: Do not use
ACCP recommends ACCP recommends AGAINSTAGAINST prophylactic prophylactic platelet transfusions for patients who do platelet transfusions for patients who do not have active bleedingnot have active bleeding
ACCP Guidelines: HITACCP Guidelines: HIT
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Slide 35
2004 ACCP Summary of Recommendations for HIT2004 ACCP Summary of Recommendations for HIT
DanaparoidDanaparoid 1B1B 1B1B
ArgatrobanArgatroban 1C1C 1C1C
LepirudinLepirudin 1C+1C+ 1C+1C+
BivalirudinBivalirudin 2C2C 2C2C
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
Prophylaxis Prophylaxis thrombosis in thrombosis in
HITHIT
TreatmentTreatment thrombosis in thrombosis in
HITHIT
Slide 36
2004 ACCP Summary of Recommendations 2004 ACCP Summary of Recommendations for HITfor HIT
Acute HITAcute HIT
LMWHLMWH Do not use 1C+Do not use 1C+
VKAVKA Do not use 1CDo not use 1C
Platelet transfusionPlatelet transfusion Do not use 2CDo not use 2C
Warkentin TE et al. Warkentin TE et al. Chest.Chest. 2004;126(3 suppl):311S-337S. 2004;126(3 suppl):311S-337S.
LMWH = low–molecular-weight heparin; VKA = vitamin K antagonists.
HIT CASE STUDIESHIT CASE STUDIES
Slide 38
HIT CASE STUDY - Patient #1HIT CASE STUDY - Patient #1
45 yo F Stage IB Endometrial Carcinoma45 yo F Stage IB Endometrial Carcinoma
TAH, BSO, LND TAH, BSO, LND
Received prophylactic post op IV heparin x 4 daysReceived prophylactic post op IV heparin x 4 days
Post-op Day 6 - chest pain and SOB, collapsed, cyanoticPost-op Day 6 - chest pain and SOB, collapsed, cyanotic
VQ scan (+) for PE & 5mm thrombosis @ tip of CVCVQ scan (+) for PE & 5mm thrombosis @ tip of CVC
IV Heparin re-initiated + urokinase given for thrombolysis IV Heparin re-initiated + urokinase given for thrombolysis with initial improvement in signs and symptomswith initial improvement in signs and symptoms
Post-op Day 9 - sudden PLT drop 238,000 to 39,000mcLPost-op Day 9 - sudden PLT drop 238,000 to 39,000mcL
HIT suspected, heparin d/c'dHIT suspected, heparin d/c'd
Aida H, Aoki Y, Ohki I, & Tanaka K. Anticoagulation with a selective thrombin inhibitor in a woman with heparin-induced thrombocytopenia. Obstet Gynecol. 2001;98:952-954.
Slide 39
HIT CASE STUDY - Patient #1 HIT CASE STUDY - Patient #1 (cont'd)(cont'd)
POD 10, CVC thrombus larger. Underwent successful POD 10, CVC thrombus larger. Underwent successful thrombectomythrombectomy
Argatroban was administered intra- and postoperativelyArgatroban was administered intra- and postoperatively
PLT post-op Day 1 - 104,000/mcL PLT post-op Day 1 - 104,000/mcL
Oral warfarin and ASA initiatedOral warfarin and ASA initiated
PLT post-op Day 4 - 236,000/mcL PLT post-op Day 4 - 236,000/mcL
Patient was discharged home without further complications Patient was discharged home without further complications on hospital Day 32on hospital Day 32
Case based on an actual patient. Individual results may vary.Case based on an actual patient. Individual results may vary.
Aida H, Aoki Y, Ohki I, & Tanaka K. Anticoagulation with a selective thrombin inhibitor in a woman with heparin-induced thrombocytopenia. Obstet Gynecol. 2000;98:952-954.
Lab findingsLab findings– elevated IgG antibody by elevated IgG antibody by
immunoassayimmunoassay
Aida H, Aoki Y, Ohki I, & Tanaka K. (2001). Anticoagulation with a selective thrombin inhibitor in a woman with heparin-induced thrombocytopenia. Obstet Gynecol. 2001;98:952-954.
Slide 41
HIT CASE STUDY - Patient #2HIT CASE STUDY - Patient #2
60 yo female underwent repair of aortic aneurysm with 60 yo female underwent repair of aortic aneurysm with aortic valve replacement. aortic valve replacement.
She received LMWH 30mg SQ bid from POD 1 through 6 She received LMWH 30mg SQ bid from POD 1 through 6 followed by warfarin therapy upon D/Cfollowed by warfarin therapy upon D/C
POD 4 she experienced transient amnesia that was POD 4 she experienced transient amnesia that was attributed to medicationsattributed to medications
Re-presented to ED 33 days later after initial heparin Re-presented to ED 33 days later after initial heparin exposure with proximal-thigh DVT despite a INR of 4.2 exposure with proximal-thigh DVT despite a INR of 4.2
Patient admitted and IV heparin initiated in EDPatient admitted and IV heparin initiated in ED
Rice L, Attisha WK, Drexler, AD, Francis JL. Delayed-onset heparin-induced thrombocytopenia. Ann Intern Med. 2002;136(3):210-215.
Slide 42
HIT CASE STUDY - Patient #2 HIT CASE STUDY - Patient #2 (cont'd)(cont'd)
Immediately after receiving IV heparin bolus, she developed Immediately after receiving IV heparin bolus, she developed dyspnea, tachycardia & hypotension which required intubation dyspnea, tachycardia & hypotension which required intubation and mechanical ventilationand mechanical ventilation
An inferior vena cava filter was placed for suspected PEAn inferior vena cava filter was placed for suspected PE
PLT count was 420,000/mcL on readmission, but dropped to PLT count was 420,000/mcL on readmission, but dropped to 47,000/mcL after the heparin bolus47,000/mcL after the heparin bolus
VQ scan low probability for PE VQ scan low probability for PE
ELISA (+) for heparin antibodiesELISA (+) for heparin antibodies
Started on danaparoid* Started on danaparoid*
Patient D/C without further sequelae, PLT’s 343,000/mcLPatient D/C without further sequelae, PLT’s 343,000/mcL
Case based on an actual patient. Individual results may vary.Case based on an actual patient. Individual results may vary.*No longer available in the US.
Rice L, Attisha WK, Drexler, AD, Francis JL. Delayed-onset heparin-induced thrombocytopenia. Ann Intern Med. 2002;136(3):210-215.
Slide 43
HIT DIAGNOSIS - Patient #2HIT DIAGNOSIS - Patient #2 Onset of HITOnset of HIT
– HIT has been documented HIT has been documented to occur up to 40 days after to occur up to 40 days after heparin discontinuationheparin discontinuation
– Patient presented to the ED Patient presented to the ED with a DVT 33 days after with a DVT 33 days after initial exposureinitial exposure
Thrombotic complicationsThrombotic complications– venous vs arterial venous vs arterial
– Suspect transient amnesia Suspect transient amnesia during first hospitalization during first hospitalization was related to HITwas related to HIT
– New onset DVTNew onset DVT
Degree of PLT fallDegree of PLT fall– 10% to15% of patients with 10% to15% of patients with
HIT, PLT nadir is above HIT, PLT nadir is above 150,000/mcL 150,000/mcL
– Upon heparin re-exposure, Upon heparin re-exposure,
dramatic drop in PLT count dramatic drop in PLT count
420,000/mcL to 47,000/mcL 420,000/mcL to 47,000/mcL after bolusafter bolus
Delayed-onset HIT should be a Delayed-onset HIT should be a primary diagnostic primary diagnostic consideration whenever a consideration whenever a recently hospitalized patient recently hospitalized patient presents with presents with thromboembolismthromboembolism
Rice L, Attisha WK, Drexler, AD, Francis JL. Delayed-onset heparin-induced thrombocytopenia. Ann Intern Med. 2002;136(3):210-215.
Slide 44
HIT CASE STUDY - Patient #3HIT CASE STUDY - Patient #3
63 yo F w/ metastatic Ovarian Carcinoma63 yo F w/ metastatic Ovarian Carcinoma
Presented to clinic c/o (R) arm swellingPresented to clinic c/o (R) arm swelling
Hickman catheter placement 2 1/2 weeks prior to Hickman catheter placement 2 1/2 weeks prior to chemochemo
Received Cisplatin, Taxol, CTX Received Cisplatin, Taxol, CTX
Daily heparin saline flushes for 3 wksDaily heparin saline flushes for 3 wks
Day 10 after chemo PLT drop 329,000 to 73,000/mcLDay 10 after chemo PLT drop 329,000 to 73,000/mcL
At clinic visit, day 18, PLT continued to fall to At clinic visit, day 18, PLT continued to fall to 20,000/mcL with R subclavian vein thrombosis 20,000/mcL with R subclavian vein thrombosis documenteddocumented
Kadidal VV, Mayo DJ, Horne MK. Heparin-induced thrombocytopenia (HIT) due to heparin flushes: a report of three cases. J Int Med. 1999;246:325-329.
Slide 45
HIT CASE STUDY - Patient #3 HIT CASE STUDY - Patient #3 (cont'd)(cont'd)
PLT transfusion givenPLT transfusion given
IV heparin initiatedIV heparin initiated
Due to failure of PLT to rise, HIT was suspectedDue to failure of PLT to rise, HIT was suspected
Heparin was d/c'dHeparin was d/c'd
Danaparoid* was initiatedDanaparoid* was initiated
Pre-heparin ELISA and SRA assays were (+)Pre-heparin ELISA and SRA assays were (+)
PLT count rose >100,000mcL within 3 days while on PLT count rose >100,000mcL within 3 days while on danaparoid*danaparoid*
Case based on an actual patient. Individual results may vary.Case based on an actual patient. Individual results may vary.
*No longer available in the US.
Kadidal VV, Mayo DJ, Horne MK. Heparin-induced thrombocytopenia (HIT) due to heparin flushes: a report of three cases. J Int Med. 1999;246:325-329.
heparin flush, IV heparin flush, IV heparin, platelet heparin, platelet transfusiontransfusion
Patient factorsPatient factors– cancer, Hickman linecancer, Hickman line
Timing of PLT fallTiming of PLT fall– initial fall suspected to be chemo initial fall suspected to be chemo
nadir Day 10 nadir Day 10
– continuation of fall Day 18continuation of fall Day 18
Delayed onset HIT??Delayed onset HIT??
Degree of PLT fallDegree of PLT fall– 329,000 to 73,000 to 20,000/mcL329,000 to 73,000 to 20,000/mcL
– lack of response to transfusion lack of response to transfusion and IV heparinand IV heparin
Development of ThrombosisDevelopment of Thrombosis– subclavian vein thrombosissubclavian vein thrombosis
Laboratory findingsLaboratory findings– (+) ELISA and SRA(+) ELISA and SRA
Kadidal VV, Mayo DJ, Horne MK. Heparin-induced thrombocytopenia (HIT) due to heparin flushes: a report of three cases. J Int Med. 1999;246:325-329.
Slide 47
HIT CASE STUDY - Patient #4HIT CASE STUDY - Patient #4
75 yo male had infected knee prosthesis removed75 yo male had infected knee prosthesis removed
Received LMWH 30 mg SQ BID POD 1-9Received LMWH 30 mg SQ BID POD 1-9
Discharge Day 9Discharge Day 9
Readmitted Day 12 with swollen, dusky left arm, the Readmitted Day 12 with swollen, dusky left arm, the site of subclavian cathetersite of subclavian catheter
Rice L, Attisha WK, Drexler, AD, Francis JL. Delayed-onset heparin-induced thrombocytopenia. Ann Intern Med. 2002;136(3):210-215.
Slide 50
HIT CASE STUDY - Patient #5HIT CASE STUDY - Patient #5
67 y/o male had undergone coronary artery bypass surgery 67 y/o male had undergone coronary artery bypass surgery
POD 7 presented to ED with sudden onset of confusionPOD 7 presented to ED with sudden onset of confusion
CT scan revealed no intracranial hemorrhageCT scan revealed no intracranial hemorrhage
Diagnosed with left-sided cerebrovascular accidentDiagnosed with left-sided cerebrovascular accident
Intravenous heparin initiated in ED for possible Intravenous heparin initiated in ED for possible thromboembolic strokethromboembolic stroke
POD 7 PLT 233,000/mcLPOD 7 PLT 233,000/mcL
POD 9 PLT 84,000/mcLPOD 9 PLT 84,000/mcL
Heparin d/c’d due to suspicion of HITHeparin d/c’d due to suspicion of HIT
HIT antibody testing (+)HIT antibody testing (+)
Levine et al. Levine et al. Annals of Emergency MedicineAnnals of Emergency Medicine. 2004;44:511-515.. 2004;44:511-515.
Slide 51
HIT CASE STUDY - Patient #5 HIT CASE STUDY - Patient #5 (cont'd)(cont'd)
Neurologic status deterioratedNeurologic status deteriorated
Repeat CT scan showed large area of ischemia w/o bleedingRepeat CT scan showed large area of ischemia w/o bleeding
IV Argatroban initiated but d/c’d after 2 hoursIV Argatroban initiated but d/c’d after 2 hours
Concerns of possible intracranial bleedingConcerns of possible intracranial bleeding
Serial CT scans revealed no bleedingSerial CT scans revealed no bleeding
No further anticoagulant administeredNo further anticoagulant administered
During next 3 days patient remained unresponsive, developed During next 3 days patient remained unresponsive, developed multiple bilateral cerebral infarcts with clinical deteriorationmultiple bilateral cerebral infarcts with clinical deterioration
Withdrawal of life support and patient expiredWithdrawal of life support and patient expired
Case based on an actual patient. Individual results may vary.Case based on an actual patient. Individual results may vary.
Levine et al. Levine et al. Annals of Emergency MedicineAnnals of Emergency Medicine. 2004;44:511-515.. 2004;44:511-515.
Key to limiting early morbidity and mortality Key to limiting early morbidity and mortality from HIT is from HIT is – Rapid recognition of signs & symptomsRapid recognition of signs & symptoms
– Early identification with diligent PLT monitoringEarly identification with diligent PLT monitoring
– Avoid platelet transfusions except in major bleedingAvoid platelet transfusions except in major bleeding
– Immediate cessation of all heparin sourcesImmediate cessation of all heparin sources
– Initiation of alternate therapyInitiation of alternate therapy
Nurses & pharmacists play a vital role in the Nurses & pharmacists play a vital role in the early recognition of HIT by monitoring vigilantly early recognition of HIT by monitoring vigilantly for drops in platelet counts & new thrombotic for drops in platelet counts & new thrombotic events while patients are on heparinevents while patients are on heparin
For adjusted- and full-dose therapy, perform platelet For adjusted- and full-dose therapy, perform platelet counts pre-treatment and at least on alternate dayscounts pre-treatment and at least on alternate days
– Begin on day 4 for heparin-naïve patients Begin on day 4 for heparin-naïve patients
– Begin on day 1 for patents with prior heparin Begin on day 1 for patents with prior heparin
College of American Pathologists Consensus Arch Pathol Lab Med 1998;122:782–798.
Slide 56
Summary of HIT Summary of HIT HIT is a life- and limb-threatening medical HIT is a life- and limb-threatening medical
emergencyemergency
HIT is a relatively common and often under-HIT is a relatively common and often under-recognized devastating complication of heparin recognized devastating complication of heparin therapytherapy
However the consequences of HIT are largely However the consequences of HIT are largely preventable with early recognition and proper preventable with early recognition and proper treatment treatment
Awareness of the clinical presentation of HIT and Awareness of the clinical presentation of HIT and the ability to distinguish it from other causes of the ability to distinguish it from other causes of platelet count reduction are keys to avoiding platelet count reduction are keys to avoiding serious sequelaeserious sequelae
Greinacher et al. Thrombosis Research. Thrombosis Research. 2005 In Press. Warkentin. J Crit Ill. J Crit Ill. 2005 ;20(1):6-13.
Slide 57
Summary of HIT Summary of HIT Diagnosis of HIT is based upon clinical suspicionDiagnosis of HIT is based upon clinical suspicion
Treatment of HIT should not be delayed while Treatment of HIT should not be delayed while awaiting laboratory confirmationawaiting laboratory confirmation
Untreated patients with HIT are at a high risk Untreated patients with HIT are at a high risk of having thromboembolic complicationsof having thromboembolic complications
Management of HITManagement of HIT– Discontinue all types of heparinDiscontinue all types of heparin
– Assess risk of thrombosisAssess risk of thrombosis
– Initiate alternative anticoagulant therapy, as indicatedInitiate alternative anticoagulant therapy, as indicated
Greinacher et al. Thrombosis Research. Thrombosis Research. 2005 In Press. Warkentin. J Crit Ill. J Crit Ill. 2005;20(1):6-13.