James Zehnder, MDProfessor of Pathology and Medicine (Hematology)

Stanford University, Stanford, CA

May 6, 2017International Symposium on Technical Innovations in Laboratory Hematology

Honolulu, HI

Anti-Xa and APTT for UFH Monitoring

Casepresentation:57yearoldmanwithend-stageliverdisease

� Hospitalizedforlivertransplantevaluation� Hxportalhypertension,esophagealvarices,nobleeding.

� BaselinePT20sec(nl11-13sec),INR2.1,aPTT46sec(nl21-34sec)Totalbilirubin4.6

� Whileinhospital,patientdevelopedLLEfemoralveinDVT

• Thepatient’sINRof2.1atbaselineindicatesthatheisauto-anticoagulated– A:True– B:False

Patterns of Prohemostatic and Antihemostatic Drivers in the Different Phases of Hemostasis in Patients with Chronic Liver Disease.

Tripodi A, Mannucci PM. N Engl J Med 2011;365:147-156

Summary• Conventional wisdom is that chronic liver disease is an acquired

bleeding disorder.• However, the imbalance between procoagulant and

anticoagulant activities can also lead to thrombosis.• Studies are needed to assess the value of anticoagulants.

TripodiA,MannucciPM,NEJM2011

Casepresentation:57yearoldmanwithend-stageliverdiseaseandDVT- questions

◦ Thecliniciansdecidethattheriskofthrombosisextension/PEisgreaterthantheriskofbleedingfromanticoagulation.Theyaskforyouradvicegivenissueswithmonitoring.Whatwouldyourecommend?◦ A:Heparin◦ B:Argatroban◦ C:DOAC◦ D:LMWH◦ E:Warfarin◦ F:I’mgoingwiththefilterinthisone

Casepresentation:57yearoldmanwithend-stageliverdisease:Problemswithheparinmonitoring

• PatientstartedonUFHusingnomogramtargetingananti-Xaactivityrangeof0.3-0.7anti-Xa U/ml,andalsocheckingPTTforthefirst3determinations

• 24hourslater,anti-Xais0.7,butaPTTis>300sec• Thecliniciansareangryandsaythelabisgivingtheminaccurate

results• Whatdoyoudonow?

– A:Apologizeforthelaboratoryerror– B:Suggeststopmeasuringanti-Xa anddecreaseheparinuntilPTTin

therapeuticrange– C:Targetanti-Xa to0.3(lowerendofrangeratherthanupper)and

continuetomonitorPTT– D:ChangetoLMWHandstopmonitoring– E:ChangetoaDOACandstopmonitoring– F:Stopanticoagulationandputinafilter

Mastcells:sourceofheparin,limitdknowledgere:biologicalfunction

ZehnderJL,GalliSJ:Nature 400,1999

Heparinproductionfrompigintestines

Photo:NewYorkTimes,April2008

Wound

Tissue FactorVIIa

Xa

Thrombin

Fibrin

XIa

Control of theClotting Cascade

IXa

Every component of the clotting cascade is regulated by its physiologic inhibitor

TFPI/Xa

AT/heparin

PC/PS/TM

Va

VIIIa

Abriefhistoryofclinicaluseofheparin

• Priortoheparinuse:– Standardtreatmentofphlebitiswasbedrestandobservation

– Inoneseriesof29patientswithLEDVT• 24/29spreadtofemoralvein• 10/29developedcontralateralDVT• 11/29hadPE,2fatal.

Bauer G. The introduction of heparin therapy in cases of early thrombosis. Circulation 1959;19:108-109.

Firstrandomizedcontrolledtrialofheparintherapy:BarrittandJordan,1960

• VTEdiagnosedonclinicalgrounds• Patientsrandomizedtoobservationortherapywithheparin

andnicoumalonefor2weeks– Heparin10,000UIVq6h,nomonitoring– NicoumalonedosedtoPT2-3Xcontrol

• Interimanalysisoffirst35patients:– Observationarm:5/16diedfromPE– Treatmentarm:0/16died– 38subsequentpatientsenrolledintreatmentarm,nofatalPE

• StronglyinfluencedclinicalpracticeinfavorofRxVTE

Barritt DW, Jordan SC. Anticoagulant drugs in the treatment of pulmonary embolism. A controlled trial. Lancet 1960;1:1309-1312

Shouldheparinbemonitored?

InitialtrialsdosedonaweightbasiswithoutmonitoringConsideringrecenthx ofintroductionofLMWHs,DOACs- ifheparinwasbeingintroducedasanewanticoagulantin2017,wouldtherebeamonitoringrequirement?

HeparinMonitoring• 1972:PTT1.5-2.5baselineassociatedwithdecreasedriskrecurrentVTE

• Correlatedwithrangeof0.2-0.4U/mLbyprotaminetitrationor0.35-0.67U/mLanti-Xa activity

• EffectofheparinonPTTwidelyvariableamongdifferentreagent/instrumentsystems

• BasisofCAPrequirementtocalibrateaPTTtherapeuticrangetoprotaminetitrationof0.2-0.4U/mLoranti-Xaactivityof0.3-0.7U/mL

Basu D, Gallus A, Hirsh J, et al. A prospective study of the value of monitoring heparin treatment with the activated partial thromboplastin time. N Engl J Med 1972; Chiu HM, Hirsh J, Yung WL, et al. Relationship between the anticoagulant and antithrombotic effects of heparin in experimental venous thrombosis. Blood 1977; Levine MN, Hirsh J, Gent M, et al. A randomized trial comparing activated thromboplastin time with heparin assay in patients with acute venous thromboembolism requiring large daily doses of heparin. Arch Intern Med 1994

Clotting Pathways: Intrinsic, Common (measured by PTT)

Negativelychargedsurface

XIa

IXa

Xa

II IIa

Fibrinogen Fibrin

VIIIaa

Va

FactorXII

PartialThromboplastinTime(PTT):•Measuresclottingtimeaftercontactfactorsactivated.

•Usedtomonitorheparinanticoagulanttherapy

•InVitroassessmentofintegrityofintrinsicandcommonpathways

PTTissues• Appealingasafunctional“physiologic”readout ofthe

degreeofanticoagulation• However,interpretationofPTTiscontext-dependent:

– PTT of70seccouldbedueto:• Therapeuticlevelsofheparin• FactorVIIIdeficiencywithbleedingrisk• LAwiththrombosisrisk• FactorXIIdeficiencywithnobleedingorthrombosisrisk

• PTTreagentswidelyvariableintheirsensitivitytoheparinandotherbiologicalinterferences

• NoINRequivalenttoharmonizedifferentreagent/instrumentsystems

Shannon M. Bates, and Jeffrey I. Weitz Circulation. 2005;112:e53-e60

Copyright © American Heart Association, Inc. All rights reserved.

Idealtestcharacteristicsforanticoagulantmonitoring– PTTandanti-Xa

• Theassayresultshouldhaveawell-definedandpreferablylinearrelationshipwithclinicaloutcome(recurrentthrombosisandbleeding)

• Assayshouldhavegoodprecisionandbewell-standardizedamonglaboratoriesandassayreagents– partialcredit

• Theassayshouldbereadilyavailableandinexpensive- yesPTT

Eikelboom andHirsch,Thromb Haemost 2006

Backtothequestion:Shouldheparinbemonitored?

EvidencesupportingmonitoringisweakNationalPatientSafetygoalsmandateastandardmethodofmonitoringheparinWearestuckwithit.Stanfordprotocol(EMRheparinordersets):

CheckbaselinePT,PTT,plateletsPTTandanti-Xa testedfirst3determinationsFurthermanagementperanti-Xa-basednomogramsinEpicEMRAllpatientandlabdataisavailableforstudyinaclinicaldatarepository

PTT vs anti –Xa results

Decreased sensitivity of aPTTto heparin—heparin resistance

high VIII/Fibrinogen

Interference with APTT assessment of heparin effect

pregnancyrenal disease

inflammation

acquiredfactor deficiency

Increased sensitivity of aPTTto heparin

LupusAnticoagulant

congenitalfactor

deficiency(includes

mild FXII def.)

liver disease

warfarin

DICNone of these interfere with determination of heparin activity by anti-Xa assay

a47Yfemalewithh/oMarfan syndromeanda5.3cmaorticrootaneurysms/prepairHematologyconsultedforetiologyofhighPTTaftersurgery.Patientwasnotonanyanticoagulant.

Caseexample:elevatedaPTTaftersurgery

STAGO(Stagoreagents) ACLTOP(ILreagents)

DrawtimeaPTT

(nL:23.8-35.7s)

anti-Xa(UFH)

INR(nl:0.9-1.2)

CRPaPTT-ss

(nl:23.3-37.2s)

aPTT-sp(nl:23.3-37.2

s)

anti-Xa(UFH)(nl:<0.04U/dl)

SCT DRVVT

11/23/2016 26.0 1.0

12/8/2016 90.5 1.2 29.9 50.1 0.00 Neg Neg

Cardiovascularsurgeryon12/5/2016*

8.4

Baseline

AfterSurgery

Note:StagoaPTTreagent:aPTTautomated5;Instrumentationlaboratory(IL)reagent:aPTT-ss:aPTTSynthASil,aPTT-sp:lupussensitiveaPTTreagent

DidmarkedlyelevatedCRPprolongPTT?

C-reactiveproteinandphosphocholine binding

Crystal structure of C-reactive protein complexed with phosphocholine from Thompson et al.

Steven Black et al. J. Biol. Chem. 2004;279:48487-48490

©2004 by American Society for Biochemistry and Molecular Biology

Falseprolongationoftheactivatedpartialthromboplastintime(aPTT)ininflammatorypatients:interferenceofC-reactiveprotein

BritishJournalofHaematologyVolume157,Issue3,pages394-395,9JAN2012DOI:10.1111/j.1365-2141.2011.08990.xhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2011.08990.x/full#f1

STAGO(STAGOreagent) ACLTOP(ILreagents)

DrawtimeaPTT

(nL:23.8-35.7s)

anti-Xa(UFH)

(nl:<0.04U/dl)

INR(nl:0.9-1.2)

CRP(nl:<0.9mg/dl)

aPTT-ss(nl:23.2-36.0s)

aPTT-sp(nl:23.3-37.2s)

anti-Xa

(UFH)(nl:<0.04U/dl)

ATIII(nl:83-128%)

TT(nl:11.8- 14.4s)

SCT dRVVT FXII FXI FIX FVIII FX FVII

VWACT(nl:44-165%)

9/21/161307 33.0 <0.10 1.1

9/22/160239 50.2 0.16

9/24/160705 97.2 0.42

9/27/162111 53.3 0.18

9/28/161125 72.9 0.27 1.0

9/29/2016 9/29/16underwentCABG,MVrepair,Procedurewentuneventfully.Discordance notedaftersurgery. coagulationworkupstarted:

9/30/161617 84.3 <0.10 17.1 29.9 41.7 0.00 13.6 128 227 75

9/30/161703 16.3 30.0 49.6 0.07 16.9 128 207 68

10/1/160330 120.8 <0.10 1.3 21.5 30.9 54.4 0.02 15.6 Neg Neg

10/1/160945 116.5 <0.10 19.6 31.3 53.0 0.02 15.1

10/1/161959 37.7 73.1 0.10 78 20.8 104 164 248 317

10/2/160010 146.4 <0.10 21.4 38.1 86.3 0.09 21.2 65.8

10/2/160351 1.3 45.0 90.9 0.13 27.6

10/4/161835 107.9 <0.1 1.5 32.0 0.03 14.0 62

AnotherpatientwithelevatedaPTT aftersurgery

Therapeuticrangefrom0.3- 0.7anti-Xa U/mLcorrespondstoaPTTof78– 121secondsintheStanfordcoagulationlaboratoryusingaStagoSTA-RautomatedinstrumentandPTT-automatereagent.

aPTTandanti-XA(UFH)correlateswellbeforesurgery

A69Yfemales/pmitralvalvereplacementwith1vCABG,whoisbeingevaluatedbyHematologyconsultteamforetiologyofhighPTT.

Concordance of aPTT vs anti-Xa

Initialstudy:500patientswithpairedPTT/anti- Xa data

Patient Characteristic

Only PTT > anti-XaN=85

Only PTT= anti-XaN=112

StatisticP Value

Median age (y) 63 63 NSNumber male (%) 53 (62) 61 (54) NSNumber (%) on warfarin

47 (55) 23 (21) <0.001

Number (%) with elevated baseline PT prior to starting UFH

67/80 (84) 48/98 (49) <0.001

Number (%) with elevated baseline PTT prior to starting UFH

53/77 (69) 9/93 (10) <0.001

Number (%) dead within 30 days of first data pair

18(21) 4 (4) <0.001

PriceEA1,JinJ,NguyenHM,KrishnanG,BowenR,ZehnderJL.DiscordantaPTT andanti-Xa valuesandoutcomesinhospitalizedpatientstreatedwithintravenousunfractionatedheparin.AnnPharmacother. 2013Feb;47(2):151-8

Leverage extensive in-patient data from StanfordElectronic Health Record (EHR) and the StanfordCenter for Clinical Informatics databases (STRIDE)toward precisely characterizing the clinical andlaboratory factors associated with adverseoutcomes in this population.

Followup study 2009-2016, 7700 patients

Follow-up study 2009-2016Patient Demographic Overview

Gender n, (%)

Male 4,522 (58.9)

Female 3,224 (41.1)

Race

Asian 804 (10.1)

Black 416 (7.2)

White 4,876 (60.5)

Other 1,650 (22.2)

Ethnicity

Non-Hispanic 6,472 (82.5)

Hispanic 928 (13.4)

Unknown 346 (4.1)

Death

Recorded 2,159 (27.9)

Within 30 days of testing

865 (11.1)

Within 3 days of testing

360 (4.6)

Total 7746

DISTRIBUTION AND MORTALITY BY PAIRED aPTT/Anti-XA TEST RELATIONSHIP

High aPTT2,175

(461, 21%)

High Both1681

(229,14%)

High anti-Xa

1125 (108, 9%)

Normal38,647

(3567, 9%)

Paired Tests Per Quadrant, (mortality, n, % within 30 days)

DISTRIBUTION AND MORTALITY BY PATIENT

High aPTT1023

(202, 19.7%)

High Both1135

(157,14%)

High anti-Xa

739 (71, 9.6%)

Normal7434

(800, 10.8%)

# of Patients Per Quadrant, (mortality, n, % within 30 days)

Increased30dmortalityriskwithPTT>anti-Xa

Category Mortality p-value

Normal 800/7434(10.8)

ElevatedPTT

202/1023(19.7)

9.46x10-13*

ElevatedAnti-Xa

71/739(9.6)

0.416

ElevatedBoth

157/1135(13.8)

0.008

CONCLUSIONSOur studies demonstrate the extent of discordance in aPTTand anti-Xa values among hospitalized patients in atertiary/quarternary level care setting on anticoagulation.

In this setting, patients with elevated aPTT and therapeuticrange anti-Xa levels have a significantly higher rate ofmortality.

This elevated mortality is significantly higher than patientswith both elevated aPTT and anti-Xa, suggesting potentiallyserious underlying disease and therefore, opportunity forrevaluation of the indication for anticoagulation andanticoagulation goals.

FUTURE WORK

Sub-group analyses on high aPTT patients exploringadditional mortality factors.

Value-based assessment of relative-utility of the two tests inspecific subgroup of patients.

Casepresentation:57yearoldmanwithend-stageliverdisease:problemswithheparintherapy

• PatientstartedonUFHusingnomogramtargetingananti-Xaactivityrangeof0.3-0.7anti-XaU/ml

• 24hourslater,anti-Xais0.7,butaPTTis>300sec• Thecliniciansareangryandsaythelabisgivingtheminaccurate

results• Whatdoyoudonow?

– A:Apologizeforthelaboratoryerror– B:Suggeststopmeasuringanti-Xa anddecreaseheparinuntilPTTin

therapeuticrange– C:Targetanti-Xa to0.3(lowerendofrangeratherthanupper)and

continuetomonitorPTT– D:ChangetoLMWHandstopmonitoring– E:ChangetoaDOACandstopmonitoring– F:Stopanticoagulationandputinafilter

Casepresentation:57yearoldmanwithend-stageliverdisease:outcome

• UFHinfusionwasdecreasedtotargetof0.3anti-Xa U/mL– 6hourslater,anti-Xa 0.32,aPTT 120sec– Felttorepresentabalancebetweenadeqauteanticoagulationandbleedingrisk

– Patientdidwell,transitionedtowarfarin

Summary:PTTvs.anti-Xa forUFHmonitoring

• PTTandXavaluesarefrequentlydiscordantininpatientsonUFH• BaselineprolongationofPToraPTTisafrequentcauseofPTT>Xa

onUFH• Inflammatorystatescanincrease(CRP)ordecrease(Fn)sensitivity

toaPTT• DifferentaPTT reagent/instrumentsystemshavewidelyvariable

sensitivitytoheparin;usingratioof1.5-2.5tendstounderdose• Neithertestisideal;thebasisformonitoringingeneralisweak• Intertiary/quarternary levelhospitalswherecomorbiditiesaffecting

aPTT sensitivitytohepariniscommon,usefultohaveanti-Xa option• MeasuringbothPTTandXamayhaveutilityinselectedpatients• BetterstandardizationofaPTT reagentswithrespecttoheparin

effectandknowninterferenceswouldbeideal

Acknowledgements

SaurabhGombar MD,PhDAnandi KrishnanPhDJingJinMD,CLSDepartmentofPathology,StanfordUniversityClinicalLaboratories,StanfordHealthCare

stanford_edu.htm

Thereagentdiffisrightthere!

CRPPatient Drawtime aPTT anti-Xa(UFH) PT/INR TT Rept aPTT aPTT-sp HAL ATIII INR TT FXII FXI FVIII FIX FV FX FVII VWACTPatient4 11/3/20162122 113.4 27.9/2.8 55.3 43.3/3.69

11/4/160743 77.1 16.9/1.5 <13.0 9.5 39.7 48.7 0.00 14.3/1.28 13.0

10/25/161244 71.2 0.23 1.510/27/161636 116.6 2.710/29/160610 62.2 <0.10 1.510/29/161610 74.2 12.7 31.1 56.5 0.05 1.27 15.110/29/161723 12.3 29.4 47.2 0.00 1.24 13.9 Drvvt;Screen:36.6[nl:29-46sec]Confirm:34.0Normalizedratio:0.9510/30/160544 73.7 1.3 15.2 34.3 61.1 0.04 71 1.26 14.9

9/21/161307 33.0 <0.10 1.19/22/160239 50.2 0.169/24/160705 97.2 0.429/27/162111 53.3 0.189/28/161125 72.9 0.27 1.09/30/161617 84.3 <0.10 17.1 29.9 41.7 0.00 13.6 227 128 759/30/161703 16.3 30.0 49.6 0.07 16.9 207 128 68.410/1/160330 120.8 <0.10 15.9/1.3 21.5 30.9 54.4 0.02 15.610/1/160945 116.5 <0.10 19.6 31.3 53.0 0.02 15.1

10/1/161635 108.2 <0.10 dRVVTneg10/1/161959 37.7 73.1 0.10 78 20.8 104 248 164 31710/2/160010 146.4 <0.10 21.4 38.1 86.3 0.09 21.2 65.810/2/160351 15.9/1.3 45.0 90.9 0.13 27.610/4/161835 107.9 <0.1 17.1/1.5 32.0 0.03 14.0 6210/7/161419 4.211/3/20160416 >300.0 0.44 21.5/2.0 131.7 0.489/22/162016 29.3 1.1

9/25/161749 60.39/25/161813 27.79/26/171147 <13.0 12.99/26/161536 60.29/26/161750 26.8 28.7 50.3 0.00 86 14.0 73 68 179.2 1449/27/160317 79.6 <0.10 14.2/1.2 15.9 31.5 79.8 0.02 15.610/1/161556 81.6 <0.10 13.8/1.1 32.9 49.8 0.03 19.910/2/150515 45.6 26.9 41.4 0.00 16.510/2/160935 27.3 46.3 0.00 15.2 101 69

4/24/20171259 1.14/25/20172017 173.5 0.24 8.84/25/20172122 176.3 0.23 55.9 >400.0 0.27 92.5 DRVVTneg4/25/20172358 51.8 <0.10 29.5 43.4 0.00 15.94/26/20170353 90.4 <0.10 1.3 29.5 42.2 0.00 68 16.3

Patient5

Patient1

NegativeratiosfromLACpairedtestsSCTandDRVVT(couldneutrlaizeHepupto1.0u/ml)indicatingLACnegative.

STAGO ACLTOP(ILreagents)

Patient3

Patient2

PT:26.6/2.31

9/29/16underwentCABG,MVrepair,Procedurewentuneventfully.Discordanthappenedrightaftersurgery

UFH:300Units/hr:3mL/hrsince10/29/16

9/23/16:WenttoORforMVRandAVR.Receivedheparin25000unit(s)IVprndose.at9:30amthen5000unit(s)prndoseat9:30am.Wasonxareltobeforesurgery.

Dischargedafter10/10/16withtherapeuticalwarfarin.Thengotre-admittedon10/28/16forsubtherapeuticINR.Heparinwasstartedtobridgewarfarin

Aorticvalvestenosiss/pAVRon4/24

Casepresentation:57yearoldmanwithend-stageliverdisease:problemswithheparintherapy

• PatientstartedonUFHusingnomogramtargetingananti-Xaactivityrangeof0.3-0.7anti-XaU/ml

• 24hourslater,anti-Xais0.7,butaPTTis>300sec• WhyaretheaPTTandanti-Xadiscordant?

– A:BecausebaselinePTandPTTprolonged– B:Anti-Xaisnotvalidinliverdisease– C:Laboratoryerror– D:Testinterferenceduetoincreasedbilibrubin

SyntheticPentasaccharide

*P=0.0316comparedtoOnlyaPTT=anti-Xa group#P=0.0202comparedtoOnlyaPTT=anti-Xa group§P=0.0008comparedtoOnlyaPTT=anti-Xa group

Outcome Two Consecutive aPTT>anti-Xa

(n=163)

Only aPTT=anti-Xa(n=112)

Only aPTT>anti-Xa(n=85)

Number (%) with major bleeding within 21 days following first data pair

15 (9)* 3(3) 5(6)

Number (%) with new thrombotic event within 21 days following first data pair

9 (6) 2 (2) 3 (4)

Number (%) dead within 30 days following first data pair

23 (14) # 6 (5) 18 (21) §

Majorbleeding,thrombosisanddeathinthethreepatientgroups

Idealtestcharacteristicsforanticoagulantmonitoring

• Theassayresultshouldhaveawell-definedandpreferablylinearrelationshipwithclinicaloutcome(recurrentthrombosisandbleeding)

• Assayshouldhavegoodprecisionandbewell-standardizedamonglaboratoriesandassayreagents.

• Theassayshouldbereadilyavailableandinexpensive.

Eikelboom andHirsch,Thromb Haemost 2006

AssociationofaPTT withclinicaloutcomes:Thrombosis

• RxofacuteVTE– AchievingtherapeuticaPTTwithin24hassociatedwithdecreasedrisk– Howeversubsequentmeta-analysesofVTERxtrials:Ifheparingivenasinitialbolusthenatleast30,000U/24hnosignificantassociationofoutcomewiththerapeuticaPTT infirst24h.

HullRD,Raskob GE,Rosenbloom D,etal.ArchInternMed1992;Anand S,GinsbergJS,Kearon C,etal.ArchInternMed1996; Anand SS,BatesS,GinsbergJS,etal.ArchInternMed1992.

AssociationofaPTT withclinicaloutcomes:Bleeding

• Increaseinmajorbleedingseeninsomebutnotallstudies:– Hulletal(ArchInt Med1992):Noassociationwithsupratherapeutic aPTT andmajorbleeding

– Anand etal(ArchInt Med1992):SubgroupanalysisofOASIS-II– 7%increaseinbleedingrisk/10secaPTTprolongation

• Patientriskfactors:age,comorbidity,recentsurgery

ComparedtotheOnlyaPTT=anti-XaPatientGroup(6outof112,5%),30-daymortalitywassignificantlyhigherintheOnlyaPTT >anti-Xapatientgroup18of85(21%)(p<0.001).Nineof17(53%)ofthedeceasedpatientsinOnlyaPTT >anti-XapatientgrouphadelevationsinbothPTandaPTT atbaseline.(Excludedonedeceasedpatientwhodidn’thavebaselinePTandaPTT.)

9of1753%

5of1729%

2of1712%

1of176%

0

1

2

3

4

5

6

7

8

9

10

BaselinePT,aPTTelevated

BaselinePTelevated,aPTTnormal

BaselineaPTTelevated,PTnormal

BaselinePT,aPTTwithin normallimits

BaselinePT,aPTT Status