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MillsPeninsulaHospitalCardiovascularCo-managementMetric
NewOnsetPostoperativeAtrialFibrillationPreventionProtocolfor
CardiacSurgeryPatients
Background:
Newonsetpostoperativeatrialfibrillation(POAF)affectsapproximately11-40%ofpostcardiacsurgery
patients.Itisthesinglemostcommonpostoperative“complication”observed.Numerousstudies
havelinkedPOAFtoincreasedperioperativemortality,lengthofstay,hospitalreadmission,aswellas
hospitalcost.
Adiverseregimenofprophylacticstrategieshavebeentrialed,withvaryingdegreesofsuccess.
Bothbetablockersandamiodaronehavebeenidentifiedtobeeffectiveandrelativelysafechoices,and
havebeenshowntodecreasetheincidenceofPOAFbyupto50%.Additionally,theventricularratein
thosepatientswhodoexperiencePOAFwerebettercontrolled.
ThecurrentprotocolwillfocusontheprophylaxisandpreventionofnewonsetPOAF,andnotonthe
treatmentofPOAF.
Objective:
ToimplementaneffectiveprotocoltodecreasetheincidenceofPOAFincardiacsurgerypatientsand
positivelyimpactperioperativeoutcomes.
Thisprotocolisnotmeanttobeaclinicaltrial,norisitmandatory.Thesurgical/medicalteamwill
alwayshavethediscretiontoimplementand/orwithdrawfromtheprotocolbasedontheclinical
situation.
Method:
Therearethreeenvironmentswherethereisanopportunitytoinitiatetheprotocol.Those
environmentsarethepreoperative,intraoperative,andimmediatepostoperativephasesgenerally
correspondingtooutpatient,operatingroom,andinpatientsettings.
ThecausesofPOAFarelikelymulti-factorial.Avarietyofpatientfactorsaswellassurgicaltechnical
factorshavebeenimplicated.
FactorsImplicatedinPostoperativeAtrialArrhythmias
Atrialtrauma/inflammation
Atrialstretch
Atrialischemia
Epicardial/Pericardialinflammation
Hypoxia
Acidosis
Electrolyteimbalances
Sympatheticautonomousdischarge
Circulatingcatecholamines
TargetPopulationandInclusionCriteria:
AllpatientsundergoingcardiacsurgeryatMillsPeninsulahospitalarepotentialcandidatesforthe
protocol.Eachpatientmustbeapproachedindividuallyandverballyconsenttotheprotocol.A
handoutwithgeneralinformationwillbemadeavailabletofacilitateenrollment.
Patientswithpre-existingatrialfibrillation(paroxysmalorpersistent)orotheratrialtachycardiasare
alsoeligibleforthisprotocol,howeverwillnotbeincludedintheoutcomesassessment.Athorough
historyofpre-existingatrialfibrillationorotheratrialtachycardiasshouldbedocumented.
WhilePOAFisobservedinpatientsundergoingalltypesofcardiacsurgerybothemergentandelective,a
highriskcohortcanbeidentified.
HighRiskPopulationforDevelopmentofPOAF
Elderly(age>70)
Valvularoperationsorcombinedvalve/CABG
Multiplepre-existingcomorbidities:(HTN,renalfailure,CVA,CHF)
Enlargedatrialchambers>6cm
HighcalculatedSTSPROMscore
Patientswiththesecharacteristicsshouldbeidentifiedashighriskandimplementingprophylactic
measuresshouldbeconsidered.
Exclusioncriteria
Patientswithpre-existingatrialarrhythmiasarenotexcludedbutwillnotbeincludedintheoutcomes
assessment.
Patientsalreadyreceivingeitherorbothprotocolmedicationsshouldcontinuethemuntilthetimeof
theoperation.
1. Exclusionguidelinesforstartingbetablockers
a. Bradycardia<50,
b. Pre-existing2ndor3rddegreeheartblock
c. PoorlycontrolledCHF(NYHAclassIIIorIV)orsevereLVdysfunctionprohibiting
usageofbetablocker
d. Historyofasthma/obstructivelungdisease,
e. Allergiestobetablockers
2. ExclusionguidelinesforstartingAmiodarone
a. Bradycardia<50,
b. Pre-existing2ndor3rddegreeheartblock,
c. ProlongedQTc>480msecifQRS<120msecorQtc>530msecifQRS>120msec
d. Untreated/unstablehypo/hyperthyroidism,
e. Interstitiallungdisease/pulmonaryfibrosis,
f. Allergiestoiodine/amiodarone
g. Womenofchild-bearingage/pregnancy
h. Livertransaminasestwicenormallimit
PatientstakingotherAVnodalblockingagents,otherantihypertensivemedicationsareatriskfor
developingheartblockorsymptomatichypotension.Aclinicaldecisionshouldbemadeaswhetheror
nottostartthesepatientsontheprotocol.
Althoughcoumadinwilltypicallybediscontinuedpriortosurgery,patientoncoumadinandamiodarone
shouldhavetheircoumadindosedecreasedby50%.
Pregnantorlactatingpatientsshouldnotreceiveamiodarone.
AtrialFibrillationProphylaxisProtocol
Themedical/surgicalteamwillidentifyapatientscheduledtoundergocardiacsurgeryandmakea
clinicaldecisionastowhethertheprotocolshouldbeimplemented.
Thepatientshouldbeinformedoftheprotocol,andconsentobtained.
1. Preoperativetesting
a. Reviewofhistorytoidentifyallergiesorpre-existingarrhythmias
b. PhysicalexaminationtoruleoutactiveCHF
c. BaselineEKG
d. Thyroidfunctionpanel
e. Bedsidespirometry
f. StandardbloodworkforsurgeryincludingcoagulationstudiesandLFTs
TimingandDosage
Anewprescriptionwillbegiventothepatientintheoutpatientsetting.
Amiodarone
1. Preoperative:Maystartanytimepriortosurgery,howeverideally5dayspriorto
operation.
a. Dosage:
i. Patientweight>70kg,400mgBID
ii. Patientweight<70kg,200mgBID
iii. IfunabletotakePOmedication,Amiodaronedrip(150mgIVbolusfollowed
bydrip)canbeadministered,alternativelyAmiodaroneviaanNGT/OGTcan
beconsidered
2. Intraoperative:
a. Ifthepatientdidnothavetheopportunitytoreceiveaproperpreoperativedose,
intraoperativeamiodarone150-300mgIVcanbegivenasabolusintheoperating
room.
b. Allpatientsontheprotocolshouldhavetemporaryventricularpacingwiresplaced
orothermeansofreliablepacing.
3. Postoperative:ifstablehemodynamics(cardiacoutputandrhythm)medicationsshould
continueuntilpostopday5
a. Dosage:
i. Patientweight>70kg,continueAmiodarone400mgbiduntilPOD#5
ii. Patientweight<70kg,continueAmiodarone200mgbiduntilPOD#5
iii. IfunabletotakePOmedication,Amiodaronedrip(150mgIVbolusfollowed
bydrip),alternativelyAmiodaroneviaanNGT/OGTcanbeconsidered
4. BeyondPOD#5andfollowingdischarge:ItisreasonabletocontinueAmiodaronebeyond
theinitial5postoperativedaysatthesurgeon’sdiscretion
5. Ifcontinuedpost-discharge,Amiodaronetherapyshouldbestoppedonemonthpostsurgery.
Betablockers
1. Preoperative:Maystartanytimepriortosurgery,howeverideally5dayspriorto
operation
a. Dosage:
i. Ifalreadyonbetablocker,continuedoseuntiltimeofsurgery
ii. Lopressor25mgbid(canreducedoseifborderlinebradycardicor
hypotensive)
iii. IfunabletotakePO,thenLopressor5mgIVq6hours
2. Intraoperative:norecommendations
3. Postoperative:ifthepatienthasstablehemodynamics(stablecardiacoutputandrhythm)
a. Dosage:
i. StartLopressor25mgPObid
ii. IfunabletotakePO,thenLopressor5mgIVq6hours
4. BeyondPOD#5:ItisreasonabletocontinueLopressorbeyondtheinitial5postoperative
daysatthesurgeon’sdiscretion.Alternatively,thepatient’soutpatientbetablockadecan
besubstituted.
5. Ifthepatienthasacardiomyopathy,convertLopressortoToprol-XLorCoregpriorto
discharge.
6. AvoidotherQTprolongingagentswhileonamiodarone.
Outcomes:
TheincidenceofnewonsetPOAFwillbetracked.ThedefinitionofPOAFwillbecongruentwithSTS
guidelines.
Potentialsideeffectsandcomplications
Theshortdurationoftherapyfortheprotocol(10days)waschosentominimizepotentialsideeffects
andcomplications.
Intheliterature,useofamiodaronewasassociatedwithanincreasedincidenceofbradycardia,
hypotension,andneedfortemporarypacing.Pulmonarytoxicityfromshorttermexposureto
amiodaroneseemstobeextremelyrarebuthasbeenreported.Theincidenceofpermanentpacemaker
implantationwasnotincreased.
Theincidenceofintraoperativecomplicationsandmajoradverseoutcomesfollowingsurgerydonot
appeartoincreasewiththisdosingregimen.
Thereisnopublishedconsensusfromtheprofessionalsurgicalsocietiesinregardstoimplementingsuch
aprotocol.(RecentguidelineswerepublishedbytheSTSforGeneralThoracicSurgery).Therefore,
acceptanceandimplementationofthisandsimilarprotocolsisatbest,sporadicacrossthecountry.
Withanyprophylactictreatment,avoidanceofmajoradverseoutcomesrelatedtotheregimenis
imperative,asthiswoulddefeattheentirepurposeofthestrategy.
Theclinicalteammustthereforeacceptthattherewillinevitablybeanincreaseincertainadverse
events(bradycardia,hypotension,needfortemporarypacing),howeverthebenefitsthatwillultimately
begainedbythepreventionofPOAFwilloutweighthesecomplications.Alongerhospitalstayis
anticipatedundercertaincircumstancestoavoidpacemakerplacementintheeventofbradycardia
thoughttoresultwiththeeliminationofAVNblockingagents.
References:
1.PostoperativeAtrialFibrillationSignificantlyIncreasesMortality,HospitalReadmission,andHospital
Costs.LaPar,DamienJ.etal.TheAnnalsofThoracicSurgery2014,Volume98,Issue2,527–533
2.RostagnoC,LaMeirM,GelsominoS,etal.Atrialfibrillationaftercardiacsurgery:incidence,risk
factors,andeconomicburden.JCardiothoracVascAnesth2010;24:952–8.
3.SaxenaA,DinhDT,SmithJA,ShardeyGC,ReidCM,NewcombAE.Usefulnessofpostoperativeatrial
fibrillationasanindependentpredictorforworseearlyandlateoutcomesafterisolatedcoronaryartery
bypassgrafting(multicenterAustralianstudyof19,497patients).AmJCardiol2012;109:219–25.
4.MathewJP,FontesML,TudorIC,etal.Amulticenterriskindexforatrialfibrillationaftercardiac
surgery.JAMA2004;291:1720–9.
5.ProphylacticAmiodaroneforPreventionofAtrialFibrillationAfterCardiacSurgery:AMetaAnalysisBagshaw,SeanM.etal.TheAnnalsofThoracicSurgery2006,Volume82,Issue5,1927–1937
6.PreoperativeAmiodaroneasProphylaxisagainstAtrialFibrillationafterHeartSurgeryDaoudEGetal.,
NEnglJMed1997;337:1785-1791