Andersons pediatric cardiology 1905

RiskFactorsforLateMortality
Identificationofriskfactorsforlong-termoutcomeandthedevelopmentof
modelsforriskstratificationhavethepotentialtotargettreatmentstothehighest
riskpatientsandtoguidethedevelopmentofnewtreatmentstrategies.Todate,
riskstratificationhasbeenhamperedbyarelativelysmallnumberofpatients
andbyinstitutionaldifferencesinpatientselectionandtreatmentregimens.
However,withtheincreasingnumbersofpatientsandthetrendtoward
multiinstitutionalnetworksandregistries,itislikelythatriskstratificationwill
becomeanessentialtooltoguidethedevelopmentofeffectivesurveillance
regimensandtargetedinterventions.

PreoperativeFactors
Preoperativeriskfactorsforlatedeathincludemalegender13,15andthe
diagnosisofhypoplasticleftheartsyndrome.12,16Ahigherpre-Fontanmean
pulmonaryarterialpressureisanimportantpredictorofmorbidityandmortality
inboththeearlyperioperativeandlatestages,withathresholdof15to17mm
Hgorlessbeingassociatedwithabetteroutcome.14,15,17Ahigherpulmonary
arterypressureisalsoassociatedwithprolongedpleuraleffusionsintheearly
postoperativeperiod,18aswellasthedevelopmentofPLEinthelatestage,14
bothofwhichindependentlypredictlatemortality.Havingacommon
atrioventricularvalve(CAVV)isalsoapredictoroflatedeath,19withalmost
50%ofCAVVshavingfailed20yearsafterFontansurgery.20Moreover,a
CAVVisfrequentlyassociatedwithheterotaxysyndromeandanomaliesof
pulmonaryandsystemicvenousdrainage,bothofwhicharealsoriskfactorsfor
latefailure(Table73.1).
Table73.1
RiskFactorsforLateMortality
Preexisting(preFontan)factors

Perioperativefactors

Earlypostoperative

Malegender
Hypoplasticleftheartsyndrome
Commonatrioventricularvalve
Highermeanpulmonaryarterypressure(>16–18mmHg)
TypeofFontan(atriopulmonaryworse)
OlderageatFontanoperation(>7years)
Operativecomplexity(e.g.,aorticcrossclamptime,bypasstime,concomitant
atrioventricularvalvereplacement)
ElevatedFontancirculationpressure(>20mmHg)


factors
Latepostoperative
factors

Elevatedventricularfillingpressure(>13mmHg)
Prolongedpleuraldrainage(>3weeks)
Protein-losingenteropathy
Tachyarrhythmia
Ventricularpacing
Reducedexercisecapacity(peakVO2)

PerioperativeFactors
ThosewithanatriopulmonaryFontanareatgreaterriskoflatedeathwhen
comparedwiththemorerecentvariations(Video73.1).13,21However,asurvival
advantageoftheextracardiacconduitoverthelateraltunnelhasnotbeen
demonstrated.7,22WhenFontanandcolleaguesreviewed160Fontansurgeries
from1968to1988,theyfoundolderageatFontansurgerywaspredictiveoflate

death.23Amorerecentexperiencesimilarlydemonstratedapoorerlatesurvival
whentheFontanoperationwasundertakenafter7yearsofage.13Surrogate
markersforsurgicalcomplexityincludinglongeraorticcross-clamptime,24
bypasstime,25andconcurrentatrioventricularvalvereplacement14alsoimpact
onlatesurvival.
Themainfactorsinthepostoperativecoursethatinfluencelatemortality
relatetothepresenceofelevatedpulmonaryarterialorFontanpathwaypressure.
Apostoperativeleftatrialpressuregreaterthan13mmHgorFontanpressure
greaterthan20mmHgisassociatedwithatwofoldincreaseinriskoflate
death.14Prolongedpleuraleffusions,usuallydescribedaschesttubedrainagefor
morethan3weeksaftersurgery,isoneofthestrongestpredictorsoflate
death.12–14Besidesbeingamarkerforelevatedpulmonaryarterialpressures,it
mayalsobeinfluencedbyotherfactors,includinglongercardiopulmonary
bypasstime,26thepresenceofaortopulmonarycollateralvessels,27andthe
absenceofafenestration.28,29


LatePredictors
Beyondtheperioperativeperiod,theidentificationofriskfactorsbecomesmore
challengingduetotheinsidiousnatureofdiseaseprogression.Thedevelopment
oflatecomplications,includingPLEandarrhythmia,andtherequirementfor
ventricularpacingaremarkersforlatefailureandaredescribedindetaillaterin
thischapter.
Cardiopulmonaryexercisestresstestingisanimportantprognostictoolinthe
Fontanpopulation.Ofallthemeasuredexercisevariables,peakVO2isthemost
robustinpredictinglatemorbidityandmortality.30,31ThosewithapeakVO2of
lessthan16.6mL/kg/minhaveamortalityriskseventimesofthosewitha
higherpeakVO2(Fig.73.6).32Alowerpeakheartrate33orreducedheartrate
reserve,21definedasthedifferencebetweenpeakexerciseandrestingheart
rates,hasalsobeenidentifiedasausefulmarkeroffunctionandprognosis.

However,itisimportanttorecognizethatconfoundingfactorssuchas
antiarrhythmictherapyandpacemaker-dependencemayinfluenceexercise
capacityandreduceitsprognosticpower.

FIG.73.6 SurvivalcurveforFontanpatientswithpeakVO2ofgreateror