Andersons pediatric cardiology 1656
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guidelinesthatdoexistacknowledgethelackofhigh-qualitypediatric
studies.309MedicaltherapyisbasedonextrapolateddatafromadultDCM,and
whetherthisisapplicableremainsunclear.275,310
DiureticsandMineralocorticoidAntagonists
Loopdiureticsaretypicallytheinitialtherapyforsymptomatictreatment.
Thiazidediureticsmayalsobeusedasmonotherapyorinadditiontoloop
diuretics.Themineralocorticoidantagonistsspironolactoneandeplerenonehave
beenshowntoimproveoutcomesinadultswithsymptomaticheartfailureand
reducedejectionfraction(HFrEF).311,312Therearefewdataassessingtheeffect
ofmineralocorticoidantagonistsinchildrenoutsideofpatientswithmuscular
dystrophy.Earlystudieshavesuggestedthateplerenonemayhaveatherapeutic
benefitinpatientswithDuchennemusculardystrophy.313
Angiotensin-ConvertingEnzymeInhibitorsand
AngiotensinReceptorBlockers
Multiplelargemulticenter,placebo-controlledtrialshaveshownthat
angiotensin-convertingenzymeinhibitorsandangiotensinreceptorblockers
improvecardiovascularoutcomesinadultswithHFrEF.314–317Retrospective,
single-centerandmulticenterstudiesinchildrenhavereportedamoremixed
effect.274,275,318,319However,thesestudiesarelimitedbytheirretrospective
nature,inconsistentdosingstrategies,andpatientselectionbias.Earlyinitiation
ofangiotensin-convertingenzymeinhibitorsinpatientswithdystrophinopathy
maydelaytheonsetofcardiacdysfunctionandslowtheprogressionof
myocardialfibrosis.320,321
β-Blockers
Multiplelarge,multicenter,placebo-controlledtrialshaveshownthatβ-blockers
improveoutcomesinadultswithHFrEF.322,323Studiesexaminingtheeffectsof
β-blockersinchildrenarelimited.324,325Thelargeststudytodateshowedno
differenceinoutcomeamongchildrenwhoreceivedcarvedilol.326However,this
includedaheterogeneouspopulation(includingpatientswithcongenitalheart
diseaseandacrossarangeofages).Recentdatasuggestthatage-andgenotype-
dependentβ-adrenergicsignalingandpharmacokineticsmaydriveoutcomeand
therapeuticresponseandthusmayobscurethepotentialtreatment
effect.310,327–329
Anticoagulation
TheriskofthromboembolisminpediatricDCMisnotwelldefined.Studiesin
adultshavesuggestedthatwarfarindoesnotprovideatherapeuticbenefitamong
mostpatientsinsinusrhythm;however,improvedoutcomesmaybeseenin
patientswithgreatertimeinthetherapeuticrange.330,331
OtherTherapies
Digoxinimprovessymptomseveritybutnotoutcomeinadultswithheart
failure.332,333Routinemonitoringofdigoxinconcentrationisrecommended,
giventheassociationbetweenhigherdigoxin(>1to1.1ng/mL)levelsand
mortalityinadultswithheartfailure.334,335Datainpediatricpatientsareagain
limited.
CardiacResynchronizationTherapy
Cardiacresynchronizationtherapyreducessymptomsandimprovesleft
ventricularfunctioninsubgroupsofadultswithHFrEFandcardiac
dyssynchrony.336–338Cardiacresynchronizationtherapyappearstoconfersome
benefitsinpediatricpatientswithelectromechanicaldyssynchrony;however,the
studiestodatehavelargelyfocusedontheuseofshort-termcardiac
resynchronizationtherapyinpatientswithrepairedcongenitalheart
disease.339,340Itremainsunclearwhetherthelong-termuseofcardiac
resynchronizationtherapyisbeneficialinpediatricpatientswithDCMandthe
patientpopulation(includingQRSduration)thatmaybenefitmostfromtherapy.
TherapyWithVentricularAssistDevices
Ventricularassistdeviceshavebeenshowntoimproveoutcomesamongchildren
withend-stageheartfailureduetoDCM.341–343Theuseofventricularassist
devicesandhearttransplantationarediscussedindetailinotherchapters.
RestrictiveCardiomyopathy
Definition
RCMischaracterizedbynormalordecreasedventricularvolumes,normalleft
ventricularwallthickness,normalornear-normalsystolicfunction,anddiastolic
dysfunctionwithbiatrialenlargement.
Epidemiology
RCMistheleastcommonofthecardiomyopathiesandaccountsfor
approximately3%ofcardiomyopathycasesinchildren.267,268Thereisno
genderpredominanceinRCM.Themajorityofpatientspresentbetween1year
ofageandtheteenageyears.267–269
ClinicalOutcomes
Historicallytheoutcomeshavebeenquitepoor.Patientsareatriskofsudden
deathaswellasprogressiveheartfailure,withreportedactuarialsurvivalof
approximately50%at2yearsafterdiagnosis;insomepatientsthereisrapid,
fulminantdiseaseprogression.344–346However,theoutcomeswerenotuniformly
poor,with30%to50%ofpatientssurvivingformorethan5yearsfromthetime
ofdiagnosis.345,347,348Giventhattheoptimaltimingforlistingwasunclear,
earlylistingfortransplantationhasbeencommon.Thewaitlistoutcomesfrom
thePediatricHeartTransplantStudyreflectthecompetingrisks.349Thereisan
earlyhazardfordeath,especiallyinstatus1patientsandthosebelow1yearof
age,whereasolderpatientshaveabetterprognosis.Infact,40%ofthewaitlist
mortalityoccurredininfants,inspiteofthefactthattheyaccountedforonly
10%ofthelistedpatients.AnalysisofdatafromthePCMRshowedsimilar
results.Therewasanearlysignificantriskfordeath,asthemediantimefrom
diagnosistodeathwas0.3monthsinthepatientswhodidnotsurvive.350
Progressiveheartfailurewasthemostcommoncauseofdeath,followedby
suddendeath,whereasstrokewasrareandoccurredinonly1patient.
Symptomaticheartfailureandlowerfractionalshorteningwereassociated
adverseoutcomesinthiscohort.Theriskofsuddendeathwassignificantly
lowerinthedatafromtheNationalAustralianChildhoodCardiomyopathy
