Andersons pediatric cardiology 1662
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regardingoverallarrhythmiariskisunknown,buttheremaybesomecorrelation
withworseningventricularfunctionaswellasthespecificgenetictrigger,such
asscn5aorlmnamutations.425Thetrueprevalenceislikelyunderestimatedin
LVNC,giventhelimitedapproachtoarrhythmiasurveillanceinclinicalpractice.
ThromboembolicDisease
ThromboembolismmaybeseeninLVNCandhasbeenreportedtooccurin10%
to25%ofadults;itmaypresentasacerebrovascularaccident,transientischemic
attack,mesentericinfarction,myocardialinfarction,orperipheral
embolism.425,426Thromboemboliceventshavebeenreportedinchildrenbut
likelyoccurlesscommonlyinthemthaninadults.410Thrombimayoriginate
fromtheventricularcavityinthesettingofdysfunctionanddilation,the
intertrabecularrecesses,ortheatria,especiallyinthosepatientswiththe
restrictiveformofLVNCand/oratrialfibrillation.
ClinicalFeatures
PhysicalExamination
ThediagnosisofLVNCcanbedelayed,givenlimitedawarenessofthedisease
andthelackofconsensusregardingdiagnosticcriteria.Indexcasesshould
undergoathoroughhistoryandphysicalexaminationwithcarefulattentionto
cardiacsymptoms,includinghistoryofunexplainedsyncope.Inaddition,a
three-generationpedigreeshouldbeobtained.Themajorityofpediatricpatients
withLVNCwillhavenoobviousabnormalitiesonphysicalexamination.
However,bothchildrenandadultswithLVNCmayhavephysicalexamfindings
consistentwiththephenotypicexpressionofdisease(examfeatureswithDCM,
RCM,etc.).
Anotableexceptiontothegeneralphysicalexamfindingsispatientswith
Barthsyndrome.Barthsyndromeischaracterizedbycardiomyopathy,skeletal
myopathy,neutropenia,growthfailure,distinctivefacialfeatures,developmental
delay,andaciduria.Unfortunatelythevariableseverityofphenotypicexpression
mayleadtodelayeddiagnosis.289,427–429
ElectricalAbnormalitiesandArrhythmias
ECGabnormalitiesareseeninthemajorityofpatientswithLVNC.411,412
Commonabnormalitiesincludeleftventricularhypertrophy,diffuseorisolated
T-waveinversion,ST-segmentabnormalitiesorstrainpattern,leftaxisdeviation,
prolongedQTcinterval,andpreexcitation.
Supraventriculararrhythmiashavebeenreportedandincludeatrial
fibrillation,atrialflutter,andparoxysmalsupraventriculartachycardia.Complete
atrioventricularblockhasalsobeenreported.Ventriculartachycardiahasbeen
reportedandmaypointtopatientsathigherriskofsuddencardiacdeath.
BradyarrhythmiashavealsobeenseeninpatientswithLVNC.
Echocardiography
Echocardiographyhasbeenthemainstayinmostcentersforthediagnosisand
follow-upofLVNC.Thereareseveralproposedechocardiographiccriteriafor
thediagnosisofisolatedLVNC,420,430themostcommonlyusedbeingthose
proposedbyJennietal.431Theseinclude(1)absenceofcoexistingcardiac
abnormalities,(2)segmentalthickeningoftheleftventricularmyocardialwall,
consistingofathincompactedepicardiallayerandathickenedendocardiallayer
withevidenceofdeeprecessesandprominenttrabeculations,(3)noncompaction
tocompactionratioofgreaterthan2atend-systole,(4)localizationofcardiac
pathologyintheapical,midlateral,andmidinferiorregionsoftheLV,and(5)
colorDopplerevidenceofdeepintertrabecularrecesses.
CardiacMagneticResonanceImaging
CMRIisincreasinglyusedinclinicalpracticetoeitherestablishorconfirmthe
diagnosisofLVNC.CMRIisalsohelpfulindelineatingcardiacmorphologyin
thosesubjectswithpooracousticwindows.Petersenandcolleaguesdeveloped
criteriafortheCMRIdiagnosisofLVNC.432Thatdiagnosisismadewhenthe
ratioofnoncompactiontocompactionis2.3:1indiastole.Quantitative
diagnosticcriteriahavealsobeendevelopedusingnoncompactedmassand
higherratiosofnoncompaction.433,434Overall,thedegreeoftrabeculationdoes
notappeartohaveasignificantprognosticimpactafteraccountingforother
phenotypiccharacteristics.409
Management
HeartFailure
SpecifictherapieshaveyettobedevelopedforthetreatmentofLVNC.
However,treatmentistypicallydirectedattheconcomitantphenotype,as
describedinothersectionsofthischapter.Forthosepatientswiththedilated
LVNCphenotype,conventionalheartfailuretherapiesaretypicallyemployed
basedonexistingguidelines.Werecentlyevaluatedtheefficacyofconventional
remodelingtherapiesinchildrenwithLVNCandfoundimprovementinejection
fractionandend-diastolicdimensions.435ForthosepatientswiththeHCM
LVNCphenotype,considerationofmedicaltherapymaybegiventothosewith
symptomaticobstruction.Mechanicalcirculatorysupportmaybeneededin
somepatients,basedonguidelinesandlocalpractice,andcardiactransplantation
maybeaconsideration,especiallyforthosewiththerestrictiveLVNC
phenotype.
Arrhythmias
Significantandpotentiallylife-threateningarrhythmiasoccurcommonlyin
LVNC.TheLVNCsubtypeassociatedwithearly-onsetarrhythmiashasariskof
suddendeath.
Thromboembolism
Thepreventionofthromboembolicdiseaseisanimportantpartofthe
managementstrategyinpatientswithLVNC.Thisisofparticularimportancein
patientswithsystolicdysfunction(LVEF<40%),atrialfibrillation,orahistory
ofthromboemboliccomplications.Somecentersusesystemicanticoagulation
forprimarypreventionofcomplications,butthereareonlylimiteddatato
supportthisapproach.Datainchildrenareverylimited,butmanycentersput
patientsonprophylacticaspirinforprimaryprevention,especiallyinthesetting
ofmyocardialdysfunction.Theseapproachesmustbeconsideredcarefullywhile
alsoassessingthepotentialriskandbenefitineachpatient.
