Evidence from an autopsy study

16 Pages·2017·6.76 MB·English

RESEARCHARTICLE
Morphometric measurements of systemic
atherosclerosis and visceral fat: Evidence
from an autopsy study
AlineNishizawa1,2*,ClaudiaK.Suemoto1,2,3,DanielaS.Farias-Itao1,2,Fernanda
M.Campos1,KarenC.S.Silva1,2,MarcioS.Bittencourt4,5,LeaT.Grinberg2,6,7,RenataE.
P.Leite2,3,RenataE.L.Ferretti-Rebustini2,8,JoseM.Farfel2,3,WilsonJacob-Filho2,3,
CarlosA.Pasqualucci1,2,7
a1111111111 1 LaboratoryofCardiovascularPathology(LIM-22),DepartmentofPathology,UniversityofSaoPaulo
MedicalSchool,SaoPaulo,Brazil,2 PathophysiologyinAgingLab/BrazilianAgingBrainStudyGroup(LIM-
a1111111111
22),UniversityofSaoPauloMedicalSchool,SaoPaulo,Brazil,3 DisciplineofGeriatrics,UniversityofSao
a1111111111
PauloMedicalSchool,SaoPaulo,Brazil,4 DivisionofInternalMedicine,UniversityHospitalandStateofSão
a1111111111 PauloCancerInstitute(ICESP),UniversityofSãoPaulo,SaoPaulo,Brazil,5 PreventiveMedicineCenter,
a1111111111 HospitalIsraelitaAlbertEinsteinandSchoolofMedicine,FaculdadeIsraelitadeCiênciadaSau´deAlbert
Einstein,SãoPaulo,Brazil,6 DepartmentofNeurology,MemoryandAgingCenter,UniversityofCalifornia,
SanFrancisco,UnitedStatesofAmerica,7 DepartmentofPathology,UniversityofSaoPauloMedical
School,SaoPaulo,Brazil,8 DepartmentofMedicalSurgicalNursing,UniversityofSãoPauloNursing
School,SaoPaulo,Brazil
OPENACCESS *[email protected]
Citation:NishizawaA,SuemotoCK,Farias-ItaoDS,
CamposFM,SilvaKCS,BittencourtMS,etal.
(2017)Morphometricmeasurementsofsystemic Abstract
atherosclerosisandvisceralfat:Evidencefroman
autopsystudy.PLoSONE12(10):e0186630.
https://doi.org/10.1371/journal.pone.0186630
Background
Editor:QinghuaSun,TheOhioStateUniversity,
Morphometricmeasurementsofsystemicatherosclerosisanddirectquantificationofvis-
UNITEDSTATES
ceralfatareonlypossibleusingmaterialsfromautopsystudies.However,thefewautopsy
Received:July1,2017
studiesthathaveinvestigatedtheassociationofvisceralfatwithatherosclerosishadsmall
Accepted:October4,2017
samplesizesandfocusedoncoronaryarteriesofyoungormiddle-agedWhitesubjects.We
Published:October16,2017 aimedtoinvestigatetheassociationofpericardialfat(PF)andabdominalvisceralfat(AVF)
Copyright:©2017Nishizawaetal.Thisisanopen withatherosclerosisintheaorta,coronary,carotid,andcerebralarteriesinalargeautopsy
accessarticledistributedunderthetermsofthe study.
CreativeCommonsAttributionLicense,which
permitsunrestricteduse,distribution,and
Materialsandmethods
reproductioninanymedium,providedtheoriginal
authorandsourcearecredited. Weevaluateddeceasedsubjectsaged30yearsorabove.Wedissectedandweightedthe
DataAvailabilityStatement:Datacontainpatient- PFandtheAVFandevaluatedtheatheroscleroticburdenintheaorta,aswellasthecarotid,
sensitivematerialandthereforeareavailableto coronary,andcerebralarteriesusingmorphometricmeasurements.Wealsoinvestigated
qualifiedresearcherswhohaveIRBapprovalafter
theinteractionofPFandAVFwithageregardingtheatheroscleroticburden.
agreeingtoamaterialtransferagreement.To
requestthesedata,pleasecontactMs.Marta
[email protected],data Results
areavailableviahttp://www2.fm.usp.br/gerolab/
Themeanageofthe240includedsubjectswas64.8±15.3years,and63%wasmale.
mostrahp.php?origem=gerolab&xcod=PLOS%
20Medicine&dequem=Paper%20datasets. GreaterPFwasassociatedwithahigherdegreeofaorticatherosclerosisafteradjustingfor
confoundingvariables(coefficient=4.39,95%CI=0.83;7.94,p=0.02).GreaterAVFwas
Funding:ANwassupportedbyascholarshipfrom
theCAPESFoundation,MinistryofEducationof associatedwithahighercoronarystenosisindex(coefficient=1.49,95%CI=0.15;2.83,p
PLOSONE|https://doi.org/10.1371/journal.pone.0186630 October16,2017 1/16
Systemicatherosclerosisandvisceralfat
Brazil(1074888)(http://www.capes.gov.br/).DSF-I =0.03)andagreaternumberofcoronaryplaques(coefficient=0.71,95%CI=0.24;1.19,p
wassupportedbyascholarshipfromtheFAPESP =0.003).WedidnotfindanassociationofPForAVFwithcarotidorcerebralatherosclerotic
(SaoPauloResearchFoundation,2013/12290-3)
burden.WefoundasignificantinteractionofAVF(coefficient=-0.08;95%CI=-0.14;-0.02,
(http://www.fapesp.br/).Thefundershadnorolein
studydesign,datacollectionandanalysis,decision p=0.009)andPF(coefficient=-0.87,95%CI=-1.70;-0.04,p=0.04)withageregarding
topublish,orpreparationofthemanuscript. carotidarteryatheroscleroticburden.
Competinginterests:Theauthorshavedeclared
thatnocompetinginterestsexist. Conclusions
GreaterAVFwasassociatedwithgreateratheroscleroticburdenandextentincoronary
arteries,whilegreaterPFcorrelatedwithahigherdegreeofatherosclerosisintheaorta.
Introduction
Since1980,theprevalenceofobesityhasmorethandoubledworldwide.In2014,39%ofadults
wereoverweightand13%wereobeseacrosstheglobe[1].Obesitymayberelatedtoathero-
sclerosisbyacomplexprocessthatmayinvolveachronicinflammatorystate,insulinresis-
tance,dyslipidemia,andhypertension[2].Previousepidemiologicalstudiesshowedan
associationofcoronaryarteryatherosclerosiswithepicardial[3],pericardial(PF)[4–6],and
abdominalvisceralfat(AVF)[7–9].PFconsistsofepicardialandparacardialfat,whichis
locatedbetweenthevisceralpericardiumandthemyocardium,andoutsideoftheparietal
pericardium,respectively[10].Theassociationbetweensubclinicalatherosclerosisasmea-
suredbycarotidarteryintima-mediathickness(CIMT)andAVF[11]orepicardialfat[12]
hasalsobeendescribed.Aorticatherosclerosisisassociatedwithepicardialfatthickness,but
PFwasnotevaluated[13].CerebralarteryplaquevolumeisassociatedwithAVF[14].Despite
suchevidence,allofthesestudiesusedimagingmethods[3–6,11–15],whichquantifiedvis-
ceralfatandatherosclerosisthroughindirectmeasurements.
Autopsystudiesarethegoldstandardforevaluatingtheassociationofvisceralfatwithath-
erosclerosis[16],allowingthedirectmeasurementofatherosclerosisandtheexactquantifica-
tionofvisceralfat[17].However,thefewautopsystudiesthathaveinvestigatedtheassociation
betweenvisceralfatandatherosclerosisrestrictedtheiranalysestocoronaryarteries[7,8,18–
20].Moreover,themajorityofthestudiesevaluatedWhiteyoungandmiddle-agedadults[7,
8,20,21].Furthermore,evidenceontheinfluenceofageontheassociationofPFandAVF
withsystemicatherosclerosisisscarce[11].Therefore,inthepresentstudyweinvestigatedthe
associationofPFandAVFwiththeseverityofatherosclerosisinmultiplearterialsites(aorta,
coronary,carotid,andcerebralarteries)inalargeautopsystudy.
Materialsandmethods
ThisstudywasconductedattheSaoPauloAutopsyServicefromUniversityofSaoPaulo
(Brazil).ItwasapprovedbytheEthicsCommitteeinResearchfromUniversityofSaoPaulo
MedicalSchoolandcompliedwiththe1975DeclarationofHelsinki.Thedeceased’snextof
kin(NOK)wasinformedaboutthisstudy,wasinvitedtoparticipate,andsignedawritten
informedconsentform.InthecityofSaoPaulo,autopsyiscompulsoryforindividualswhose
causeofnaturaldeathisunclear[22].FurtherdetailsaboutSaoPauloAutopsyServiceandthis
studycanbefoundelsewhere[23].During2011to2014,weincludedparticipantsaged30
yearsorabove.Theexclusioncriteriawereasfollows:(1)theNOKprovidedinconsistent
informationduringtheclinicalinterview;(2)theNOKhadlessthanweeklycontactwiththe
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Systemicatherosclerosisandvisceralfat
deceased;(3)theNOKwasunabletoparticipateduetoemotionalsuffering;(4)subjectswhohad
lost10%ormoreofregularweightduringthesixmonthspriortodeath;(5)arteriesorvisceralfat
wasretainedatautopsybythepathologist;(6)subjectswithpostmorteminterval(cid:21)24hours;and
(7)subjectswithsignsofbodyautolysisaccordingtotheCrossleycriteria[24].
Clinicalassessment
Informationaboutthesubject’ssociodemographicdata(age,sex,race,yearsofeducation,
maritalstatus,andsocioeconomicstatus[25])andcardiovascularriskfactors[hypertension,
diabetesmellitus,dyslipidemia,coronaryarterydisease(CAD),heartfailure,stroke,smoking,
alcoholuse,andphysicalinactivity]werecollectedfromthedeceased’sNOKthroughasemi-
structuredclinicalinterview[23,26].
Measurementofvisceralfat
ThehearttogetherwiththePFwaswashedinrunningwatertoremoveclots;then,fixedin
70%alcoholbyimmersionforatleast24hours,dissected,andweighed.Omental,mesenteric,
mesocolon,andperirenalfatweredissectedaftertheautopsyandweighedusingacalibrated
electronicscale.Toavoidmeasurementerror,wewereespeciallycarefultotarethescalebefore
usingit.Themeasurementswereexpressedingrams.AVFwasdeterminedbythesumofthe
omental,mesenteric,mesocolon,andperirenalfat.
Atherosclerosisevaluation
Wedissectedthefollowing:
1. Theaortafromtheascendingtotheabdominalsegmentbeforetheiliacbifurcation;
2. Thecommonandinternalcarotidarteries;
3. Thecoronaryarteries,includingtheleftmain,leftanteriordescendingandrightcoronary
arteryaswellasthecircumflexartery;and
4. Thecerebralarteries(e.g.,basilar,posterior,posteriorcommunicating,middle,anterior,
anteriorcommunicating,andinternalcarotidarteriesproximaltothecircleofWillis).
Allarterieswerewashedinrunningwatertoremoveclotsandfixedin70%alcoholbyimmer-
sionfor24hours.Gelatinwasinjectedinsidethevessellumenofthecarotid,coronary,andcere-
bralarteriestopreventarteryflatness.Thearterieswerethenstoredin10%formalin.
Subsequently,thecarotidandcoronaryarterieswerecutcross-sectionallyat5-mmintervals[27],
andthecerebralarterieswerecutat3-mmintervals.Wephotographedthelargestatheromapla-
queineacharteryusingastereomicroscope(Nikon1SMZ1000,NikonInst.,Tokyo,Japan).
Theareasdelineatedbytheoutervesselwallandbythelumenweremeasuredusingtheimage
softwareImageJ1(Fig1).Thestenosisindexwascalculatedbysubtractingthelumenareafrom
theouterarea,dividingthedifferencebytheouterarea,andmultiplyingtheresultby100[28].
Weusedthemeanstenosisindexofallmeasuredsectionsineachvesselbed(i.e.,coronary,
carotid,andcerebralarteries).Wealsocountedthenumberofatheroscleroticplaquesinthecere-
bralandcoronaryarteriesasameasurementofatheroscleroticdiseaseextent.
Weassessedinter-raterreliabilityofstenosisindexmeasurementsinarterialsegments.We
randomlyselected164segments,andtwoblindedindependentratersmeasuredthestenosis
index.Wecalculatedtheintraclasscorrelationcoefficient(ICC)usingtwo-waymixed-effects
model[29].Theinter-raterreliabilitywasexcellentwithanICCof0.962(95%CI=0.948;
0.972).
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Systemicatherosclerosisandvisceralfat
Fig1.Calculationofthestenosisindexinthecarotidartery.(A)Arealimitedbytheouterwallofthevessel.(B)
Lumenarea.Asimilarmethodwasusedtoevaluatecoronaryandcerebralarteries.
https://doi.org/10.1371/journal.pone.0186630.g001
Theaortawasopenedlongitudinallytoinvestigatetheseverityofatherosclerosisandthe
presenceofconfluentlesions.Atherosclerosisintheaortawasclassifiedasgrade1(plaques
werenotconfluent,andtherewerenoulcerationsandprotrusions);grade2(confluentareas
or/andanareaofulcerationwithminimalprotrusion);andgrade3(confluentplaques,multi-
focalulcerations,orprotrusions)(Fig2)[30].
Statisticalanalysis
Thesamplesizeof165subjectswasestimatedbasedonpreviousstudies[19]withapowerof
90%,analphaof5%,andaneffectsizeof0.24forthecorrelationbetweenanteriorepicardial
fatsurfaceandthescoreofcoronarystenosisinatwosided-test.However,weoptedtoinclude
240subjectstoinvestigatetheeffectmodificationbyage.
Wedefinedthedependentvariablesasthestenosisindexesincarotid,coronary,andcere-
bralarteries(continuousvariables);thenumberofatheroscleroticplaquesinthecoronaryand
cerebralarteries(discretevariables);andtheseverityofatherosclerosisintheaorta(ordinal
variable).TheindependentvariableswerethePFandAVFweights(continuousvariables).
Thesamplecharacteristicsweredescribedwithmeasurementsofcentraltendencyanddisper-
sionforquantitativevariablesorproportionsforqualitativevariables.
Theassociationofvisceralfatwiththestenosisindexesandthenumberofplaquesinthecor-
onary,carotid,andcerebralarterieswasassessedusinglinearregressionmodels.Theassocia-
tionofvisceralfatwiththeseverityofatherosclerosisintheaortawasassessedusingordinal
logisticregression.Weadjustedallmodelsforheight[31–34],whichwasusedasameasureof
theparticipant’ssize.Weadjustedthemultivariatemodelsforage,sex,smokingstatus,alcohol
use,physicalinactivity,hypertension,anddiabetesmellitus.Wealsoevaluatedthepossibilityof
interaction[11]betweenageandvisceralfatbycreatinganinteractiontermofagewithAVF
andPFandtestingitinregressionmodelsincoronary,carotidandcerebralarteriesadjusted
forthesamesetofvariablesdescribedabove.Thealphalevelwassetat0.05intwosided-tests.
WeusedStata/MP13(StataCorpLP,CollegeStation,Texas,USA)forthestatisticalanalyses.
Results
Among1,599eligiblesubjectsduringthestudyperiod,240metthecriteriaforthisstudy(Fig
3).Themeanageofthesubjectswas64.8±15.3years(range=30–98),151(63%)weremale,
147(61%)wereWhite,and197(82%)oftheNOKhaddailycontactwiththedeceased.The
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Fig2.Evaluationoftheseverityofatherosclerosisintheaorta.(A)Absenceofatherosclerosis.(B)Grade1,
non-confluentplaqueswithoutulcerationsandprotrusions.(C)Grade2,confluentareasor/andanareaof
ulcerationwithminimalprotrusion.(D)Grade3,confluentplaqueswithmultifocalulcerationsorprotrusions.
https://doi.org/10.1371/journal.pone.0186630.g002
maincauseofdeathwascardiovascularrelated116(48%)(Table1).Themeanweightofthe
AVFwas2,040±1,250g,andthemeanweightofthePFwas160±80g.Themeanstenosis
indexwas77.8±11.0%forcoronaryarteries,64.1±0.4%forcarotidarteries,and52.8±0.5%for
cerebralarteries.Themeannumberofplaqueswas6.3±3.8incoronaryarteries;and9.3±5.6in
cerebralarteries.Regardingtheseverityofaorticatherosclerosis,degrees2and3weremost
prevalent(40%eachone),andnosubjectwasdevoidofatherosclerosis.
Associationbetweenvisceralfatandaorticatherosclerosis
AVFwasnotassociatedwiththeseverityofaorticatherosclerosis(p=0.17),butgreaterPF
wasassociatedwiththeseverityofaorticatherosclerosisinthemultivariateanalysis(coeffi-
cient=4.39,95%CI=0.83;7.94,p=0.02)(Table2).
Associationbetweenvisceralfatandcoronaryarteryatherosclerosis
AgreateramountofAVFwasassociatedwithahigherstenosisindex(coefficient=1.49,95%
CI=0.15;2.83,p=0.03)andagreaternumberofplaquesincoronaryarteries(coefficient=
0.71,95%CI=0.24;1.19,p=0.003)inthemultivariateanalyses(Table2).However,therewas
nointeractionofAVFandageregardingtheatheroscleroticburden(p=0.47)(Fig4A),nor
ontheextentofatherosclerosis(p=0.68)incoronaryarteries(Fig5A)(Table3).Despitethe
lackofstatisticalsignificance,atrendwasnotedfortheassociationofPFwithcoronaryathero-
sclerosisasmeasuredbythestenosisindex(p=0.06)andwiththenumberofatherosclerotic
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Systemicatherosclerosisandvisceralfat
Fig3.Flowchartofstudypopulation.NOK=nextofkin;andPMI=postmorteminterval.
https://doi.org/10.1371/journal.pone.0186630.g003
plaques(p=0.05)(Table2).WedidnotobserveanyinteractionbetweenPFandageoncoro-
naryatheroscleroticburden(p=0.53)(Fig6A),noronitsextent(p=0.28)(Fig5C)(Table3).
Associationbetweenvisceralfatandcarotidarteryatherosclerosis
AVF(p=0.63)andPF(p=0.52)werenotassociatedwiththecarotidarterystenosisindex
(Table2)inmultivariateanalysis.However,weobservedaninteractionofagewithbothAVF
(coefficient=-0.08;95%CI=-0.14;-0.02,p=0.009)(Fig4B)andPF(coefficient=-0.87;95%
CI=-1.70;-0.04,p=0.04)(Fig6B)(Table3).Whilemiddle-agedadultsshowedaworseath-
eroscleroticburdenincarotidarterieswithincreasesinAVFandPF,weobservedaninverse
associationofcarotidarteryatheroscleroticburdenwiththeAVFandPFweightintheoldest
subjects.
Associationbetweenvisceralfatandcerebralarteryatherosclerosis
AVFwasnotassociatedwiththecerebralarterystenosisindex(p=0.53)norwiththenumber
ofcerebralarteryatheroscleroticplaquesafteradjustingforconfoundingfactors(p=0.23)
(Table2).WedidnotobserveaninteractionbetweenAVFandageoncerebralarteryathero-
scleroticburden(p=0.82)(Fig4C)noronitsdiseaseextent(p=0.52)(Fig5B)(Table3).Sim-
ilarly,multivariateanalysisshowedthatPFwasalsonotassociatedwiththestenosisindexin
cerebralarteries(p=0.83)norwiththenumberofplaques(p=0.83)(Table2).Theinteraction
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Systemicatherosclerosisandvisceralfat
Table1. Characteristicsofthesample(n=240).
Variable Mean(standarddeviation)orn(%)
Age(years) 64.8(15.3)
Male 151(62.9)
White 147(61.2)
Married 122(50.8)
Education(years),median(interquartilerange) 4(4)
Socioeconomicstatus(classes)a
.Upper 93(38.8)
.Middle 129(53.7)
.Lower 18(7.5)
Dailycontactofthenextofkinwiththedeceased 197(82.1)
Cardiovascularcauseofdeath 116(48.3)
Postmorteminterval(hours) 14.7(3.4)
Hypertension 163(67.9)
Diabetesmellitus 67(27.9)
Coronaryarterydisease 67(27.9)
Heartfailure 55(22.9)
Dyslipidemia 36(15.0)
Stroke 25(10.4)
Smoking
.Never 78(32.5)
.Current 90(37.5)
.Former 72(30.0)
Alcoholuse
.Never 85(35.4)
.Current 100(41.7)
.Former 54(22.5)
Physicalinactivity 149(62.1)
aSocioeconomicstatuswasdefinedaccordingtogrossfamilyannualincomeinUS$:Uppersocialclass:
(cid:21)6,783;Middle:3,256to6,782;Lower:(cid:20)3,255(1dollar=3.3BRL)
https://doi.org/10.1371/journal.pone.0186630.t001
betweenageandPFonatheroscleroticburden(p=0.87)(Fig6C)andonitsextent(p=0.54)
(Fig5D)wasnotsignificant(Table3).
Discussion
Ourstudyhasdemonstratedthattheassociationbetweenvisceralfatandatherosclerosisis
highlyvariabledependingonthelocationofvisceralfatandthevascularbed.WhilePFwas
associatedwithatheroscleroticburdenintheaortaandmarginallyassociatedwithcoronary
artery,AVFwasassociatedwithcoronaryarteryatherosclerosis.Ontheotherhand,visceral
fatwasnotassociatedwithatherosclerosisinthecerebralandcarotidarteries.Interestingly,
theeffectofvisceralfatoncarotidarteryatheroscleroticburdenseemstobemodifiedbyage.
Visceralfatseemstohavelocalandsystemiceffectsonatherosclerosispathophysiology
[35–37].Amongthesystemicinflammatoryeffects,macrophageinfiltrationwasfoundinthe
AVFinobeseindividuals[35].Thesecellsareinvolvedintheproductionofadipokines,which
arerelatedtometabolicsyndrome[38],andincreasedcardiovascularrisk[39].Previousimag-
ingstudieshaveshownthatlargerdepositsofAVFwereassociatedwithhighercalcification
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Systemicatherosclerosisandvisceralfat
Table2. Associationofvisceralfatwiththedegreeandextensionofatherosclerosis(n=240).
Arteries Model1a Model2b
Coef 95%CI p Coef 95%CI p
Stenosisindexordegreeofatherosclerosis
Aortac
AVF 0.20 0.001;0.40 0.05 0.18 -0.07;0.44 0.17
PF 5.65 2.61;8.69 <0.0001 4.39 0.83;7.94 0.02
Coronaryd
AVF 1.16 -0.01;2.33 0.05 1.49 0.15;2.83 0.03
PF 21.69 4.92;38.47 0.01 17.07 -0.85;34.99 0.06
Carotidd
AVF -0.10 -0.88;0.68 0.81 -0.23 -1.15;0.68 0.63
PF 0.60 -11.15;12.35 0.92 -4.13 -16.78;8.51 0.52
Cerebrald
AVF 0.38 -0.51;1.27 0.40 0.32 -0.69;1.34 0.53
PF 4.90 -7.99;17.80 0.45 1.49 -12.08;15.07 0.83
Numberofplaques
Coronaryd
AVF 0.69 0.28;1.10 0.001 0.71 0.24;1.19 0.003
PF 8.54 2.60;14.48 0.005 6.25 -0.13;12.63 0.05
Cerebrald
AVF 0.48 -0.13;1.10 0.12 0.41 -0.26;1.08 0.23
PF 7.06 -1.69;15.81 0.11 0.96 -7.96;9.88 0.83
Coef=coefficient;CI=confidenceinterval;AVF=abdominalvisceralfat;PF=Pericardialfat
aModel1:Adjustedforheight
bModel2:Adjustedforheight,age,sex,smoking,alcoholuse,physicalinactivity,hypertension,anddiabetesmellitus
cOrderedlogisticregression
dLinearregression
https://doi.org/10.1371/journal.pone.0186630.t002
scoresintheabdominalaorta[40,41],whichcontradictsourcurrentfindings.However,some
importantmethodologicaldifferencesneedtobehighlighted.First,weexaminedthewhole
aorta;andsecond,weevaluatedtheconfluence,ulceration,andprotrusionoftheplaques,
includingnon-calcifiedplaquecomponentsthatarenotrepresentedbythecalciumscore[30].
Ontheotherhand,wefoundthatAVFwasindeedassociatedwiththeburdenandextentof
coronaryarteryatherosclerosis,whichcorroboratespreviousimagingstudies[9,42].However,
thesestudiesdidnotevaluatetheatherosclerosisburdenasacontinuousvariable,butasacate-
goricalvariable.KortelainenandSarkiojawerethefirsttouseautopsymaterial,andtheyalso
foundanassociationbetweenAVFandcoronarynarrowing[7,8].However,inonestudy[20],
theydidnotfindanassociationbetweenAVFandtheextentofcoronaryatherosclerosis;andin
anotherstudy,theydidnotevaluatediseaseextent[7].Moreover,theirsampleswererestrictedto
middle-ageWhitesubjects[7,8,20].Ourresultsextendthisknowledgetoalargerandethnically
diversesamplewithawideragerange.Interestingly,noassociationwasnotedbetweenAVFand
carotidorcerebralarteryatherosclerosis.Thisfindingcontrastswithpreviousimaging-based
studies,whichfoundanassociationbetweenAVFandCIMT[11],aswellaswithtotalcerebral
arteryplaquevolume;however,thatstudywaslimitedbyasmallsamplesizeof25subjects,which
onlyallowedforunivariateanalysis[14].Inanotherstudy,AVFwasassociatedwithstenosisor
occlusionincerebralarteries;however,stenosiswasevaluatedasacategoricalvariableusingthe
cut-offof(cid:21)70%,andtheparticipantswereAsianandaged40yearsorolder[43].
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Systemicatherosclerosisandvisceralfat
Fig4.Predictedvaluesofthestenosisindexin(A)coronary,(B)carotid,and(C)cerebralarteries,
accordingtotheamountofabdominalvisceralfatcalculatedforparticipantswith40(blueline),60(green
line),and80(redline)yearsold,usinglinearregressionmodelsadjustedforheight,age,sex,smoking
status,alcoholuse,physicalinactivity,hypertension,anddiabetesmellitus,andincludinganinteraction
betweenageandabdominalvisceralfat.
https://doi.org/10.1371/journal.pone.0186630.g004
Ontheotherhand,theeffectofvisceralfatonatherosclerosismaynotbefullyexplainedby
systemiceffects.Infact,priordatasuggestthatepicardialfatcanlocallycontributetoatheroscle-
rosisbylipotoxicity,cytokinesecretion,andtheincreasedproductionofhemostaticfactors
[44],therebyinducinganinflammatoryresponsethatmayplayaroleincoronaryatherogenesis
[37,45].Previousstudieshavealreadydemonstratedthattheeffectofepicardialfatmayextend
toaorticatherosclerosisasmeasuredbythepercentageofobstructionbycomputedtomography
[13].Inourstudy,weobservedanassociationbetweenPFandtheseverityofaortaatherosclero-
sis.However,PFwasmarginallyassociatedwiththeburdenandextentofcoronaryarteryath-
erosclerosis.Mostofthepreviousimagingstudiesevaluatedonlytheepicardialfat[19,46]or
theepicardialandparacardialfatseparately[18],andfewstudiesevaluatedthePFitself[5,6].
Moreover,epicardialandparacardialfatwereestimatedindirectlyusingcomputedtomography
[5,6,18,46]orcomputerizedphotographsofthehearttoquantifytheepicardialfatthickness
andarea[19].Inaddition,analyseswereadjustedonlyforbodymassindex[18]orage[7]in
somestudies,whileweadjustedourregressionmodelsforamorecomprehensivesetofpossible
confoundingfactors.Moreover,coronaryarteryatherosclerosiswasevaluatedmacroscopically
insomeautopsystudies[18,19],insteadofusingmorerobustmorphometricmeasurements
suchastheonesthatweperformed.Finally,differencesinageandracecompositioncouldalso
explainthemarginalassociationbetweenPFandcoronaryarteryatherosclerosisinourstudy.
SincewecomparedAVFwithPFinthesameindividualsunderthesameconditions,and
adjustingforthesamesetofconfoundingfactors,ourresultssuggestAVFseemstohavemore
effectincoronaryarteryatherosclerosisthanPF.Therefore,coronaryarteryatherosclerosismay
PLOSONE|https://doi.org/10.1371/journal.pone.0186630 October16,2017 9/16
Systemicatherosclerosisandvisceralfat
Fig5.Predictedvaluesofthenumberofplaquesin(A)coronaryand(B)cerebralarteriesaccordingto
theamountofabdominalvisceralfat,andinthe(C)coronaryand(D)cerebralarteriesaccordingtothe
amountofpericardialfatforparticipantswith40(blueline),60(greenline),and80(redline)yearsold,
usinglinearregressionmodelsadjustedforheight,age,sex,smokingstatus,alcoholuse,physical
inactivity,hypertension,anddiabetesmellitus,andincludinganinteractionbetweenageandabdominal
visceralfatorpericardialfat.
https://doi.org/10.1371/journal.pone.0186630.g005
bemoreinfluencedbysystemicthanlocaleffects,whileaortaseemstobemoreinfluencedby
localeffects.WedidnotfindanassociationbetweenPFandcarotidorcerebralarteryathero-
sclerosis.Incontrast,previousstudieshavefoundanassociationbetweenCIMTandepicardial
fat[12,15],butdataregardingcerebralarterieswerenotfoundintheliterature.
Wewerealsoabletodemonstratetheeffectmodificationofageonboththeassociationof
AVFandPFwithcarotidarteryatherosclerosis.Whilewefoundapositiveassociationofvisceral
fatwithcarotidarteryatherosclerosisinyoungerindividuals,thisassociationbecamenegativein
olderadults.Althoughthismightberelatedtosurvivalbias,onemayspeculatewhethertheeffect
mightbevariableacrossdifferentagegroups.GreaterAVFandPFwererelatedtohighercoro-
naryatherosclerosisburden[5–9,18–20,46].Nevertheless,sinceCADmaydevelopbeforecarotid
atherosclerosis[47],individualswithgreaterAVFandPFmaydieearlierfromCAD,leadingtoa
reverseassociationbetweenvisceralfatandcarotidatherosclerosisinolderindividuals;sucha
phenomenonisknownasthe“obesityparadox”thathasbeendescribedinotherchronicdiseases
[48].However,longitudinalstudieswithmultiplemeasurementsofvisceralfatandcarotidartery
atherosclerosisacrossthelifespanwouldbenecessarytoconfirmthisfinding.Wedidnotobserve
aninteractionofagewithAVFandPFregardingatherosclerosisinthecoronaryandcerebral
arteries.Toourknowledge,theseinteractionswerenotevaluatedinpreviousstudies.
Theresultsofourstudyshouldbeinterpretedwithconsiderationofsomelimitations.First,
sincethiswasacross-sectionalstudy,wecouldnotestablishthecausalrelationshipbetween
visceraladiposityandsystemicatherosclerosis.Moreover,informationaboutcardiovascular
PLOSONE|https://doi.org/10.1371/journal.pone.0186630 October16,2017 10/16