Ventricular20Hypertrophy.docx

Ventricular20Hypertrophy.docx

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Ventricular20Hypertrophy

Hypertension.1997;29:

706-714.）

EffectofAfrican-AmericanRaceandHypertensiveLeftVentricularHypertrophyonCoronaryVascularReactivityandEndothelialFunction

JanL.Houghton;VivienneE.Smith;DavidS.Strogatz;NancyL.Henches;WarrenM.Breisblatt;AlbertA.Carr

theDivisionofCardiology,DepartmentofMedicine,Albany（NY）MedicalCollege（J.L.H.,V.E.S.,N.L.H.,W.M.B.）;SchoolofPublicHealth,StateUniversityofNewYorkatAlbany（D.S.S.）;andAugusta（Ga）PreventiveCardiology,PC（A.A.C.）.

Abstract

ExcesscardiovascularmorbidityandmortalityamongAfrican（black）Americansremainsanimportantyetunexplainedpublichealthproblem.OnepossibleexplanationproposesthatintrinsicoracquiredabnormalitiesincoronaryvascularreactivityandendothelialfunctionresultinexcessischemiaamongblackAmericans.Toexaminethishypothesis,wesubjected80individualswithnormalcoronaryarteriestoinvasivetestingofcoronaryarteryandmicrovascularrelaxationusingintracoronaryinfusionsofacetylcholineandadenosine,aDopplertippedintracoronaryguidewire,andquantitativecoronaryangiography.Wemeasuredthepercentincreaseincoronarybloodflowandepicardialdiameteraftergradedinfusionofintracoronaryacetylcholineandincoronarybloodflowafterintracoronaryadenosinein31normotensivesubjects（10black,21white）and49hypertensivesubjectswithleftventricularhypertrophy（25black,24white）.Categoricalandmultivariateanalysesrevealedthatinresponsetointracoronaryadenosineandacetylcholine,thedepressioninendothelium-independentand-dependentmicrovascularrelaxationduringpeakagonisteffectwaslargelyrelatedtothepresenceofchronichypertensionandleftventricularhypertrophy.Normotensivesubjectsdemonstratednointrinsicracialdifferencesinconduitandresistancevesselvasoreactivity.Inresponsetomaximalinfusionofacetylcholine,epicardialcoronaryarteriesconstrictedsimilarlyinblackandwhitesubjectswithhypertensiveleftventricularhypertrophyanddilatedsimilarlyinnormotensiveblackandwhitesubjects.Thus,ourstudyshowsthatinacohortofblackandwhitesubjectsreferredforcoronaryarteriographybecauseofchestpain,AfricanAmericanraceisnotassociatedwithexcessintrinsicoracquireddepressionincoronaryvascularrelaxationduringthepeakeffectoftheendothelium-dependentand-independentagonistsacetylcholineandadenosine,afteradjustmentforthepresenceofleftventricularhypertrophy.

KeyWords:

blacks•race•vasorelaxation•hypertrophy,leftventricular•vascularreactivity•endothelialfunction

Introduction

ExcesscardiovascularmorbidityandmortalityamongAfrican（black）Americansremainsanimportantyetunexplainedpublichealthproblem.12Furthermore,theparadoxicalfindingofalesserdegreeofcoronaryatherosclerosisbutworseprognosisafterdiagnosisofischemicheartdiseaseexistsamongblackAmericans.34Althoughmyocardialischemiaisgenerallysecondarytocoronaryarteryatherosclerosis,thedemonstrationofischemiawithnormalcoronaryarteries（syndromeX,aorticstenosis,leftventricularhypertrophy[LVH]）hasclarifiedtheconceptsofmicrovascularanginaandnonatheroscleroticsupply/demandmismatch.56789Theseconcepts,togetherwithanevolvingunderstandingoftheendothelium,justifyinvestigationsthatemphasizethecentralimportanceofthecoronarymicrocirculationandendotheliumintheregulationofmyocardialperfusion.1011

Anumberofpossibleexplanationshavebeenadvancedtoaddresstheperceivedparadoxofgreatermyocardialischemiadespitelessatheroscleroticdiseaseamongblacks.Oneinvokessocietal-basedfactorsrelatedtosocioeconomicstatus,suchasaccesstomedicalcare,complianceissues,andthedurationofuntreatedorpoorlytreatedcardiovasculardisease.121314AsecondexplanationproposesthatcomorbiddiseasesorprocessesmoreprevalentinblackAmericans,suchashypertensionanddiabetesmellitus,mayaugmentischemiabyaffectingsupplyanddemandthroughmechanismsotherthanatherosclerosis.6151617Third,intrinsicabnormalitiesinthecoronaryendotheliumandmicrocirculationmaybepresentinblackAmericans,possiblyaspartofageneralizeddefectinvascularrelaxation,thusleadingtoabnormalperfusionofthemyocardiumintheabsenceofatherosclerosis.1819

OurpurposeinthisstudywastoexaminetheeffectsofhypertensiveLVHandraceoncoronaryarteryandarteriolarvasorelaxationinresponsetotheendothelium-dependentagentacetylcholineandthepredominantlyendothelium-independentagentadenosineinacohortofblackandwhiteAmericanswithangiographicallynormalcoronaryarteries.Comparisonsweremadeamongnormotensivesubjectsandsubjectswithcomplicatedhypertension,definedashypertensionplusLVH.Studysubjectswereidentifiedforpossibleparticipationafterclinicalreferralforcardiaccatheterizationbecauseofsuspectedischemicheartdisease.

Methods

Subjects

Subjectswereprospectivelyrecruitedfortheapprovedinvestigationalstudy（AlbanyMedicalCollegeInstitutionalReviewBoard）afterclinicalreferralforcardiaccatheterizationforevaluationofchestpain.Informedconsentwasobtained,whichdocumentedtheparticipants'understandingoftheinvestigationalnatureoftheprotocol.Thecurrentstudyispartofalargerstudywhosepurposeisexaminationoftheeffectsofhypertension,LVH,hemodynamicallyinsignificantatherosclerosis,sex,andethnicityoncoronaryarteryandarteriolarrelaxation.Enrolledsubjectshadnormalepicardialcoronaryarteriesdocumentedduringcoronaryangiography.Individualswereexcludedfromthestudyiftheyhadahistoryofmyocardialinfarction,balloonangioplasty,bypasssurgery,significantvalvularheartdisease,orotherseriousmedicaldisorder.Subjectsfastedforaminimumof8hoursbeforethestudy.Currentsmokerswereinstructedtorefrainfromsmokingforaminimumof8hours.

SubjectsweregroupedbyraceandpresenceofhypertensiveLVH.Hypertensionwasdefinedasreproduciblebloodpressuremeasurementsgreaterthanorequalto140/90mmHgorself-reportedtakingofantihypertensivemedication.Diabetesmellituswasdiagnosedbyself-reportedhistoryorfastingserumglucosegreaterthan7.8mmol/L（140mg/dL）.

Allsubjectswerereferredforcardiaccatheterizationforevaluationofchestpainorananginaequivalent.Chestpainwasclassifiedasanginapectoris,atypicalangina,ornoncardiacchestpain.Anginapectoriswasdefinedintheclassicmannerassubsternalchestdiscomfort（heavinessorpressure）broughtonbyexertionandrelievedbyrestornitroglycerinoraprolongedepisodeofanginalpainatrestrequiringhospitalization.Atypicalanginawasdefinedaschestpainwithsomefeaturesofclassicanginabutothercharacteristicsnotgenerallyassociatedwithanginapectoris,suchasasharporpleuriticcharacterorintermittentrelationshiptoexercise.Noncardiacchestpainhadnofeaturesofanginaotherthanasubsternallocationofchestpain.Ananginaequivalentwasdefinedassymptomsorfindingscommonlyassociatedwithischemiaintheabsenceofchestpain,suchasdyspneaorheartfailure.Innormotensivesubjects,6black（60%）and13white（62%）werejudgedtohaveanginapectoris;2black（20%）and7white（33%）,atypicalangina;2black（20%）and0white,ananginalequivalent;and0blackand1white（5%）,noncardiacchestpain.InhypertensivesubjectswithLVH,13black（52%）and11white（46%）werejudgedtohaveanginapectoris;5black（20%）and9white（38%）,atypicalangina;6black（24%）and2white（8%）,ananginalequivalent;and1black（4%）and2white（8%）,noncardiacchestpain.

Twenty-nineof45whitesubjects（64%）and24of35blacksubjects（69%）weretakingmedicationsforchestpainand/orhypertension.Seventeenofthese29whitesubjects（59%）and12ofthese24blacksubjects（50%）weretakingdrugsexpectedtohavecoronaryvasodilatingpropertiesalone（nitroglycerinand/orcalciumchannelblockers）.Twowhite（7%）and1black（4%）subjectsweretakingaß-blockeralone.However,5white（17%）and6black（25%）subjectsweretakingbothaß-blockerandcoronaryvasodilator.Finally,theremaining5white（17%）and5black（21%）subjectsweretakinganangiotensin-convertingenzymeinhibitoror

-blockertogetherwithotherdrugs.Eightwhite（28%）and9black（38%）subjectsuseddiureticsinadditiontothemedicationsalreadydescribed.Wheneverpossible,vasoactiveandantihypertensivemedicationswerewithheldforaminimumof12hoursbeforethestudyalthoughthestudydesignpermittedsublingualnitroglycerinifdeemedclinicallynecessary;however,nosubjectrequiredsublingualnitroglycerinwithin4hours.In10of80studysubjects（5whiteand5black）,medicationswithvasoactivepotentialwereusedwithin12hoursbecauseofclinicalindication.Medicationsusedwithin12hourswereasfollows:

calciumchannelblockersin2whitesubjects,nitroglycerinpreparationsin2whiteand2blacksubjects,ashort-actingangiotensin-convertingenzymeinhibitorin1whitesubject,and2ormoredrugsin3blacksubjects.Therewerenosignificantracialdifferencesindrugusage.Socioeconomicstatuswasassessedbythreeindicators:

yearsofformaleducation,possessionofprivatemedicalinsurance,andcurrentemploymentstatus.Bodymassindexwascalculatedasweight（inkilograms）dividedbyheight（inmeters）squared.Bloodwasobtainedwithsubjectsinthefastingstateformeasurementoftotalcholesterol,low-densityandhigh-densitylipoproteincholesterols,lipoprotein（a）,andglucose.

LeftVentricularMassMeasurements

Leftventricular（LV）masswascalculatedwithM-