2023
Detection of Left Ventricular Systolic Dysfunction From Electrocardiographic Images
Sangha V, Nargesi A, Dhingra L, Khunte A, Mortazavi B, Ribeiro A, Banina E, Adeola O, Garg N, Brandt C, Miller E, Ribeiro A, Velazquez E, Giatti L, Barreto S, Foppa M, Yuan N, Ouyang D, Krumholz H, Khera R. Detection of Left Ventricular Systolic Dysfunction From Electrocardiographic Images. Circulation 2023, 148: 765-777. PMID: 37489538, PMCID: PMC10982757, DOI: 10.1161/circulationaha.122.062646.Peer-Reviewed Original ResearchMeSH KeywordsAdultElectrocardiographyHumansLongitudinal StudiesProspective StudiesVentricular Dysfunction, LeftVentricular Function, LeftConceptsLV systolic dysfunctionYale-New Haven HospitalVentricular systolic dysfunctionSystolic dysfunctionLV ejection fractionBrazilian Longitudinal StudyNew Haven HospitalEjection fractionCardiology clinicRegional hospitalLeft ventricular systolic dysfunctionCedars-Sinai Medical CenterAdult Health (ELSA-Brasil) cohort
2020
Implications of Abnormal Exercise Electrocardiography With Normal Stress Echocardiography
Daubert MA, Sivak J, Dunning A, Douglas PS, Coyne B, Wang TY, Mark DB, Velazquez EJ. Implications of Abnormal Exercise Electrocardiography With Normal Stress Echocardiography. JAMA Internal Medicine 2020, 180: 494-502. PMID: 31985749, PMCID: PMC6990669, DOI: 10.1001/jamainternmed.2019.6958.Peer-Reviewed Original ResearchMeSH KeywordsCoronary DiseaseEchocardiography, StressElectrocardiographyExercise TestFemaleHumansMaleMiddle AgedPrognosisConceptsNormal stress echocardiographyComposite end pointStress echoExercise electrocardiographyStress echocardiographyMyocardial infarctionDownstream testingEnd pointDuke University Medical CenterExercise stress echoNegative exercise ECGStress ECG findingsAdverse cardiac eventsIncremental prognostic valueObservational cohort studyAdverse clinical eventsCoronary artery diseaseIndividual adverse eventsPopulation of patientsUniversity Medical CenterImaging resultsCoronary revascularizationAdverse eventsCardiac eventsCohort study
2018
Impaired Recovery of Left Ventricular Function in Patients With Cardiomyopathy and Left Bundle Branch Block
Sze E, Samad Z, Dunning A, Campbell KB, Loring Z, Atwater BD, Chiswell K, Kisslo JA, Velazquez EJ, Daubert JP. Impaired Recovery of Left Ventricular Function in Patients With Cardiomyopathy and Left Bundle Branch Block. Journal Of The American College Of Cardiology 2018, 71: 306-317. PMID: 29348023, PMCID: PMC8352572, DOI: 10.1016/j.jacc.2017.11.020.Peer-Reviewed Original ResearchConceptsGuideline-directed medical therapyLeft bundle branch blockCardiac resynchronization therapyWide QRS durationBundle branch blockQRS durationLVEF improvementQRS morphologyReduced LVEFBranch blockLeft ventricular ejection fraction improvementVentricular ejection fraction improvementEjection fraction improvementMean LVEF improvementNarrow QRS durationSevere valve diseaseFirst-line therapyHeart failure hospitalizationLeft ventricular functionVentricular assist deviceBaseline electrocardiographyFailure hospitalizationCombined endpointSignificant comorbiditiesResynchronization therapy
2017
Comparison of Incidence of Left Ventricular Systolic Dysfunction Among Patients With Left Bundle Branch Block Versus Those With Normal QRS Duration
Sze E, Dunning A, Loring Z, Atwater BD, Chiswell K, Daubert JP, Kisslo JA, Mark DB, Velazquez EJ, Samad Z. Comparison of Incidence of Left Ventricular Systolic Dysfunction Among Patients With Left Bundle Branch Block Versus Those With Normal QRS Duration. The American Journal Of Cardiology 2017, 120: 1990-1997. PMID: 28958452, DOI: 10.1016/j.amjcard.2017.08.003.Peer-Reviewed Original ResearchConceptsLeft ventricular systolic dysfunctionLeft bundle branch blockVentricular systolic dysfunctionBundle branch blockEjection fractionBaseline echocardiogramSystolic dysfunctionBranch blockQRS durationRisk factorsRelative riskLeft ventricular assist deviceNarrow QRS durationCohort of patientsNormal QRS durationFinal study cohortCommon risk factorsComparison of incidenceVentricular assist deviceHeart transplantStudy cohortLBBB patientsHigh incidencePatientsEchocardiogramRace and Sex Differences in QRS Interval and Associated Outcome Among Patients with Left Ventricular Systolic Dysfunction
Randolph TC, Broderick S, Shaw LK, Chiswell K, Mentz RJ, Kutyifa V, Velazquez EJ, Gilliam FR, Thomas KL. Race and Sex Differences in QRS Interval and Associated Outcome Among Patients with Left Ventricular Systolic Dysfunction. Journal Of The American Heart Association 2017, 6: e004381. PMID: 28320746, PMCID: PMC5523998, DOI: 10.1161/jaha.116.004381.Peer-Reviewed Original ResearchConceptsQRS durationBundle branch blockWhite patientsHeart failureBlack patientsBranch blockNon-left bundle branch block morphologyLeft ventricular systolic dysfunctionMultivariable Cox regression modelsBundle branch block morphologyLeft bundle branch blockMedian QRS durationVentricular systolic dysfunctionHeart failure patientsVentricular ejection fractionShorter QRS durationCox regression modelRisk of mortalityDuke University HospitalBlack individualsSex differencesCause mortalitySystolic dysfunctionCoronary angiographyEjection fraction
2016
Markers of Atherosclerosis, Clinical Characteristics, and Treatment Patterns in Heart Failure A Case-Control Study of Middle-Aged Adult Heart Failure Patients in Rural Kenya
Bloomfield GS, DeLong AK, Akwanalo CO, Hogan JW, Carter EJ, Aswa DF, Binanay C, Koech M, Kimaiyo S, Velazquez EJ. Markers of Atherosclerosis, Clinical Characteristics, and Treatment Patterns in Heart Failure A Case-Control Study of Middle-Aged Adult Heart Failure Patients in Rural Kenya. Global Heart 2016, 11: 97-107. PMID: 27102027, PMCID: PMC4843836, DOI: 10.1016/j.gheart.2015.12.014.Peer-Reviewed Original ResearchMeSH KeywordsAgedAnkle Brachial IndexAtherosclerosisBiomarkersCardiomyopathy, DilatedCase-Control StudiesDyslipidemiasEchocardiographyElectrocardiographyFemaleGuideline AdherenceHeart FailureHumansHypertensionKenyaLogistic ModelsMaleMiddle AgedMyocardial IschemiaOdds RatioPractice Guidelines as TopicRisk FactorsRural PopulationConceptsAnkle-brachial indexAtherosclerotic risk factorsIschemic heart failureHeart failureCase-control studyWall motion abnormalitiesRisk factorsMotion abnormalitiesAdult heart failure patientsHuman immunodeficiency virus (HIV) infectionA Case-Control StudyContribution of atherosclerosisImmunodeficiency virus infectionMarker of atherosclerosisHeart failure patientsMultivariable logistic regressionPhysical examination findingsConfidence intervalsRural KenyaIschemic patternLipid testingClinical characteristicsFailure patientsMost patientsExamination findings
2015
Genetic mutations in African patients with atrial fibrillation: Rationale and design of the Study of Genetics of Atrial Fibrillation in an African Population (SIGNAL)
Bloomfield GS, Temu TM, Akwanalo CO, Chen PS, Emonyi W, Heckbert SR, Koech MM, Manji I, Shen C, Vatta M, Velazquez EJ, Wessel J, Kimaiyo S, Inui TS. Genetic mutations in African patients with atrial fibrillation: Rationale and design of the Study of Genetics of Atrial Fibrillation in an African Population (SIGNAL). American Heart Journal 2015, 170: 455-464.e5. PMID: 26385028, PMCID: PMC4575772, DOI: 10.1016/j.ahj.2015.06.008.Peer-Reviewed Original ResearchConceptsValvular atrial fibrillationNonvalvular atrial fibrillationValvular heart diseaseAtrial fibrillationHeart diseaseCurrent tobacco smokingHistory of strokeCase-control studyGroup morbidityGenetic associationTobacco smokingSaharan AfricaMean ageAfrican patientsCardiovascular diseaseClinical phenotypingFibrillationPrimary analysisPatientsControl populationGenetic testingMorbidityDiseaseGenetic mutationsMost participantsInfluence of QRS infarct score and QRS duration prior to transcatheter aortic valve replacement on follow-up left ventricular end systolic volume in patients with new persistent left bundle branch block
Hannink LG, Wagner GS, Kisslo J, Alenezi FA, Shaw LK, Hofmann P, Zusterzeel R, Phelan M, Velazquez EJ, Gorgels AP. Influence of QRS infarct score and QRS duration prior to transcatheter aortic valve replacement on follow-up left ventricular end systolic volume in patients with new persistent left bundle branch block. Journal Of Electrocardiology 2015, 48: 637-642. PMID: 25959263, DOI: 10.1016/j.jelectrocard.2015.04.010.Peer-Reviewed Original ResearchMeSH KeywordsAged, 80 and overAortic Valve StenosisBundle-Branch BlockDiagnosis, Computer-AssistedEchocardiographyElectrocardiographyFemaleFollow-Up StudiesHumansMalePrognosisReproducibility of ResultsRetrospective StudiesRisk AssessmentSensitivity and SpecificityStroke VolumeTranscatheter Aortic Valve ReplacementTreatment OutcomeConceptsLeft bundle branch blockTranscatheter aortic valve replacementPersistent left bundle branch blockVentricular end-systolic volumeAortic valve replacementBundle branch blockEnd-systolic volumeQRS durationInfarct scoreValve replacementVentricular functionBranch blockNew-onset left bundle branch blockLeft ventricular end-systolic volumeNew left bundle branch blockLeft ventricular functionLarger study populationStrict inclusion criteriaSuch predictive valueQRS scoreSystolic volumeInclusion criteriaStudy populationCardiac conditionsPredictive valueOutcomes of Anatomical versus Functional Testing for Coronary Artery Disease
Douglas PS, Hoffmann U, Patel MR, Mark DB, Al-Khalidi HR, Cavanaugh B, Cole J, Dolor RJ, Fordyce CB, Huang M, Khan MA, Kosinski AS, Krucoff MW, Malhotra V, Picard MH, Udelson JE, Velazquez EJ, Yow E, Cooper LS, Lee KL. Outcomes of Anatomical versus Functional Testing for Coronary Artery Disease. New England Journal Of Medicine 2015, 372: 1291-1300. PMID: 25773919, PMCID: PMC4473773, DOI: 10.1056/nejmoa1415516.Peer-Reviewed Original ResearchConceptsObstructive coronary artery diseaseCoronary artery diseaseCTA groupSymptomatic patientsArtery diseaseComposite primary end pointPrimary end-point eventEnd pointRadiation exposureInvasive cardiac catheterizationMajor procedural complicationsPrimary end pointSecondary end pointsEnd-point eventsCumulative radiation exposureMedian followChest painUnstable anginaCardiac catheterizationMore patientsProcedural complicationsClinical outcomesRandomized trialsAnatomical testingMean age
2014
Platelet aggregation and mental stress induced myocardial ischemia: Results from the Responses of Myocardial Ischemia to Escitalopram Treatment (REMIT) study
Jiang W, Boyle SH, Ortel TL, Samad Z, Velazquez EJ, Harrison RW, Wilson J, Kuhn C, Williams RB, O’Connor C, Becker RC. Platelet aggregation and mental stress induced myocardial ischemia: Results from the Responses of Myocardial Ischemia to Escitalopram Treatment (REMIT) study. American Heart Journal 2014, 169: 496-507.e1. PMID: 25819856, PMCID: PMC4382806, DOI: 10.1016/j.ahj.2014.12.002.Peer-Reviewed Original ResearchConceptsMental stress-induced myocardial ischemiaIschemic heart diseaseSerotonin transporter expressionMyocardial ischemiaPlatelet aggregationPlatelet hyperactivityNormal left ventricular responseStable ischemic heart diseaseStress-induced myocardial ischemiaMental stressTransporter expressionAcute coronary syndromeLeft ventricular responseMental stress testMental stress testingCombination of serotoninEligible patientsCardiovascular eventsCardiovascular prognosisCoronary syndromeVentricular responsePlatelet activityHeart diseaseTreatment studiesIschemiaClinical outcome as a function of the PR-interval—there is virtue in moderation: data from the Duke Databank for cardiovascular disease
Holmqvist F, Thomas KL, Broderick S, Ersbøll M, Singh D, Chiswell K, Shaw LK, Hegland DD, Velazquez EJ, Daubert JP. Clinical outcome as a function of the PR-interval—there is virtue in moderation: data from the Duke Databank for cardiovascular disease. EP Europace 2014, 17: 978-985. PMID: 25164430, DOI: 10.1093/europace/euu211.Peer-Reviewed Original ResearchConceptsCoronary heart diseaseHeart diseaseDuke University Medical CenterMajor cardiovascular outcomesMajor cardiovascular eventsNative coronary arteriesUniversity Medical CenterPR interval durationCV eventsCardiovascular eventsCardiovascular outcomesCause mortalityCoronary angiographyDuke DatabankClinical outcomesAtrial fibrillationPoor outcomeCoronary arterySignificant stenosisSinus rhythmCardiovascular diseaseMedical CenterHigh riskPatientsRelevant covariatesPROspective Multicenter Imaging Study for Evaluation of chest pain: Rationale and design of the PROMISE trial
Douglas PS, Hoffmann U, Lee KL, Mark DB, Al-Khalidi HR, Anstrom K, Dolor RJ, Kosinski A, Krucoff MW, Mudrick DW, Patel MR, Picard MH, Udelson JE, Velazquez EJ, Cooper L, investigators P. PROspective Multicenter Imaging Study for Evaluation of chest pain: Rationale and design of the PROMISE trial. American Heart Journal 2014, 167: 796-803.e1. PMID: 24890527, PMCID: PMC4044617, DOI: 10.1016/j.ahj.2014.03.003.Peer-Reviewed Original ResearchConceptsCoronary artery diseasePROMISE trialAnatomical testingProspective Multicenter Imaging StudyDiagnostic strategiesInitial diagnostic strategyMajor procedural complicationsSubsequent care decisionsComposite of deathPrimary end pointLarge pragmatic trialClinical care teamQuality of lifeDiagnostic testing strategiesMultidetector coronaryChest painSymptomatic patientsUnstable anginaArtery diseaseProcedural complicationsRandomized trialsSymptomatic subjectsClinical effectivenessMyocardial infarctionPragmatic trial
2013
Depressive Symptoms and Mental Stress–Induced Myocardial Ischemia in Patients With Coronary Heart Disease
Boyle SH, Samad Z, Becker RC, Williams R, Kuhn C, Ortel TL, Kuchibhatla M, Prybol K, Rogers J, O’Connor C, Velazquez EJ, Jiang W. Depressive Symptoms and Mental Stress–Induced Myocardial Ischemia in Patients With Coronary Heart Disease. Psychosomatic Medicine 2013, 75: 822-831. PMID: 24163385, PMCID: PMC4378828, DOI: 10.1097/psy.0b013e3182a893ae.Peer-Reviewed Original ResearchConceptsMental stress-induced myocardial ischemiaCoronary heart diseaseLeft ventricular ejection fractionVentricular ejection fractionDepressive symptomsMyocardial ischemiaEjection fractionHeart diseaseMental Stress–Induced Myocardial IschemiaStress-induced myocardial ischemiaIschemic ST-segment changesBeck Depression Inventory-II scoresΒ-blocker withdrawalEpidemiologic Studies Depression ScaleFuture cardiovascular eventsMental stress testTreadmill exercise testST-segment changesWall motion abnormalitiesBeck Depression Inventory-IICardiovascular eventsII scoreTransthoracic echocardiographyAdult patientsUnadjusted analysesEffect of Escitalopram on Mental Stress–Induced Myocardial Ischemia: Results of the REMIT Trial
Jiang W, Velazquez EJ, Kuchibhatla M, Samad Z, Boyle SH, Kuhn C, Becker RC, Ortel TL, Williams RB, Rogers JG, O’Connor C. Effect of Escitalopram on Mental Stress–Induced Myocardial Ischemia: Results of the REMIT Trial. JAMA 2013, 309: 2139-2149. PMID: 23695483, PMCID: PMC4378823, DOI: 10.1001/jama.2013.5566.Peer-Reviewed Original ResearchConceptsMental stress-induced myocardial ischemiaStable coronary heart diseaseExercise-induced ischemiaCoronary heart diseaseMyocardial ischemiaHeart diseaseVentricular ejection fraction reductionStress-induced myocardial ischemiaMental stressRegional wall motion abnormalitiesEjection fraction reductionPlacebo-controlled trialST-segment depressionEffect of escitalopramTertiary medical centerWall motion abnormalitiesWeeks of escitalopramSignificant differencesEnd-point assessmentStressor taskEscitalopram groupCardiac eventsEscitalopram treatmentMore patientsTreat analysisPrevalence and Clinical Characteristics of Mental Stress–Induced Myocardial Ischemia in Patients With Coronary Heart Disease
Jiang W, Samad Z, Boyle S, Becker RC, Williams R, Kuhn C, Ortel TL, Rogers J, Kuchibhatla M, O'Connor C, Velazquez EJ. Prevalence and Clinical Characteristics of Mental Stress–Induced Myocardial Ischemia in Patients With Coronary Heart Disease. Journal Of The American College Of Cardiology 2013, 61: 714-722. PMID: 23410543, PMCID: PMC3913125, DOI: 10.1016/j.jacc.2012.11.037.Peer-Reviewed Original ResearchConceptsMental stress-induced ischemiaStress-induced ischemiaCoronary heart diseaseMental stress-induced myocardial ischemiaStable coronary heart diseaseStress-induced myocardial ischemiaExercise-induced ischemiaHeart diseaseMyocardial ischemiaClinical characteristicsHigh riskMental Stress–Induced Myocardial IschemiaExercise-induced myocardial ischemiaVentricular ejection fraction reductionRegional wall motion abnormalitiesEjection fraction reductionST-segment depressionMental stress testWall motion abnormalitiesUnmarried menEligible patientsPoor prognosisMotion abnormalitiesRisk factorsExercise test
2012
Race and gender variation in the QT interval and its association with mortality in patients with coronary artery disease: Results from the Duke Databank for Cardiovascular Disease (DDCD)
Williams ES, Thomas KL, Broderick S, Shaw LK, Velazquez EJ, Al-Khatib SM, Daubert JP. Race and gender variation in the QT interval and its association with mortality in patients with coronary artery disease: Results from the Duke Databank for Cardiovascular Disease (DDCD). American Heart Journal 2012, 164: 434-441. PMID: 22980312, DOI: 10.1016/j.ahj.2012.05.024.Peer-Reviewed Original ResearchConceptsCoronary artery diseaseCause mortalityArtery diseaseProlonged QTcRisk factorsQT intervalMortality riskLow glomerular filtration rateHigher diastolic blood pressureNative coronary artery stenosisCardiac risk factorsLow ejection fractionDiastolic blood pressureGlomerular filtration rateCoronary artery stenosisRisk of deathCardiac catheterizationCardiac eventsDuke DatabankBlood pressureEjection fractionQTc intervalQTc prolongationArtery stenosisBaseline electrocardiogramMechanisms and Predictors of Mitral Regurgitation after High-Risk Myocardial Infarction
Meris A, Amigoni M, Verma A, Thune JJ, Køber L, Velazquez E, McMurray JJ, Pfeffer MA, Califf R, Levine RA, Solomon SD, Investigators V. Mechanisms and Predictors of Mitral Regurgitation after High-Risk Myocardial Infarction. Journal Of The American Society Of Echocardiography 2012, 25: 535-542. PMID: 22305962, PMCID: PMC3501447, DOI: 10.1016/j.echo.2012.01.006.Peer-Reviewed Original ResearchMeSH KeywordsAdultAge FactorsAgedAngiotensin-Converting Enzyme InhibitorsCaptoprilDisease ProgressionEchocardiography, Doppler, ColorElectrocardiographyFemaleFollow-Up StudiesHumansMaleMiddle AgedMitral Valve InsufficiencyMonitoring, PhysiologicMultivariate AnalysisMyocardial InfarctionPredictive Value of TestsProspective StudiesReference ValuesReproducibility of ResultsRisk AssessmentROC CurveSeverity of Illness IndexSex FactorsStatistics, NonparametricStroke VolumeTetrazolesTime FactorsValineValsartanVentricular Dysfunction, LeftVentricular RemodelingConceptsHigh-risk myocardial infarctionBaseline mitral regurgitationMitral regurgitationMyocardial infarctionAtrial sizeIndependent predictorsCoaptation depthProgression of MRMitral valve deformationStructural valve diseaseSevere mitral regurgitationFunctional mitral regurgitationIschemic mitral regurgitationGood-quality echocardiogramsMitral annular areaMitral tentingMR degreeLV dysfunctionTenting areaBaseline characteristicsDiastolic functionHeart failureValve diseaseLV remodelingVentricular remodeling
2011
Predictors of systolic BP <140 mmHg and systolic BP level by randomly assigned treatment group (benazepril plus amlodipine or hydrochlorothiazide) in the ACCOMPLISH Study
Kjeldsen SE, Jamerson KA, Bakris GL, Pitt B, Dahlöf B, Velazquez EJ, Hua TA, Kelly RY, Zappe D, Hester A, Tuomilehto J, Östergren J, Ibsen H, Weber M, INVESTIGATORS F. Predictors of systolic BP <140 mmHg and systolic BP level by randomly assigned treatment group (benazepril plus amlodipine or hydrochlorothiazide) in the ACCOMPLISH Study. Blood Pressure 2011, 21: 82-87. PMID: 21830844, DOI: 10.3109/08037051.2011.598699.Peer-Reviewed Original ResearchConceptsSystolic blood pressureBetter SBP controlPrevious antihypertensive medicationsSBP controlAntihypertensive medicationsBaseline predictorsTreatment groupsHigher baseline systolic blood pressureCalcium channel blocker useUncontrolled systolic blood pressureHigher systolic blood pressureBaseline systolic blood pressureMain baseline predictorsUse of thiazidesSystolic BP levelsHigher diastolic BPMultivariable regression modelsLogistic regression modelsACCOMPLISH trialAmlodipine armRandomization armBlocker useCardiovascular outcomesInsulin useSystolic hypertension
2008
Left Ventricular Mechanical Dyssynchrony as Assessed by Phase Analysis of ECG‐Gated SPECT Myocardial Perfusion Imaging
Chen J, Garcia EV, Lerakis S, Henneman MM, Bax JJ, Trimble MA, Borges‐Neto S, Velazquez EJ, Iskandrian AE. Left Ventricular Mechanical Dyssynchrony as Assessed by Phase Analysis of ECG‐Gated SPECT Myocardial Perfusion Imaging. Echocardiography 2008, 25: 1186-1194. PMID: 18986406, DOI: 10.1111/j.1540-8175.2008.00782.x.Peer-Reviewed Original ResearchConceptsCardiac resynchronization therapyMyocardial perfusion imagingTissue Doppler imagingLV dyssynchronyPerfusion imagingTomography myocardial perfusion imagingSPECT myocardial perfusion imagingElectrocardiography-gated single-photon emissionSevere heart failureVentricular mechanical dyssynchronySingle photon emissionHeart failureMechanical dyssynchronyResynchronization therapyClinical evaluationDyssynchronyLeft ventricleDoppler imagingPatientsRegional wallMechanical contractionPhoton emissionCardiac cycleImportant predictorFourier harmonic functionsMeasuring left ventricular mechanical dyssynchrony from ECG-gated SPECT myocardial perfusion imaging.
Chen J, Garcia EV, Henneman MM, Bax JJ, Boogers MJ, Trimble MA, Borges-Neto S, Velazquez EJ, Iskandrian AE. Measuring left ventricular mechanical dyssynchrony from ECG-gated SPECT myocardial perfusion imaging. Minerva Cardioangiologica 2008, 56: 227-35. PMID: 18319701.Peer-Reviewed Original ResearchConceptsCardiac resynchronization therapyTissue Doppler imagingMyocardial perfusion imagingLV dyssynchronyECG-gated SPECT myocardial perfusion imagingPerfusion imagingCardiac resynchronization therapy (CRT) trialsMyocardial strain-rate imagingTomography myocardial perfusion imagingClinical validationAvailable echocardiographic techniquesSPECT myocardial perfusion imagingSevere heart failureVentricular mechanical dyssynchronyPredictors of responseRoutine clinical practiceStrain rate imagingSingle photon emissionEntire left ventricleHeart failureMechanical dyssynchronyResynchronization therapyEchocardiographic techniquesDyssynchronyClinical practice