Heart FailureVentricular Function, LeftHeartPerfusionVentricular Dysfunction, LeftStroke VolumeHeart RateVentricular Function, RightEchocardiographyHeart VentriclesMyocardiumVentricular FunctionMyocytes, CardiacMyocardial ContractionHemodynamicsCardiac Output, LowMyocardial InfarctionCardiac OutputHeart DiseasesCardiomyopathy, DilatedPerfusion ImagingTime FactorsVentricular RemodelingSystoleHeart Function TestsCardiac Pacing, ArtificialTreatment OutcomeHeart Failure, SystolicElectrocardiographyCardiomyopathiesDiastoleCardiotonic AgentsMyocardial IschemiaMyocardial Perfusion ImagingHeart TransplantationNatriuretic Peptide, BrainProspective StudiesCoronary CirculationHeart Failure, DiastolicFollow-Up StudiesArrhythmias, CardiacCardiomegalyCardiac CatheterizationVentricular Dysfunction, RightExercise TestAdrenergic beta-AntagonistsEchocardiography, DopplerCardiac Surgical ProceduresHeart Defects, CongenitalDogsBlood PressureChronic DiseaseHypertrophy, Left VentricularCoronary DiseasePredictive Value of TestsDeath, Sudden, CardiacTomography, Emission-Computed, Single-PhotonRadionuclide VentriculographyVentricular PressureGated Blood-Pool ImagingPrognosisCardiac VolumeHeart AtriaDisease Models, AnimalVentricular DysfunctionTreatment FailureRisk FactorsRadionuclide AngiographyRetrospective StudiesDobutamineHeart-Assist DevicesAngiotensin-Converting Enzyme InhibitorsSeverity of Illness IndexOxygen ConsumptionPropanolaminesBiological MarkersExercise TolerancePacemaker, ArtificialMagnetic Resonance Imaging, CineRats, Sprague-DawleyCoronary AngiographyMyocardial Reperfusion InjuryAtrial Natriuretic FactorBlood Flow VelocityFibrosisVascular ResistanceFetal HeartCoronary VesselsTechnetium Tc 99m SestamibiMyocarditisMitral Valve InsufficiencyRisk AssessmentDiureticsVentriculography, First-PassRegional Blood FlowMyocardial ReperfusionRats, WistarReproducibility of ResultsHeart BlockCardiovascular Agents