Heart FailureVentricular Function, LeftHeartTachycardiaTachycardia, VentricularVentricular Dysfunction, LeftStroke VolumeHeart RateElectrocardiographyVentricular Function, RightCardiac Pacing, ArtificialHeart VentriclesTachycardia, SupraventricularAnti-Arrhythmia AgentsArrhythmias, CardiacEchocardiographyDefibrillators, ImplantableVentricular FunctionMyocytes, CardiacDeath, Sudden, CardiacMyocardiumMyocardial ContractionMyocardial InfarctionCardiomyopathy, DilatedCardiac Output, LowHeart AtriaHemodynamicsFollow-Up StudiesTreatment OutcomeTachycardia, Ectopic AtrialTime FactorsCardiac OutputHeart DiseasesAtrial FibrillationProspective StudiesVentricular RemodelingVentricular FibrillationCardiac Surgical ProceduresAmiodaroneSystoleHeart Function TestsMyocardial IschemiaHeart Failure, SystolicCardiomyopathiesDiastoleDogsCardiotonic AgentsHeart TransplantationNatriuretic Peptide, BrainHeart Failure, DiastolicCardiomegalyVentricular Dysfunction, RightPredictive Value of TestsPacemaker, ArtificialCardiac CatheterizationAtrial FlutterAdrenergic beta-AntagonistsBradycardiaEchocardiography, DopplerElectrophysiologic Techniques, CardiacHeart Conduction SystemHeart Defects, CongenitalRetrospective StudiesTetralogy of FallotPrognosisChronic DiseaseHypertrophy, Left VentricularSotalolCatheter AblationRisk FactorsDisease Models, AnimalExercise TestElectrocardiography, AmbulatoryRadionuclide VentriculographyVentricular PressureBlood PressureCardiac VolumeCoronary DiseaseVentricular DysfunctionTreatment FailureElectric CountershockCoronary CirculationGated Blood-Pool ImagingRisk AssessmentHeart-Assist DevicesRadionuclide AngiographyAngiotensin-Converting Enzyme InhibitorsRecurrencePropanolaminesPostoperative ComplicationsSeverity of Illness IndexBiological MarkersDobutamineSurvival AnalysisExercise ToleranceOxygen ConsumptionAtrial Natriuretic FactorLong QT SyndromeFetal HeartFibrosis