Defibrillators, ImplantableHeart FailureDefibrillatorsTachycardia, VentricularElectric CountershockVentricular FibrillationDeath, Sudden, CardiacArrhythmias, CardiacAnti-Arrhythmia AgentsAmiodaroneCardiac Pacing, ArtificialPacemaker, ArtificialEquipment FailureStroke VolumeHeartVentricular Dysfunction, LeftCardiac Output, LowTreatment OutcomeHeart ArrestCardiac Resynchronization TherapyElectrocardiographyFollow-Up StudiesEquipment DesignHeart RateSyncopeHeart Failure, SystolicTachycardiaAdrenergic beta-AntagonistsVentricular Function, LeftProspective StudiesElectrodes, ImplantedHeart-Assist DevicesDeath, SuddenTime FactorsSotalolCardiomyopathy, DilatedCardiac Resynchronization Therapy DevicesSurvival RateRetrospective StudiesNatriuretic Peptide, BrainRisk FactorsRisk AssessmentChronic DiseaseHeart Failure, DiastolicExercise TestElectric InjuriesSurvival AnalysisHeart TransplantationEchocardiographyExercise ToleranceVentricular RemodelingEquipment SafetyPropanolaminesRandomized Controlled Trials as TopicPrognosisHemodynamicsCardiomyopathiesMulticenter Studies as TopicPredictive Value of TestsDevice RemovalHeart DiseasesHydrazonesCardiotonic AgentsTelemetryAngiotensin-Converting Enzyme InhibitorsProsthesis ImplantationHospitalizationMyocardiumImplantable NeurostimulatorsCheyne-Stokes RespirationHeart VentriclesElectrocardiography, AmbulatoryCarbazolesSeverity of Illness IndexRegistriesVentricular DysfunctionCardiography, ImpedanceCost-Benefit AnalysisProstheses and ImplantsEquipment Failure AnalysisPatient ReadmissionDiureticsSystoleKaplan-Meier EstimateSleep Apnea, CentralBundle-Branch BlockProportional Hazards ModelsOxygen ConsumptionRecurrenceHeart Function TestsCardiovascular AgentsMyocardial IschemiaMonitoring, PhysiologicAtrial FibrillationBiological MarkersTreatment FailureMyocardial ContractionKidney Failure, ChronicMyocardial InfarctionEchocardiography, Doppler