Electrocardiography, AmbulatoryVentricular Premature ComplexesHeart RateElectrocardiographyArrhythmias, CardiacMyocytes, CardiacHeartDeath, Sudden, CardiacHeart Conduction SystemCardiac OutputHeart DiseasesMyocardial InfarctionAtrial Premature ComplexesSignal Processing, Computer-AssistedEchocardiographyCardiac Pacing, ArtificialAtrial FibrillationTachycardia, VentricularCardiac Complexes, PrematureAutonomic Nervous SystemVectorcardiographySyncopeHeart VentriclesCardiac Surgical ProceduresTime FactorsAnti-Arrhythmia AgentsLong QT SyndromePredictive Value of TestsBrugada SyndromeProspective StudiesMyocardial IschemiaVentricular FibrillationTelemetryTachycardiaExercise TestBundle-Branch BlockArrhythmia, SinusCardiac CatheterizationFollow-Up StudiesMyocardiumBradycardiaHeart BlockCardiomegalyCardiomyopathiesHeart FailureMonitoring, PhysiologicPacemaker, ArtificialAtrioventricular BlockSick Sinus SyndromeDeath, SuddenElectrophysiologic Techniques, CardiacCardiomyopathy, HypertrophicTreatment OutcomeCatheter AblationMyocardial ContractionSensitivity and SpecificityHeart AtriaBlood PressureStroke VolumeChest PainCoronary DiseaseVentricular Function, LeftVentricular Dysfunction, LeftRisk FactorsDiagnosis, Computer-AssistedHeart ArrestHemodynamicsPrognosisTachycardia, SupraventricularCardiomyopathy, DilatedAngina PectorisCardiac TamponadeRetrospective StudiesHypertrophy, Left VentricularPhonocardiographyCoronary AngiographyBody Surface Potential MappingRisk AssessmentAtrial FlutterCreatine KinaseAutonomic Nervous System DiseasesTachycardia, ParoxysmalReproducibility of ResultsTroponin IAmiodaroneModels, CardiovascularPericarditisVentricular DysfunctionCardiac VolumeAdrenergic beta-AntagonistsDogsVentricular FunctionDefibrillators, ImplantableHeart Function TestsCardiac Resynchronization TherapyAngina Pectoris, Variant