SyncopeDeath, SuddenSyncope, VasovagalDeath, Sudden, CardiacSudden Infant DeathCause of DeathArrhythmias, CardiacCell DeathElectrocardiographyTachycardia, VentricularCardiomyopathy, HypertrophicElectrocardiography, AmbulatoryLong QT SyndromeVentricular FibrillationDefibrillators, ImplantableBradycardiaAutopsyDeathFollow-Up StudiesRisk FactorsPacemaker, ArtificialHeart BlockAnti-Arrhythmia AgentsHeart ArrestAjmalineBrugada SyndromeProspective StudiesHeart RateCardiac Pacing, ArtificialBundle-Branch BlockRecurrenceTachycardiaCoronary Vessel AnomaliesNAV1.5 Voltage-Gated Sodium ChannelHeart Conduction SystemCardiomyopathiesMidodrineKCNQ1 Potassium ChannelTime FactorsRetrospective StudiesArrhythmogenic Right Ventricular DysplasiaSportsAutonomic Nervous SystemSyndromeCardiac Complexes, PrematurePostureAdrenergic beta-AntagonistsIncidenceHeart DiseasesPrognosisElectrophysiologic Techniques, CardiacEther-A-Go-Go Potassium ChannelsRisk AssessmentTreatment OutcomeHeart FailureMyocardial InfarctionAmiodaroneCardiomyopathy, DilatedAtrioventricular BlockVentricular Premature ComplexesEchocardiographyAutonomic Nervous System DiseasesCardiac ElectrophysiologyPredictive Value of TestsSurvival AnalysisKCNQ Potassium ChannelsBrain DeathRiskFatal OutcomeUnconsciousnessJervell-Lange Nielsen SyndromeCarotid SinusBlood PressureRomano-Ward SyndromeMyocardiumForensic PathologyFludrocortisoneInfant, NewbornAge FactorsPotassium Channels, Voltage-GatedPedigreeTorsades de PointesAtrioventricular NodeVagus NerveElectric CountershockCohort StudiesFetal DeathStroke VolumeHeart VentriclesCoronary DiseaseSurvival RateMutationWolff-Parkinson-White SyndromeHemodynamicsSupine PositionMandatory TestingAutonomic DenervationMyocardial IschemiaMedical History TakingHeart