Electrocardiography, AmbulatoryVentricular Premature ComplexesAutonomic Nervous SystemArrhythmias, CardiacHeart RateElectrocardiographyTachycardia, VentricularAtrial FibrillationEchocardiographyProspective StudiesAtrial Premature ComplexesRisk FactorsCardiac Complexes, PrematureDeath, Sudden, CardiacSyncopeSick Sinus SyndromeAnti-Arrhythmia AgentsTime FactorsSignal Processing, Computer-AssistedArrhythmia, SinusCatheter AblationCircadian RhythmFollow-Up StudiesTelemetryMyocardial IschemiaBradycardiaAtrioventricular BlockHeart Conduction SystemPacemaker, ArtificialMonitoring, PhysiologicPredictive Value of TestsTachycardia, SupraventricularExercise TestAutonomic Nervous System DiseasesMyocardial InfarctionAtrial FlutterTreatment OutcomePulmonary VeinsDeath, SuddenCardiac Pacing, ArtificialVentricular FibrillationTachycardia, Ectopic AtrialRecurrenceHeart DiseasesAngina Pectoris, VariantCardiomyopathy, HypertrophicTachycardiaElectrophysiologic Techniques, CardiacRadionuclide AngiographyLong QT SyndromeTape RecordingAmiodaronePrognosisDouble-Blind Method