title: Mechanism of syncope without prodromes with normal heart and normal electrocardiogram.
abstract: "Unexplained syncope, no prodromes, and normal heart" has been described as a distinct clinical and biological entity.
  
  
  
  The purpose of this study was to assess the mechanism of syncope.
  
  
  
  In this prospective multicenter study, 58 patients presenting with unexplained syncope, no prodromes, and a normal heart received an implantable loop recorder (ILR) and were followed up until a diagnosis was established. Their outcomes were compared with those of 389 patients affected by reflex syncope with prodromes who received an ILR.
  
  
  
  During a mean observation period of 16 ± 13 months, a diagnostic event was documented by the ILR in 29 patients (50%); an asystolic pause of 11 ± 5 seconds (range 3.5-22 seconds) was present at the time of the diagnostic event in 19 patients (66%). Compared with patients affected by reflex syncope with prodromes, patients with unexplained syncope, no prodromes, and a normal heart more frequently had an asystolic syncope (66% vs 47%; P = .001), and this was more frequently due to idiopathic paroxysmal atrioventricular block (47% vs 21%; P = .04). Ten patients with asystolic pauses underwent cardiac pacing, and 8 patients underwent oral theophylline treatment. During the subsequent 17 ± 12 months of follow-up, syncope recurred in 1 patient on theophylline and presyncope occurred in 1 patient with pacemaker.
  
  
  
  A long asystolic pause, frequently due to idiopathic paroxysmal atrioventricular block, played a role in the mechanism of syncope in two-thirds of patients who had electrocardiographic documentation of a diagnostic event. When a specific therapy was administered in patients with asystolic syncope, the short outcome was favorable.
authors.affiliation: Department of Cardiology, Ospedali del Tigullio, Lavagna, Italy. Electronic address: mbrignole@asl4.liguria.it.
authors.forename: Michele
authors.initials: M
authors.lastname: Brignole
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Université de la Méditerranée, Ministère de la Défense, Marseille, France and Laboratory of Biochemistry and Molecular Biology, Timone University Hospital, Marseille, France.
authors.forename: Regis
authors.initials: R
authors.lastname: Guieu
authors.affiliation: Department of Cardiology, Ospedale Generale Regionale, Bolzano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tomaino
authors.affiliation: Department of Cardiology, Arcispedale S. Maria Nuova, Reggio Emilia, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Iori
authors.affiliation: Department of Geriatrics, Ospedale Careggi, Firenze, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ungar
authors.affiliation: Department of Cardiology, Ospedali del Tigullio, Lavagna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bertolone
authors.affiliation: Department of Cardiology, Ospedale Generale Regionale, Bolzano, Italy.
authors.forename: Matthias
authors.initials: M
authors.lastname: Unterhuber
authors.affiliation: Department of Cardiology, Arcispedale S. Maria Nuova, Reggio Emilia, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Bottoni
authors.affiliation: Department of Geriatrics, Ospedale Careggi, Firenze, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tesi
authors.affiliation: Department of Cardiology, Timone University Hospital, Marseille, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Claude Deharo
mesh_terms: D000368:Aged; D054537:Atrioventricular Block / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods; D015716:Electrocardiography, Ambulatory / Q000379:methods; D005260:Female; D006323:Heart Arrest / Q000150:complications / Q000175:diagnosis / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D013575:Syncope / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000628:therapy; D013806:Theophylline / Q000008:administration & dosage*; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D013806:Theophylline
keywords: Adenosine; Cardiac pacing; Implantable loop recorder; Syncope; Theophylline