title: High incidence of tachyarrhythmias detected by an implantable loop recorder in patients with unexplained syncope.
abstract: BACKGROUND
  Syncope is a complex clinical syndrome that may be challenging with respect to a definite diagnosis. The implantable loop recorder (ILR) is a useful tool to define but also to exclude an arrhythmic aetiology.
  
  
  OBJECTIVE
  To investigate the causes of recurrent syncope or near-syncope with respect to underlying arrhythmias in non-selected consecutive patients monitored with an ILR.
  
  
  METHODS
  A retrospective study was conducted including 55 patients (34 men, 21 women; age 60+/-19 years) with unexplained syncope who received an ILR for prolonged monitoring at our institution between April 1998 and October 2006.
  
  
  RESULTS
  Forty (73%) patients had a recurrence of syncope or near-syncope. Structural heart disease was present in 18 (33%) patients, 4 of them having an ejection fraction <35%. An arrhythmia was detected as the cause of syncope in 25 (46%) patients. The ILR was successful in establishing a symptom-rhythm correlation in 63%. The mean follow-up period from implantation to occurrence of the detected arrhythmias was 9+/-8 months. Bradyarrhythmias were recorded in 12 (22%) patients, whereas tachyarrhythmias were found in 13 (24%) patients. Narrow QRS tachycardia was the underlying arrhythmia in 6 patients and wide QRS tachycardia in 7 patients. A pacemaker was implanted in all 12 patients with bradyarrhythmias. Implantable cardioverter defibrillator (ICD) therapy was indicated in 6 patients with adjunctive catheter ablation in 3 of them. Four patients presenting with paroxysmal supraventricular tachycardia were treated with radiofrequency catheter ablation.
  
  
  CONCLUSIONS
  The ILR helped efficaciously to determine the correct diagnosis and appropriate treatment of recurrent syncope. A considerably high proportion of tachyarrhythmias was detected in this non-selected consecutive population. The majority of patients with tachyarrhythmic syncope required defibrillator implantation and/or radiofrequency ablation.
authors.affiliation: Paracelsus Private Medical University, Salzburger Landeskliniken, St. Johanns-Spital, Department of Cardiology, Muellner Hauptstrasse 48, A-5020 Salzburg, Austria. c.schernthaner@tele2.at
authors.forename: Christina
authors.initials: C
authors.lastname: Schernthaner
authors.forename: Franz
authors.initials: F
authors.lastname: Danmayr
authors.forename: Johann
authors.initials: J
authors.lastname: Altenberger
authors.forename: Maximilian
authors.initials: M
authors.lastname: Pichler
authors.forename: Bernhard
authors.initials: B
authors.lastname: Strohmer
mesh_terms: D000328:Adult; D000368:Aged; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013575:Syncope / Q000209:etiology*; D013610:Tachycardia / Q000150:complications / Q000175:diagnosis*; D016896:Treatment Outcome