title: Clinical impact of the implantable loop recorder in patients with isolated syncope, bundle branch block and negative workup: a randomized multicentre prospective study.
abstract: BACKGROUND
  Few studies have compared conventional testing with prolonged monitoring using an implantable loop recorder (ILR) following the first syncope episode in patients with bundle branch block (BBB) and negative workup.
  
  
  OBJECTIVE
  To compare two syncope evaluation strategies-primary use of an ILR (Group 1) versus conventional testing (Group 2)-and to estimate the prevalence of significant arrhythmias in the ILR patient subset.
  
  
  METHODS
  From January 2005 to December 2010, 78 patients admitted after one syncope episode were randomized to ILR (n=41) or conventional follow-up (n=37). Mean follow-up was 27 ± 12 months.
  
  
  RESULTS
  Mean age was 76 ± 8 years and 30 patients were women (38.5%); 18 presented cardiomyopathy (23%) and 12 had a history of atrial fibrillation (15.4%). Mean left ventricular ejection fraction was 56.5 ± 11% and mean His-to-ventricle interval was 55 ± 6ms based on negative electrophysiological study (EPS). Electrocardiogram abnormalities involved: 34 left bundle branch blocks (BBBs); 11 right BBBs; and 33 bifascicular blocks. Overall, 21 patients (27%) developed significant arrhythmic events: ventricular tachycardia (n=1; 1.3%); sudden death (n=2; 2.6%); third-degree atrioventricular (AV) block (n=14; 18%); sick sinus syndrome (n=4; 5.1%). In 19 (24.4%) patients, relevant arrhythmias were detected, with a significant difference between the ILR group (n=15/41; 36.6%) and the conventional follow-up group (n=4/37; 10.8%) (P=0.02). Eighteen patients were implanted with pacemakers; one received an implantable defibrillator. No predictors of AV block were identified in the ILR group.
  
  
  CONCLUSIONS
  In this randomized prospective study, the ILR strategy proved largely superior to conventional follow-up in detecting recurrent events, with a potential impact on therapeutic management. This observation highlights the usefulness of early monitoring in patients with BBB and negative EPS even after the first syncope episode but an empiric pacemaker strategy remains to be validated in this selected population.
authors.affiliation: Division of Cardiology, University Jean-Monnet, Saint-Étienne, France. antoine.dacosta@univ-st-etienne.fr
authors.forename: Antoine
authors.initials: A
authors.lastname: Da Costa
authors.forename: Pascal
authors.initials: P
authors.lastname: Defaye
authors.forename: Cécile
authors.initials: C
authors.lastname: Romeyer-Bouchard
authors.forename: Frédéric
authors.initials: F
authors.lastname: Roche
authors.forename: Virginie
authors.initials: V
authors.lastname: Dauphinot
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Deharo
authors.forename: Peggy
authors.initials: P
authors.lastname: Jacon
authors.forename: Dominique
authors.initials: D
authors.lastname: Lamaison
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Bathélemy
authors.forename: Karl
authors.initials: K
authors.lastname: Isaaz
authors.forename: Gabriel
authors.initials: G
authors.lastname: Laurent
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000295:instrumentation; D015716:Electrocardiography, Ambulatory / Q000295:instrumentation*; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D005602:France / Q000453:epidemiology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012008:Recurrence; D013575:Syncope / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology / Q000628:therapy; D013997:Time Factors