title: Long-Term Outcome of Patients with Bifascicular Block and Unexplained Syncope Following Cardiac Pacing.
abstract: BACKGROUND
  According to the ACC/AHA/HRS guidelines, cardiac pacing is reasonable in patients with bifascicular block (BF-B) and syncope when other causes have been excluded. The purpose of this study was to assess the long-term outcome of patients with BF-B and unexplained syncope following cardiac pacing.
  
  
  RESULTS
  Between 2009 and 2015, we identified 43 consecutive patients (mean age of 78 ± 12 years, 64% males) who presented with syncope and BF-B and had received a pacemaker (PM). During a mean follow-up period of 31 ± 21 months, syncope recurred in seven patients (16%): 7% (95% standard error [SE] ± 3%) at 1 year and 18% (95% SE ± 7%) at 5 years. At univariable analysis, the only predictor of syncope recurrence was empiric pacing (P = 0.03). There were no syncope recurrences in the 12 patients who received a PM following a positive electrophysiological study (EPS) and the five patients with documentation of paroxysmal atrioventricular block (AVB) during cardiac monitoring (insertable loop recorder [ILR]), (EPS/ILR Group, n = 17) compared to seven of 26 (27%) patients who received empiric pacing (Empiric Group, n = 26; P = 0.02). Progression to high-degree AVB was documented during follow-up in 16 (37%) patients: nine of 17 (53%) patients in the EPS/ILR Group and seven of 26 (27%) patients in the Empiric Group (P = 0.11). There were no injuries reported during ILR monitoring.
  
  
  CONCLUSIONS
  We have shown that syncope recurs not infrequently in patients with BF-B who received pacing for syncope. Nearly one in four patients who had empiric pacing suffered syncope recurrence compared to no recurrences in patients who received a PM following a positive EPS or documentation of transient AVB.
authors: Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors: Matthew M
authors: MM
authors: Kalscheur
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Paolo
authors: P
authors: Donateo
authors: Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors: Kevin E
authors: KE
authors: Wenzke
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Milena
authors: M
authors: Aste
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Daniele
authors: D
authors: Oddone
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Alberto
authors: A
authors: Solano
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Roberto
authors: R
authors: Maggi
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Francesco
authors: F
authors: Croci
authors: Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
authors: Richard L
authors: RL
authors: Page
authors: Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy.
authors: Michele
authors: M
authors: Brignole
authors: Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. mhamdan@medicine.wisc.edu.
authors: Mohamed H
authors: MH
authors: Hamdan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000150:complications / Q000628:therapy*; D006801:Humans; D008297:Male; D012008:Recurrence; D013575:Syncope / Q000628:therapy*; D016896:Treatment Outcome
keywords: EP study; bifascicular block; implantable loop recorder; pacemaker