title: Indices of bipolar complex fractionated atrial electrograms correlate poorly with each other and atrial fibrillation substrate complexity.
abstract: BACKGROUND
  The pathophysiological relevance of complex fractionated atrial electrograms (CFAE) in atrial fibrillation (AF) remains poorly understood.
  
  
  OBJECTIVE
  The aim of this study was to comprehensively investigate how bipolar CFAE correlates with unipolar electrogram fractionation and the underlying electrophysiological substrate of AF.
  
  
  METHODS
  Ten-second unipolar AF electrograms were recorded using a high-density electrode from the left atrium of 20 patients with AF (10 with persistent AF and 10 with paroxysmal AF) undergoing cardiac surgery. Semiautomated bipolar CFAE algorithms: complex fractionated electrogram-mean, interval confidence interval, continuous electrical activity, average complex interval, and shortest complex interval were evaluated against AF substrate complexity measures following fibrillation wave reconstruction derived from local unipolar activation time. The effect of interelectrode spacing and electrode orientation on bipolar CFAE was also examined.
  
  
  RESULTS
  All 5 semiautomated bipolar CFAE algorithms showed poor correlation with each other and AF substrate complexity measures (conduction velocity, number of waves or breakthroughs per AF cycle, and electrical dissociation). Bipolar CFAE also correlated poorly with fractionation index derived from unipolar electrograms. Increased interelectrode spacing resulted in an increase in bipolar CFAE detected except for the interval confidence interval algorithm. CFAE appears unaffected by bipolar electrode orientation (vertical vs horizontal). By contrast, unipolar fractionation index correlated well with AF substrate complexity measures and can be regarded as a marker for conduction block.
  
  
  CONCLUSIONS
  The lack of pathophysiological relevance of bipolar CFAE analysis may in part contribute to the divergent and limited success rates of catheter ablation strategies targeting CFAE.
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands; Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia.
authors.forename: Dennis H
authors.initials: DH
authors.lastname: Lau
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands; Department of Cardiothoracic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Bart
authors.initials: B
authors.lastname: Maesen
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands.
authors.forename: Stef
authors.initials: S
authors.lastname: Zeemering
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands; Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia.
authors.forename: Pawel
authors.initials: P
authors.lastname: Kuklik
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands.
authors.forename: Arne
authors.initials: A
authors.lastname: van Hunnik
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands; Department of Cardiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Theodorus A R
authors.initials: TA
authors.lastname: Lankveld
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands; Department of Cardiothoracic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Elham
authors.initials: E
authors.lastname: Bidar
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Verheule
authors.affiliation: Department of Cardiothoracic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Nijs
authors.affiliation: Department of Cardiothoracic Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Jos
authors.initials: J
authors.lastname: Maessen
authors.affiliation: Department of Cardiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Crijns
authors.affiliation: Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia.
authors.forename: Prashanthan
authors.initials: P
authors.lastname: Sanders
authors.affiliation: Department of Physiology, Maastricht University, Maastricht,The Netherlands. Electronic address: schotten@maastrichtuniversity.nl.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schotten
mesh_terms: D000368:Aged; D000465:Algorithms; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D062906:Cardiac Catheters; D054849:Cardiac Electrophysiology / Q000379:methods; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013223:Statistics as Topic
keywords: Atrial fibrillation; Catheter ablation; Electrogram fractionation; Mapping