title: Validation of a classification system to grade fractionation in atrial fibrillation and correlation with automated detection systems.
abstract: OBJECTIVE
  We tested application of a grading system describing complex fractionated electrograms (CFE) in atrial fibrillation (AF) and used it to validate automated CFE detection (AUTO).
  
  
  RESULTS
  Ten seconds bipolar electrograms were classified by visual inspection (VI) during ablation of persistent AF and the result compared with offline manual measurement (MM) by a second blinded operator: Grade 1 uninterrupted fractionated activity (defined as segments > or =70 ms) for > or =70% of recording and uninterrupted > or =1 s; Grade 2 interrupted fractionated activity > or =70% of recording; Grade 3 intermittent fractionated activity 30-70%; Grade 4 discrete (<70 ms) complex electrogram (> or =5 direction changes); Grade 5 discrete simple electrograms (< or =4 direction changes); Grade 6 scar. Grade by VI and MM for 100 electrograms agreed in 89%. Five hundred electrograms were graded on Carto and NavX by VI to validate AUTO in (i) detection of CFE (grades 1-4 considered CFE), and (ii) assessing degree of fractionation by correlating grade and score by AUTO (data shown as sensitivity, specificity, r): NavX 'CFE mean' 92%, 91%, 0.56; Carto 'interval confidence level' using factory settings 89%, 62%, -0.72, and other published settings 80%, 74%, -0.65; Carto 'shortest confidence interval' 74%, 70%, 0.43; Carto 'average confidence interval' 86%, 66%, 0.53.
  
  
  CONCLUSIONS
  Grading CFE by VI is accurate and correlates with AUTO.
authors.affiliation: Cardiology Research Department, Barts and The London NHS Trust and QMUL, St Bartholomew's Hospital, First Floor Dominion House, 60 Bartholomew Close, West Smithfield, London, UK.
authors.forename: Ross J
authors.initials: RJ
authors.lastname: Hunter
authors.forename: Ihab
authors.initials: I
authors.lastname: Diab
authors.forename: Glyn
authors.initials: G
authors.lastname: Thomas
authors.forename: Edward
authors.initials: E
authors.lastname: Duncan
authors.forename: Dominic
authors.initials: D
authors.lastname: Abrams
authors.forename: Mehul
authors.initials: M
authors.lastname: Dhinoja
authors.forename: Simon
authors.initials: S
authors.lastname: Sporton
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Earley
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Schilling
mesh_terms: D000465:Algorithms; D001281:Atrial Fibrillation / Q000145:classification* / Q000175:diagnosis*; D018780:Body Surface Potential Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic