title: Principal component analysis of atrial fibrillation: inclusion of posterior ECG leads does not improve correlation with left atrial activity.
abstract: BACKGROUND
  Lead V1 is routinely analysed due to its large amplitude AF waveform. V1 correlates strongly with right atrial activity but only moderately with left atrial activity. Posterior lead V9 correlates strongest with left atrial activity.
  
  
  OBJECTIVE
  (1) To establish whether surface dominant AF frequency (DAF) calculated using principal component analysis (PCA) of a modified 12-lead ECG (including posterior leads) has a stronger correlation with left atrial activity compared to the standard ECG. (2) To assess the contribution of individual ECG leads to the AF principal component in both ECG configurations.
  
  
  METHODS
  Patients were assigned to modified or standard ECG groups. In the modified ECG, posterior leads V8 and V9 replaced V4 and V6. AF waveform was extracted from one-minute surface ECG recordings using PCA. Surface DAF was correlated with intracardiac DAF from the high right atrium (HRA), coronary sinus (CS) and pulmonary veins (PVs).
  
  
  RESULTS
  96 patients were studied. Surface DAF from the modified ECG did not have a stronger correlation with left atrial activity compared to the standard ECG. Both ECG configurations correlated strongly with HRA, CS and right PVs but only moderately with left PVs. V1 contributed most to the AF principal component in both ECG configurations.
authors.affiliation: Department of Cardiology, Freeman Hospital, Newcastle Upon Tyne, UK. Electronic address: daniel.raine@nhs.net.
authors.forename: Daniel
authors.initials: D
authors.lastname: Raine
authors.affiliation: School of Engineering, University of Hull, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Langley
authors.affiliation: Department of Cardiology, Freeman Hospital, Newcastle Upon Tyne, UK.
authors.forename: Ewen
authors.initials: E
authors.lastname: Shepherd
authors.affiliation: Department of Cardiology, Freeman Hospital, Newcastle Upon Tyne, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Lord
authors.affiliation: Department of Cardiology, Freeman Hospital, Newcastle Upon Tyne, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Murray
authors.affiliation: Institute of Cellular Medicine, Newcastle University, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Murray
authors.affiliation: Department of Cardiology, Freeman Hospital, Newcastle Upon Tyne, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Bourke
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005583:Fourier Analysis; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D025341:Principal Component Analysis; D012015:Reference Standards; D012815:Signal Processing, Computer-Assisted
keywords: Atrial fibrillation; Dominant frequency; Principal component analysis; QRST subtraction; Surface electrocardiogram