title: Surface atrial frequency analysis in patients with atrial fibrillation: a tool for evaluating the effects of intervention.
abstract: BACKGROUND
  The aims of this study were to evaluate (1) principal component analysis as a technique for extracting the atrial signal waveform from the standard 12-lead ECG and (2) its ability to distinguish changes in atrial fibrillation (AF) frequency parameters over time and in response to pharmacologic manipulation using drugs with different effects on atrial electrophysiology.
  
  
  RESULTS
  Twenty patients with persistent AF were studied. Continuous 12-lead Holter ECGs were recorded for 60 minutes, first, in the drug-free state. Mean and variability of atrial waveform frequency were measured using an automated computer technique. This extracted the atrial signal by principal component analysis and identified the main frequency component using Fourier analysis. Patients were then allotted sequentially to receive 1 of 4 drugs intravenously (amiodarone, flecainide, sotalol, or metoprolol), and changes induced in mean and variability of atrial waveform frequency measured. Mean and variability of atrial waveform frequency did not differ within patients between the two 30-minute sections of the drug-free state. As hypothesized, significant changes in mean and variability of atrial waveform frequency were detected after manipulation with amiodarone (mean: 5.77 vs 4.86 Hz; variability: 0.55 vs 0.31 Hz), flecainide (mean: 5.33 vs 4.72 Hz; variability: 0.71 vs 0.31 Hz), and sotalol (mean: 5.94 vs 4.90 Hz; variability: 0.73 vs 0.40 Hz) but not with metoprolol (mean: 5.41 vs 5.17 Hz; variability: 0.81 vs 0.82 Hz).
  
  
  CONCLUSIONS
  A technique for continuously analyzing atrial frequency characteristics of AF from the surface ECG has been developed and validated.
authors.affiliation: Department of Academic Cardiology, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Trust, Newcastle upon Tyne, United Kingdom. D.T.Raine@ncl.ac.uk
authors.forename: Dan
authors.initials: D
authors.lastname: Raine
authors.forename: Philip
authors.initials: P
authors.lastname: Langley
authors.forename: Alan
authors.initials: A
authors.lastname: Murray
authors.forename: Asunga
authors.initials: A
authors.lastname: Dunuwille
authors.forename: John P
authors.initials: JP
authors.lastname: Bourke
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology; D018780:Body Surface Potential Mapping / Q000295:instrumentation*; D002908:Chronic Disease; D015716:Electrocardiography, Ambulatory; D004594:Electrophysiology; D006325:Heart Atria / Q000503:physiopathology*; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D012008:Recurrence