title: The QT Interval as a Noninvasive Marker of Atrial Refractoriness.
abstract: BACKGROUND
  Atrial refractoriness may be an important determinant of atrial fibrillation (AF) risk, but its measurement is not clinically accessible. Because the QT interval predicts incident AF and the atrium and ventricle share repolarizing ion currents, we investigated the association between an individual's QT interval and atrial effective refractory period (AERP).
  
  
  METHODS
  In paroxysmal AF patients presenting for catheter ablation, the QT interval was measured from the surface 12-lead electrocardiogram. The AERP was defined as the longest S1-S2 coupling interval without atrial capture using a 600-ms drive cycle length.
  
  
  RESULTS
  In 28 patients, there was a positive correlation between QTc and mean AERP. After multivariate adjustment, a 1-ms increase in QTc predicted a 0.70-ms increase in AERP.
  
  
  CONCLUSIONS
  The QTc interval reflects the AERP, suggesting that the QTc interval may be used as a marker of atrial refractoriness relevant to assessing AF risk and mechanism-specific therapeutic strategies.
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Kaylin T
authors.initials: KT
authors.lastname: Nguyen
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Gladstone
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Dukes
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Babak
authors.initials: B
authors.lastname: Nazer
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Nitish
authors.initials: N
authors.lastname: Badhwar
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Vasanth
authors.initials: V
authors.lastname: Vedantham
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Gerstenfeld
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Byron K
authors.initials: BK
authors.lastname: Lee
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Lee
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Zian H
authors.initials: ZH
authors.lastname: Tseng
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Jeffrey E
authors.initials: JE
authors.lastname: Olgin
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Melvin M
authors.initials: MM
authors.lastname: Scheinman
authors.affiliation: Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marcus
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis*; D015415:Biomarkers; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers
keywords: QT interval; atrial fibrillation; refractory period