title: P wave analysis with wavelets identifies hypertensive patients at risk of recurrence of atrial fibrillation: A case-control study and 1year follow-up.
abstract: OBJECTIVE
  Hypertension is a major risk factor for atrial fibrillation (AF); however, reliable non-invasive tools to assess AF risk in hypertensive patients are lacking. We sought to evaluate the efficacy of P wave wavelet analysis in predicting AF risk recurrence in a hypertensive cohort.
  
  
  METHODS
  We studied 37 hypertensive patients who presented with an AF episode for the first time and 37 age- and sex-matched hypertensive controls without AF. P wave duration and energy variables were measured for each subject [i.e. mean and max P wave energy along horizontal (x), coronal (y) and sagittal (z) axes in low, intermediate and high frequency bands]. AF-free survival was assessed over a follow-up of 12.1±0.4months.
  
  
  RESULTS
  P wave duration (Pdurz) and mean P wave energy in the intermediate frequency band across sagittal axis (mean2z) were independently associated with baseline AF status (p=0.008 and p=0.001, respectively). Based on optimal cut-off points, four groups were formed: Pdurz<83.2ms/mean2z<6.2μV(2) (n=23), Pdurz<83.2ms/mean2z≥6.2μV(2) (n=10), Pdurz≥83.2ms/mean2z<6.2μV(2) (n=22) and Pdurz≥83.2ms/mean2z≥6.2μV(2) (n=19). AF-free survival decreased (Log Rank p<0.0001) from low risk (Pdurz<83.2ms/mean2z<6.2μV(2)) to high-risk group (Pdurz≥83.2ms/mean2z≥6.2μV(2)). Patients presenting with longer and higher energy P waves were at 18 times higher AF risk compared to those with neither (OR: 17.6, 95% CI: 3.7-84.3) even after adjustment for age, sex, hypertension duration, left atrial size, beta-blocker, ACEi/ARBs and statin therapy.
  
  
  CONCLUSIONS
  P wave temporal and energy characteristics extracted using wavelet analysis can potentially serve as screening tool to identify hypertensive patients at risk of AF recurrence.
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Dakos
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece; Department of Cardiology, Heart Failure Care Group, Royal Brompton Hospital, London, UK. Electronic address: dkonstantinou@med.auth.gr.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Konstantinou
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Yiannis S
authors.initials: YS
authors.lastname: Chatzizisis
authors.affiliation: Laboratory of Medical Informatics, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: Ioanna
authors.initials: I
authors.lastname: Chouvarda
authors.affiliation: Laboratory of Medical Informatics, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Filos
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: Stylianos
authors.initials: S
authors.lastname: Paraskevaidis
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece; Department of Cardiology, Electrophysiology Unit, Royal Brompton Hospital, London, UK.
authors.forename: Lilian
authors.initials: L
authors.lastname: Mantziari
authors.affiliation: Laboratory of Medical Informatics, Aristotle University Medical School, Thessaloniki, Greece; Institute of Applied Biosciences, Center for Research and Technology Hellas, Thessaloniki, Greece.
authors.forename: Nicos
authors.initials: N
authors.lastname: Maglaveras
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: Haralambos
authors.initials: H
authors.lastname: Karvounis
authors.affiliation: First Department of Cardiology, AHEPA University Hospital, Aristotle University Medical School, Thessaloniki, Greece; Third Department of Cardiology, Hippokration University Hospital, Aristotle University Medical School, Thessaloniki, Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Vassilikos
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000453:epidemiology*; D016022:Case-Control Studies; D015984:Causality; D015897:Comorbidity; D003936:Diagnosis, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data; D018572:Disease-Free Survival; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006115:Greece / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000453:epidemiology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D058067:Wavelet Analysis
keywords: Atrial fibrillation; Hypertension; Orthogonal ECG; P wave wavelet analysis