title: Evolution of P-wave morphology in healthy individuals: a 3-year follow-up study.
abstract: BACKGROUND
  Orthogonal P-wave morphology in healthy men and women has been described using unfiltered signal-averaged technique and holds information on interatrial conduction. The stability of P-wave morphology in healthy subjects over time is not fully known.
  
  
  METHODS
  Sixty-seven healthy volunteers were investigated (29 males, aged 63 +/- 14 years, 48 females, 60 +/- 13 years). Orthogonal lead data (X, Y, and Z) were derived from standard 12-lead ECGs (recording length 6 minutes, sampling rate 1kHz, resolution 0.625 muV) recorded at baseline (BL), and 3 years later at follow-up (FU). P waves were then signal-averaged and analyzed regarding P-wave morphology, locations of maxima, minima, zero-crossings, and P-wave duration (PWD).
  
  
  RESULTS
  No differences of P-wave variables were observed at FU compared to BL, including PWD (127 +/- 12 vs 125 +/- 14 ms at BL and FU, respectively, n.s.). In 59 of the 67 subjects (88%), the P-wave morphology was unaltered at FU. However, in the remaining eight cases a distinctively different morphology was observed. The most common change (P=0.030) was from negative polarity to biphasic (-/+) in Lead Z (n=5). In one case the opposite change was observed and in two cases transition into advanced interatrial block morphology was evident at FU.
  
  
  CONCLUSIONS
  In the majority of healthy subjects, P-wave morphology is stable at 3-year FU. Subtle morphological changes, observed principally in Lead Z, suggest variation of interatrial conduction. These changes could not be detected by measuring conventional PWD that remained unchanged in the total population.
authors.affiliation: Department of Cardiology, Lund University, Lund, Sweden. Rasmus.Havmoller@med.lu.se
authors.forename: Rasmus
authors.initials: R
authors.lastname: Havmöller
authors.forename: Jonas
authors.initials: J
authors.lastname: Carlson
authors.forename: Fredrik
authors.initials: F
authors.lastname: Holmqvist
authors.forename: Bertil
authors.initials: B
authors.lastname: Olsson
authors.forename: Pyotr
authors.initials: P
authors.lastname: Platonov
mesh_terms: D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012984:Software; D018709:Statistics, Nonparametric