title: Differences in the morphology and duration between premature P waves and the preceding sinus complexes in patients with a history of paroxysmal atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Experimental and human mapping studies have demonstrated that perpetuation of AF is due to the presence of multiple reentrant wavelets with various sizes in the right and left atria.
  
  
  OBJECTIVE
  Atrial fibrillation may be induced by atrial ectopic beats originating in the pulmonary veins, and premature P-wave (PPW) patterns may help to identify the source of firing.
  
  
  METHODS
  To evaluate the morphology and duration of PPWs, 12-lead digital electrocardiogram (ECG) strips containing clearly definable PPWs not merging with the preceding T waves were obtained in 25 patients with AF history (9 men, mean age 59.5 +/- 2.2 years) and 25 subjects without any previous AF history (11 men, mean age 53.6 +/- 25 years). The polarity of PPWs was evaluated in all 12 ECG leads. Previously described indices, such as P maximum, P dispersion (= P maximum-P minimum), P mean, and P standard deviation were also calculated.
  
  
  RESULTS
  Premature P-wave patterns were characterized by more positive P waves in lead V1. All P-wave analysis indices were significantly higher in patients with AF than in controls when calculated in the sinus beat, whereas they did not differ between the two groups when calculated in the PPW. P-wave indices did not differ between the PPW and the sinus either patients with AF or controls, except for P mean, which was significantly higher in the sinus (110.1 +/- 1.7 ms) than in the PPW (100 +/- 2 ms) only in patients with AF (p = 0.001).
  
  
  CONCLUSIONS
  The evaluation of PPW patterns is only feasible in a small percentage of short-lasting digital 12-lead ECG recordings containing ectopic atrial beats. Premature P wave patterns characterized by more positive P waves in lead V1, which indicates a left atrial origin in the ectopic foci. The observed differences in P-wave analysis indices between patients with AF and controls and between sinus beats and PPWs may be attributed to the presence of electrophysiologic changes in the atrial substrate.
authors.affiliation: Department of Cardiology, Pammakaristos Hospital, Athens, Greece. hrodil@yahoo.com
authors.forename: Polychronis E
authors.initials: PE
authors.lastname: Dilaveris
authors.forename: Antonios
authors.initials: A
authors.lastname: Pantazis
authors.forename: George
authors.initials: G
authors.lastname: Zervopoulos
authors.forename: John
authors.initials: J
authors.lastname: Kallikazaros
authors.forename: Christodoulos
authors.initials: C
authors.lastname: Stefanadis
authors.forename: Pavlos K
authors.initials: PK
authors.lastname: Toutouzas
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged