title: Prolonged P wave duration in adults with secundum atrial septal defect: a marker of delayed conduction rather than increased atrial size?
abstract: OBJECTIVE
  Although atrial fibrillation is a frequent complication of an atrial septal defect (ASD) of the secundum type, the underlying mechanisms are poorly understood. Atrial conduction disturbances, manifested as a prolonged P-wave duration, have been suggested as a substrate for arrhythmia. Prolongation of the P-wave in unrepaired ASD has been demonstrated by means of the conventional ECG, but not by more sophisticated methods. The aim of the study was to analyse P-wave duration and morphology by high-resolution P-wave signal-averaged ECG (PSA-ECG) and to investigate potential atrial mechano-electrical interactions in adults with an unrepaired ASD.
  
  
  RESULTS
  P-wave signal-averaged-ECG was obtained in 35 adult patients (age 53 +/- 15 years) with ASD and compared with an equal number of sex- and age-matched healthy controls. Right and left atrial sizes were assessed by echocardiography in the ASD group. P wave duration was significantly longer in the ASD group than in control subjects (148 +/- 16 vs. 128 +/- 15 ms, P < 0.0001). P-wave morphology did not differ significantly between patients and controls. There was no clear relation between P-wave duration and atrial size.
  
  
  CONCLUSIONS
  Atrial septal defect in the adult is characterized by a prolonged P-wave duration, indicating delayed atrial conduction, which is not related to the enlargement of the atria but rather to conduction delay. The nature and potential reversibility of this warrant further investigation.
authors.affiliation: Department of Cardiology, Lund University Hospital, SE-221 85 LUND, Sweden. ulf.thilen@skane.se
authors.forename: Ulf
authors.initials: U
authors.lastname: Thilén
authors.forename: Jonas
authors.initials: J
authors.lastname: Carlson
authors.forename: Pyotr G
authors.initials: PG
authors.lastname: Platonov
authors.forename: Rasmus
authors.initials: R
authors.lastname: Havmöller
authors.forename: S Bertil
authors.initials: SB
authors.lastname: Olsson
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006344:Heart Septal Defects, Atrial / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted