title: The signal-averaged electrocardiogram before and after electrical cardioversion of persistent atrial fibrillation-implications of the sudden change in rhythm.
abstract: BACKGROUND
  Atrial fibrillation (AF), electrical cardioversion (direct current, or DC) shock energy, and a sudden change to sinus rhythm (SR) might all influence the interpretation of the signal-averaged electrocardiogram (SAECG) as risk markers of ventricular tachyarrhythmia.
  
  
  METHODS
  The SAECG was recorded in 82 patients with persistent AF before and 2 hours after DC and analyzed for ventricular late potentials (LPs) and spectral turbulence.
  
  
  RESULTS
  Sixty-nine patients (84%) obtained SR. Their mean (SD) heart rate decreased by 22 (20) beats/min, and the QTcF interval was significantly prolonged, 17 (38) milliseconds, as was the filtered QRS duration, 1.1 (4.7) milliseconds (40 Hz). The proportion of LP positivity (20%) did not change with the change in rhythm. Eight of 60 spectral turbulence-negative patients before DC became positive after DC (P = .01). The change in SAECG variables did not correlate significantly with the amount of energy delivered at DC.
  
  
  CONCLUSIONS
  The LP analysis provided similar results in AF and SR, whereas the spectral turbulence analysis was more abnormal in SR. The electrical shock itself did not seem to explain this phenomenon.
authors.affiliation: Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. christer.gottfridsson@medicine.gu.se
authors.forename: Christer
authors.initials: C
authors.lastname: Gottfridsson
authors.forename: Thomas
authors.initials: T
authors.lastname: Karlsson
authors.forename: Nils
authors.initials: N
authors.lastname: Edvardsson
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000628:therapy*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004554:Electric Countershock; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome