title: Correlation of left atrial diameter by echocardiography and left atrial volume by computed tomography.
abstract: BACKGROUND
  For patients undergoing catheter ablation of atrial fibrillation (AF), left atrial size is a predictor of recurrence of AF during follow-up. For this reason, major clinical trials have used a left atrial diameter (LAD) of more than 5.0 or 5.5 cm, assessed by echocardiography, as an exclusion criterion for patients deemed candidates for ablation of AF. However, whether LAD accurately reflects true left atrial size has not been systematically investigated. Therefore, the purpose of this study was to test the hypothesis that LAD, measured by echocardiography, accurately correlates to left atrial volume measured by computed tomography (CT).
  
  
  RESULTS
  We included 50 patients (mean age 56 +/- 12 years, five female) with symptomatic AF (40% paroxysmal, 60% persistent), referred for catheter ablation. In each patient, transthoracic echocardiography was performed. Additionally, all patients underwent CT using a 64-slice CT scanner. Left atrial volume was calculated by manually tracing left atrial area on each CT cross-sectional image. Patients had a mean LAD measured by echocardiography of 4.5 +/- 0.7 cm, ranging from 2.9 to 5.7 cm. Left atrial volume measured by CT ranged from 67 mL to 270 mL with a mean value of 146 +/- 49 mL. A poor correlation was noted between LAD and left atrial volume, r = 0.49 (P < 0.001).
  
  
  CONCLUSIONS
  LAD measured by echocardiography correlates poorly with left atrial volume measured by CT in patients with AF. As a result, selecting patients with AF for treatment with catheter ablation should not be based on an echocardiographic-derived LAD alone.
authors.affiliation: Division of Heart and Lungs, Department of Cardiology, University Medical Center, Utrecht, The Netherlands.
authors.forename: Irene
authors.initials: I
authors.lastname: Hof
authors.forename: Armin
authors.initials: A
authors.lastname: Arbab-Zadeh
authors.forename: Daniel
authors.initials: D
authors.lastname: Scherr
authors.forename: Karuna
authors.initials: K
authors.lastname: Chilukuri
authors.forename: Darshan
authors.initials: D
authors.lastname: Dalal
authors.forename: Theodore
authors.initials: T
authors.lastname: Abraham
authors.forename: Joao
authors.initials: J
authors.lastname: Lima
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
mesh_terms: D000368:Aged; D004452:Echocardiography; D005260:Female; D006321:Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006325:Heart Atria / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed