title: Optimal Analysis of Left Atrial Strain by Speckle Tracking Echocardiography: P-wave versus R-wave Trigger.
abstract: BACKGROUND
  Left atrial (LA) strain analysis using speckle tracking echocardiography is useful for assessing LA function. However, there is no established procedure for this method. Most investigators have determined the electrocardiographic R-wave peak as the starting point for LA strain analysis. To test our hypothesis that P-wave onset should be used as the starting point, we measured LA strain using 2 different starting points and compared the strain values with the corresponding LA volume indices obtained by three-dimensional (3D) echocardiography.
  
  
  METHODS
  We enrolled 78 subjects (61 ± 17 years, 25 males) with and without various cardiac diseases in this study and assessed global longitudinal LA strain by two-dimensional speckle tracking strain echocardiography using EchoPac software. We used either R-wave peak or P-wave onset as the starting point for determining LA strains during the reservoir (Rres, Pres), conduit (Rcon, Pcon), and booster pump (Rpump, Ppump) phases. We determined the maximum, minimum, and preatrial contraction LA volumes, and calculated the LA total, passive, and active emptying fractions using 3D echocardiography.
  
  
  RESULTS
  The correlation between Pres and LA total emptying fraction was better than the correlation between Rres and LA total emptying fraction (r = 0.458 vs. 0.308, P = 0.026). Pcon and Ppump exhibited better correlation with the corresponding 3D echocardiographic parameters than Rcon (r = 0.560 vs. 0.479, P = 0.133) and Rpump (r = 0.577 vs. 0.345, P = 0.003), respectively.
  
  
  CONCLUSIONS
  LA strain in any phase should be analyzed using P-wave onset as the starting point rather than R-wave peak.
authors.affiliation: Ultrasound Examination Center, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: Department of Cardiovascular Medicine, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Cardiovascular Medicine, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Bando
authors.affiliation: Department of Cardiovascular Medicine, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Saijo
authors.affiliation: Ultrasound Examination Center, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Nishio
authors.affiliation: Ultrasound Examination Center, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Yukina
authors.initials: Y
authors.lastname: Hirata
authors.affiliation: Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Allan L
authors.initials: AL
authors.lastname: Klein
authors.affiliation: Department of Cardiovascular Medicine, Tokushima University Hospital, Tokushima, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Sata
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods; D005260:Female; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology*
keywords: left atrium; strain; three-dimensional echocardiography; two-dimensional speckle tracking echocardiography