Normal Ranges of Left Atrial Strain by Speckle-Tracking Echocardiography: A Systematic Review and Meta-Analysis.
Recent advances in the assessment of myocardial function have facilitated the direct measurement of atrial function using speckle-tracking echocardiography. Currently, normal reference ranges for atrial function using speckle-tracking echocardiography are based on a few initial studies, with variations among modestly sized (n = 100-350) studies.



The authors searched the PubMed, Embase, and Scopus databases for the key terms "left atrial/atrial/atrium" and "strain/function/deformation/stiffness" and "speckle tracking/Velocity Vector Imaging/edge tracking." Studies of global left atrial function using speckle-tracking were selected if they involved >30 normal or healthy participants without any cardiac risk factors. Normal ranges for reservoir strain, conduit strain, and contractile strain were computed using a random-effects model. Meta-regression and subgroup analysis was performed to explore between-study heterogeneity.



Forty studies (2,542 healthy subjects) satisfied the inclusion criteria. Meta-analysis revealed a normal reference range for reservoir strain of 39% (95% CI, 38%-41%, from 40 articles), for conduit strain of 23% (95% CI, 21%-25%, from 14 articles), and for contractile strain of 17% (95% CI, 16%-19%, from 18 articles). Meta-regression identified heart rate (P = .02) and body surface area (P = .003) as contributors to this heterogeneity. Subgroup analyses revealed heterogeneity due to sample size (n > 100 vs N < 100, P = .02).



The normal reference ranges for the three components of left atrial function are demonstrated. The between-study heterogeneity is explained partly by heart rate, body surface area, and sample size.
Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.
Faraz
F
Pathan
Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.
Nicholas
N
D'Elia
Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.
Mark T
MT
Nolan
Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia; Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
Thomas H
TH
Marwick
Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia. Electronic address: kazuaki.negishi@utas.edu.au.
Kazuaki
K
Negishi
D000328:Adult; D016275:Atrial Function / Q000502:physiology*; D004452:Echocardiography / Q000592:standards* / Q000706:statistics & numerical data*; D055119:Elastic Modulus / Q000502:physiology; D054459:Elasticity Imaging Techniques / Q000592:standards* / Q000706:statistics & numerical data*; D019317:Evidence-Based Medicine; D006325:Heart Atria / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength / Q000502:physiology; D013314:Stress, Mechanical; D013718:Tensile Strength / Q000502:physiology
Atrial; Meta-analysis; Normal range; Strain