The ventricular volume variability study of the Pediatric Heart Network: study design and impact of beat averaging and variable type on the reproducibility of echocardiographic measurements in children with chronic dilated cardiomyopathy.
BACKGROUND
Clinical trials often rely on echocardiographic measures of left ventricular size and function as surrogate end points. However, the quantitative impact of factors that affect the reproducibility of these measures is unknown. To address this issue, the National Heart, Lung, and Blood Institute-funded Pediatric Heart Network designed a longitudinal observational study of children with known or suspected dilated cardiomyopathy aged 0 to 22 years from eight pediatric clinical centers.


METHODS
Clinical data were collected together with 150 echocardiographic indices of left ventricular size and function. Separate observers performed duplicate echocardiographic imaging. Multiple observers performed measurements from three cardiac cycles to enable assessment of intraobserver and interobserver variability. The impacts of beat averaging (BA), observer type (local vs core), and variable type (areas, calculations, dimensions, slopes, time intervals, and velocities) on measurement reproducibility were studied. The outcome measure was percentage error (100 × difference/mean).


RESULTS
Of 173 enrolled subjects, 131 met criteria for dilated cardiomyopathy. BA, variable type and observer type all influenced percentage error (P < .0001). Core interobserver percentage error (medians, 11.4%, 10.2%, and 9.3% for BA using one, two, and three beats, respectively) was approximately twice the intraobserver percentage error (medians, 6.3%, 4.9%, and 4.2% for BA using one, two, and three beats, respectively). Slopes and calculated variables exhibited high percentage error despite BA. Chamber dimensions, areas, velocities, and time intervals exhibited low percentage error.


CONCLUSIONS
This comprehensive evaluation of quantitative echocardiographic methods will provide a valuable resource for the design of future pediatric studies. BA and a single core lab observer improve the reproducibility of echocardiographic measurements in children with dilated cardiomyopathy. Certain measurements are highly reproducible, while others, despite BA, are poorly reproducible.
Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA. colan@alum.mit.edu
Steven D
SD
Colan
Girish
G
Shirali
Renee
R
Margossian
Dianne
D
Gallagher
Karen
K
Altmann
Charles
C
Canter
Shan
S
Chen
Fraser
F
Golding
Elizabeth
E
Radojewski
Michael
M
Camitta
Michael
M
Carboni
Jack
J
Rychik
Mario
M
Stylianou
Lloyd Y
LY
Tani
Elif Seda
ES
Selamet Tierney
Yanli
Y
Wang
Lynn A
LA
Sleeper
D000293:Adolescent; D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D004452:Echocardiography / Q000706:statistics & numerical data*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009929:Organ Size; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D055815:Young Adult