Real-time three-dimensional echocardiography for left atrial volume assessment in Thoroughbred racehorses: observer variability and comparison with two-dimensional echocardiography

Francesca Worsman, Z. Miller, Darren Shaw, Karen Blissitt, John Keen

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Left atrial size predicts cardiac morbidity and mortality in humans and dogs. Real-time three-dimensional echocardiography (3DE) may be reliable for assessing left atrial volume (LAV) in horses.

OBJECTIVES: To determine intra and inter-observer variability estimates of 3DE-LAV and compare it to that of 2DE-LAV estimates.

STUDY DESIGN: Method comparison.

METHODS: 3DE datasets were obtained from 40 horses, then graded for quality, creating a final study population of 22 horses. The 3DE and 2DE maximum LAV (LAVmax ) and minimum LAV (LAVmin ) were measured, and left atrial emptying volume (LA EV) and left atrial ejection fraction (LA EF) calculated, from the same 3D dataset on four occasions using a) a semi-automatic surface recognition algorithm and b) a modified Simpson's method of discs. 3DE LAV measurements were repeated by a second observer.

RESULTS: For 3DE, median LAVmax was 596cm3 for observer one, and 852cm3 for observer two, LAVmin was 373cm3 for observer one and 533cm3 for observer two. Low intra-observer measurement variation was observed for LAVmax and LAVmin , with horse-level intra-class correlation coefficients (ICChorse ) for both observers between 76-85% (horse added as random effect). The inter-observer ICC was 58% for LAVmax and 50% for LAVmin on averaged measurements (with observer added as random effect), indicating consistent differences between observers. While intra-observer variation was similar for 2DE LAVmax measurements, it was greater for LAVmin (ICChorse = 67%). The inter-method ICC for 3DE vs 2DE was low at 14% for LAVmax and ~0% for LAVmin , indicating less-consistent differences with method.

MAIN LIMITATIONS: Small study population, low observer number, use of different imaging modalities (fundamental frequency and octave harmonics).

CONCLUSIONS: 3DE assessment of LAV was reliable, suggesting suitability for longitudinal evaluation of clinical cases. Clinicians should be aware of differences in LAV measurements between observers. More defined measurement guidelines may improve repeatability.
Original languageEnglish
JournalEquine Veterinary Journal
Early online date20 Dec 2020
DOIs
Publication statusE-pub ahead of print - 20 Dec 2020

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