Diagnostic value of vertebral left atrial size as determined from thoracic radiographs for assessment of left atrial size in dogs with myxomatous mitral valve disease

Abstract

OBJECTIVE To describe vertebral left atrial size (VLAS), a quantitative method to estimate left atrial (LA) size radiographically, and to determine its diagnostic value for prediction of echocardiographic LA enlargement in dogs with myxomatous mitral valve disease (MMVD) of varying severity. DESIGN Prospective observational study. ANIMALS 103 client-owned dogs with a left-sided systolic murmur. PROCEDURES For each dog, 3-view thoracic radiographs were obtained within 24 hours of an echocardiographic examination. The VLAS was measured on right and left lateral thoracic radiographs and compared with the left atrium-to-aortic root ratio acquired from short-axis (LA:AoSx) and long-axis (LA:AoLx) echocardiographic images. Left atrial enlargement was defined as an LA:AoLx ≥ 2.6 or LA:AoSx ≥ 1.6. Dogs were allocated to 4 groups on the basis of MMVD severity. RESULTS Of the 103 dogs, 15, 40, 26, and 22 were assigned to the control (no echocardiographic abnormalities), stage B1 (hemodynamically irrelevant MMVD), B2 (hemodynamically relevant MMVD), and C-D (MMVD with congestive heart failure) groups, respectively. Median VLAS, LA:AoSx, and LA:AoLx for the stage B2 and C-D groups were significantly greater than the corresponding medians for the control and stage B1 groups. There was a moderate positive correlation between VLAS and both LA:AoSx and LA:AoLx. Receiver operating characteristic analyses revealed that a VLAS ≥ 2.3 vertebrae was a useful predictor of LA enlargement. Intraobserver and interobserver agreements for VLAS measurements were high. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated VLAS was a repeatable and useful radiographic measurement for prediction of LA enlargement in dogs with MMVD.

ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs

“…(Class I, LOE: expert opinion) A newer index of radiographic left atrial enlargement, the VLAS, provides a quantitative method of estimating left atrial size. Measured on either the right or left lateral radiograph by drawing a line from the center of the most ventral aspect of the carina to the most caudal aspect of the LA where it intersects with the dorsal border of the caudal vena cava, that line then is transposed to the cranial edge of the 4th thoracic vertebral body . Studies are ongoing to determine a VLAS value that accurately predicts B2 remodeling, but in the absence of echocardiography, VLAS values of ≥3 likely identify Stage B2 MMVD.…”

Radiographic vertebral left atrial size: A reference interval study in healthy adult dogs

“…Differences in VHS according to the canine breed have also been described 4‐11 . However, there are few studies in veterinary medicine aimed at standardizing the radiographic left atrial (LA) size 12‐15 …”

“…A newer index of radiographic LA size, the vertebral left atrial size (VLAS), was recently included in the American College of Veterinary Internal Medicine consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease 17 . One study proposed a cutoff of VLAS ≥ 2.3 vertebrae as a radiographic indicator of LA enlargement in dogs, but only 15 normal dogs were included in the study 13 . For the definition of a reference range in the canine population, a larger sample is desirable.…”

Effect of expiratory phase for radiographic detection of left heart enlargement in dogs with mitral regurgitation

“…The vertebral left atrial size (VLAS) was measured by drawing the first line from the center of the most ventral aspect of the carina, the bifurcation of the left and right mainstem bronchi, to the most caudal aspect of the LA where it intersected with the dorsal border of the caudal vena cava. The line length was compared with the vertebral scale from the beginning at the cranial edge of the fourth thoracic vertebra on the lateral view 10 . For the qualitative assessment, LA enlargement was considered to be present when there was an elevation of the carina and dorsal bulging of the LA with loss of the gentle curvature of caudal margin of the cardiac silhouette in the lateral view.…”

“…Based on the clock face analogy, when the LA is enlarged, a focal bulge of the left auricle can be found at the 2‐3 o'clock position. A recent study suggested that the vertebral left atrial size (VLAS) for quantifying the LA enlargement and VLAS has a moderate positive correction with the echocardiographic measurement of LA/Ao in both the long and short axes 10 . VLAS < 2.1 vertebrae has been suggested to be normal.…”