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

Abstract

Thoracic radiography is a useful technique for the evaluation of cardiac dimensions, especially when echocardiography is not possible. The vertebral left atrial size (VLAS) has recently been proposed as a new radiographic method for quantifying left atrial dimensions in dogs. The aims of this retrospective, reference interval, observational study were to describe values for VLAS in a group of healthy adult dogs and to compare intraobserver and interobserver agreement for VLAS versus vertebral heart score (VHS) methods. Thoracic radiographs of 80 healthy adult dogs were evaluated. Normal left atrial size was determined based on an echocardiographic left atrial‐to‐aorta ratio < 1.6. The VLAS and vertebral heart score values were measured from right lateral radiographs. The correlations between VLAS, the vertebral heart score, and the left atrial‐to‐aorta ratio were evaluated. The effects of body weight, sex, and age were also tested using regression analyses. The median value of VLAS were 1.9, with a reference interval of 1.4‐2.2. A positive correlation was found between VLAS and vertebral heart score values (r = 0.53; P < .0001). No effect of body weight, sex, and age on VLAS was detected. Excellent intraobserver and interobserver agreements were found for both VLAS and vertebral heart score methods (intraclass correlation coefficients ≥ 0.91). Findings from this sample of healthy dogs indicated that VLAS is a repeatable radiographic method for quantifying left atrial size. Further studies are warranted to evaluate this measure in clinically affected dogs.

Evaluation of radiographic predictors of left heart enlargement in dogs with known or suspected cardiovascular disease

“…A recent study has also shown that VHS is influenced by the cardiac cycle but VLAS is not 36 . Our data suggest that in a dog with suspected cardiovascular disease, if VLAS is increased above normal (ie, >2.3 vertebrae) 19 clinicians can be reasonably confident the LA is enlarged. Conversely, if VHS is increased (using breed‐specific cutoffs or VHS >10.7 18 if mixed‐breed), there is approximately a 40% chance the LA is not enlarged (false negative).…”

“…If unavailable or a mixed‐breed, normal VHS was considered to be ⩽10.7 vertebrae 18 . Normal VLAS was considered to be ⩽2.3 vertebrae 19 …”

“…18 Normal VLAS was considered to be ≤2.3 vertebrae. 19 Radiographic left atrial enlargement (RadLAE The radiologists had access to all projections. Echocardiographic LA size was determined using two different body size-indexed linear measurements of LA size: (a) long-axis left atrial dimension indexed to the long-axis aortic valve annulus diameter (LAD/AoD_Lx) (Figure 2) and (b) short-axis LA indexed to the shortaxis aortic root (LA/Ao_Sx; Figure 3).…”

“…Compared to the more well-known VHS, which offers a global assessment of cardiac size, VLAS is a newer radiographic measurement intended to specifically quantify left atrial (LA) size. Reference intervals for VLAS have recently been published, 19 and a growing body of literature supports the diagnostic utility of VLAS for detecting echocardiographically confirmed left heart enlargement and clinical staging in dogs with MMVD. [2][3][4] A recent study has suggested VHS is more clinically useful compared to VLAS to identify echocardiographic left heart enlargement in dogs with MMVD.…”

A radiographic study of breed‐specific vertebral heart score and vertebral left atrial size in Chihuahuas

“…In addition, most studies reporting breed-specific reference values of the VHS included a maximum of 30 cases per breed. 5,6,[10][11][12]14,26 Finally, similar to previous studies on radiographic vertebral-based measurement, 11,16,27,28 our sample population did not include dogs younger than 12 months. Based on our review of the literature, there are no large studies published that attest whether young age and skeletal immaturity can have a significant influence on vertebral-based measurement.…”