Prognostic relevance of left cardiac enlargement in dogs with preclinical myxomatous mitral valve disease

Determination of radiographic vertebral heart score and vertebral left atrial size cutoffs based on echocardiographic left atrial size in dogs with myxomatous mitral valve disease

Progression of myxomatous mitral valve disease (MMVD) in dogs is a common cause of left atrial enlargement. Recently, a classification of left atrial (LA) size based on echocardiographic measurement has been proposed. This study aims to determine the radiographic LA size by reporting the cutoff values of VHS and VLAS for different groups of echocardiographic-measured LA size in dogs with MMVD. This retrospective analytical cross-sectional study included dogs diagnosed with MMVD grouped based on the echocardiographic LA size into normal (LA/Ao < 1.6), mild (1.6-1.89), moderate (1.9-2.2), and severe enlargement (>2.2) and were compared with ACVIM classification. VHS and VLAS were measured on the right lateral radiograph for each dog and cutoff values were calculated. One hundred and three dogs with MMVD were included in the study. A very strong positive correlation was observed between LA/Ao ratio and VHS (rs , 0.823, P < .01) or VLAS (rs , 0.834, P < .01). For VHS, a cutoff of 10.7 v, 11 v, and 11.5 v were established for echocardiographic LA thresholds of 1.6, 1.9, and 2.2 with a sensitivity of 79%, 92%, and 90% and a specificity of 97%, 90.7%, and 78.1%, respectively. For VLAS, a cutoff of 2.5 v, 2.7 v, and 2.9 v were established for echocardiographic LA cutoffs of 1.6, 1.9, and 2.2 with a sensitivity of 73%, 80%, and 83.3% and a specificity of 94%, 92%, and 86.3%, respectively. The results of this study may facilitate clinical decisions based on radiographic examination in dogs with myxomatous mitral valve disease.

The Thoracic Inlet Length as a Reference Point to Radiographically Assess Cardiac Enlargement in Dogs with Myxomatous Mitral Valve Disease

The diagnostic value of the vertebral heart size (VHS) in dogs with mitral valve degeneration (MVD) is compromised when middle thoracic vertebral anomalies are present. The objective of this study was to assess the use of the thoracic inlet heart score (TIHS) to identify left heart enlargement (LHE) secondary to MVD. The cardiac silhouette of 50 clinically healthy dogs and 106 MVD dogs in different stages was assessed on a right lateral chest radiograph. The TIHS and VHS value were calculated for each patient and compared. The TIHS was significantly different between the control dogs and the dogs with MMVD, increasing with disease stage, control 2.91 ± 0.23, Stage B1 2.98 ± 0.36, B2 3.25 ± 0.34, and C 3.53 ± 0.36, p < 0.05. A THIS ≥3.3 showed 69% sensitivity and 81% specificity to identify LHE. The TIHS showed moderate correlation with the VHS, LA/Ao, and LVIDDN 0.59, 0.42, and 0.62, respectively. The intraobserver and interobserver agreement were almost perfect, 0.96, and substantial, 0.73. The TIHS method can be used to identify LHE secondary to MMVD on dogs' thoracic radiographs.