Utility of radiographic measurements to predict echocardiographic left heart enlargement in dogs with preclinical myxomatous mitral valve disease

Abstract Background Evaluation of left heart size helps determine disease severity in dogs with myxomatous mitral valve disease (MMVD). Hypothesis/Objectives Determine the ability of radiographic vertebral heart size (VHS) and vertebral left atrial size (VLAS) to predict LHEECHO in dogs with preclinical MMVD. Animals Seventy client‐owned dogs with MMVD and no historical or present clinical or radiographic evidence of congestive heart failure (CHF). Methods Retrospective cross‐sectional study of dogs with same‐day echocardiography and thoracic radiography. Receiver‐operating characteristic (ROC) curves were used to assess the ability of VHS, VLAS, and VHS + VLAS to discern dogs with and without LHEECHO, and clinically relevant cutpoints for these radiographic measurements were selected. Results The ability of VHS and VHS + VLAS to predict LHEECHO was moderate (area under the curve [AUC]VHS = 0.851; 95% CI, 0.762‐0.941; AUCVHS + VLAS = 0.865; 0.783‐0.947), and performance of VLAS and VHS + VLAS was not different from that of VHS alone. A VHS cutpoint of >10.8 had sensitivity = 91.1% (76.3%‐98.1%) and specificity = 69.4% (51.9%‐83.7%) for predicting LHEECHO. A cutpoint of >11.7 had sensitivity = 32.4% (17.4%‐50.5%) and specificity = 97.2% (85.5%‐99.9%) for predicting LHEECHO. Thirty (43%) of the 70 dogs had a VHS value of 10.9 to 11.7. Conclusions and Clinical Importance Vertebral heart size >11.7 identified dogs with LHEECHO and VHS ≤ 10.8 excluded dogs with LHEECHO. A large percentage of dogs had VHS values intermediate to these cutpoints.