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

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 LHE 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 LHE , and clinically relevant cutpoints for these radiographic measurements were selected.

RESULTS

The ability of VHS and VHS + VLAS to predict LHE was moderate (area under the curve [AUC] = 0.851; 95% CI, 0.762-0.941; AUC = 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 LHE . A cutpoint of >11.7 had sensitivity = 32.4% (17.4%-50.5%) and specificity = 97.2% (85.5%-99.9%) for predicting LHE . 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 LHE and VHS ≤ 10.8 excluded dogs with LHE . A large percentage of dogs had VHS values intermediate to these cutpoints.