Diagnostic accuracy of right pulmonary vein-to-pulmonary artery ratio to identify congestive heart failure in dogs affected by myxomatous mitral valve disease

Introduction/objectives: Right pulmonary vein-to-right pulmonary artery (RPV/RPA) ratio, measured at the end of the T wave, helps identify congestive heart failure in dogs with myxomatous mitral valve disease (MMVD). The aim of this study was to investigate if RPV/RPA, measured at different time points during cardiac cycle, and RPV indexed to the aortic root (Ao) would help to identify MMVD dogs in stage C. Animals, materials and methods: Dogs affected by different stages of MMVD were prospectively enrolled in the present study. The RPV/RPA was measured at their maximum and minimum diameters, at the QRS and at the end of the T wave. The RPV and RPA measurements were indexed to the Ao. Results: The study included 58 dogs in stage B1, 38 in stage B2 and 59 in stage C. The RPV/RPA at the end of the T wave and at the maximum diameter detected dogs in stage C with a sensitivity of 96.6% and 94.9% and a specificity of 36.8% and 39.4%, respectively. The RPV at the end of the T wave-to-Ao ratio >1.07 presented the highest accuracy in identifying stage C dogs (sensitivity of 83.1%, and specificity of 71.1%). Study limitations: Potential misclassification of pulmonary hypertension and post-treatment evaluation could have introduced a measurement bias affecting diagnostic accuracy. Conclusions: The RPV/RPA presented a low diagnostic accuracy in detecting stage C MMVD dogs, but RPV at the end of the T wave-to-Ao ratio, presented a higher diagnostic accuracy, which was not superior to left-atrial-to-aortic ratio.