Diagnostic accuracy of right pulmonary vein to right 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 ratio (RPV/RPA), 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 ACVIM stage of MMVD were prospectively enrolled. Left atrium was assessed using the left-atrial-to-aortic ratio (LA:Ao). RPV/RPA were measured at their maximum and minimum diameter (RPVMAX/RPAMAX and RPVMIN/RPAMIN), at the QRS (RPVQRS/RPAQRS) and at the end of the T wave (RPVT/RPAT). RPV and RPA measurements were indexed to the Ao (RPVQRS/Ao, RPVT/Ao, RPVMAX/Ao, RPVMIN/Ao, RPAQRS/Ao, RPAT/Ao, RPAMAX/Ao, RPAMIN/Ao).
Results
The study included 58 dogs in ACVIM stage B1, 38 in stage B2 and 59 in stage C. The RPVT/RPAT and RPVMAX/RPAMAX indexes 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 RPVT/Ao >1.07 presented the highest accuracy in identifying stage C dogs (AUC 0.79, sensitivity of 83.1% and specificity of 71.1%).
Study Limitation
s: Potential misclassification of pulmonary hypertension and post-treatment evaluation can have introduced measurement bias affecting diagnostic accuracy.
Conclusions
The RPV/RPA presented a low diagnostic accuracy in detecting stage C MMVD dogs, but RPVT/Ao, presented a higher diagnostic accuracy in identifying MMVD dogs in stage C, which, was not superior to LA:Ao.