Prognostic value of circulating cardiac and renal biomarkers in dogs with myxomatous mitral valve disease

Prognostic evaluation of canine myxomatous mitral valve disease (MMVD) using circulating biomarkers has been attempted, but comprehensive studies are still limited. The present study aimed to investigate the prognostic value of circulating cardiac and renal biomarkers and imaging data in 37 small-breed dogs with MMVD using retrospective data obtained from 2018 to 2022. The circulating cardiac biomarkers included N-terminal probrain natriuretic peptide (NT-proBNP), atrial natriuretic peptide (ANP), and troponin I. The renal biomarkers included blood urea nitrogen (BUN), creatinine, symmetric dimethylarginine, and cystatin C (Cys-C). The imaging data included vertebral heart score, vertebral left atrial size (VLAS), left-atrial-to-aortic ratio, and left ventricle internal diameter in diastole normalized to bodyweight (LVIDDN) from the medical records. The dogs were categorized into high and low groups based on the cutoff values obtained from the receiver-operating characteristic curves. Kaplan-Meier survival curves were generated, and 1-year MMVD-specific survival rates were compared using the restricted mean survival time (RMST) method. The dogs with high VLAS, LVIDDN, and NT-proBNP, ANP, troponin I, BUN, creatinine, or Cys-C levels had significantly shorter MMVD-specific survival times (p < 0.01). NT-proBNP had the largest RMST difference of 187.0 days (95 % confidence interval [CI]: 104.7-269.3 days), followed by Cys-C with 169.3 days (95 % CI: 98.2-240.5 days). Our study findings highlight the potential of NT-proBNP and Cys-C as key prognostic markers in dogs with MMVD. Incorporating the measurements of blood circulating biomarkers may enhance the accuracy of prognostic prediction in dogs with MMVD.