The diagnostic relevance of NT-proBNP and proANP 31-67 measurements in staging of myxomatous mitral valve disease in dogs.

BACKGROUND: There is no agreement in current publications regarding the reliability of serum concentrations of natriuretic peptides (NPs) to detect dogs with subclinical myxomatous mitral valve disease (MMVD) and to differentiate between asymptomatic stages. OBJECTIVES: We sought to compare N-terminal pro-B-type natriuretic peptide (NT-proBNP) and pro-atrial natriuretic peptide 31-67 (proANP) concentrations between various stages of canine MMVD and to investigate the influence of age, weight, and sex. METHODS: In this prospective study, dogs were classified in different disease stages using the modified Canine Heart failure International Expert Forum (CHIEF) system. Serum NP concentrations were compared between groups. RESULTS: A total of 559 samples from 116 healthy dogs and 236 dogs with MMVD were analyzed. Using cut-off values (1207 pmol/L for NT-proBNP, 1578 fmol/mL for proANP), dogs with MMVD with and without congestive heart failure (CHF) could be differentiated with a sensitivity of 83% for both and specificities of 85% and 86%, respectively. Dogs staged in CHIEF B1 and B2 could not be distinguished based on NP concentrations due to wide variation within the groups. Intact females (means 598 pmol/L and 1036 fmol/mL, respectively) had significantly higher values of both NPs than intact males (315 pmol/L and 836 fmol/mL). CONCLUSIONS: NPs in canine MMVD are useful to discriminate between asymptomatic dogs and dogs with CHF. Due to a large overlap of NP-concentrations between the groups, NPs do not seem to be useful to differentiate between dogs in stages B1 and B2. Interpretation of NT-proBNP and proANP values should include consideration of sex-specific differences.

Lowered N-terminal pro-B-type natriuretic peptide levels in response to treatment predict survival in dogs with symptomatic mitral valve disease.

OBJECTIVES: In humans with congestive heart failure (CHF), better outcome is correlated with lower natriuretic peptide (NP) levels after starting treatment and greater percentage reduction of NP levels. Therefore, the aim of this study was to determine the relationship between absolute and relative changes in N-terminal pro-B-type natriuretic peptide (NT-proBNP) and pro-atrial natriuretic peptide 31-67 (proANP 31-67) and overall cardiac survival in patients with symptomatic myxomatous mitral valve disease (MMVD). Furthermore, we sought to compare clinical and echocardiographic status of 12-month survivors and non-survivors. ANIMALS, MATERIALS AND METHODS: 26 dogs with CHF due to MMVD. Initial NP levels, as well as absolute and percentage changes of follow-up NP levels (between 7 and 30 days after treatment start) and heart failure (HF) class were tested as potential predictors of overall cardiac survivorship. Additionally, various echocardiographic parameters, creatinine concentrations and furosemide doses were compared between 12-month survivors and non-survivors. RESULTS: Dogs with follow-up NT-proBNP level <965 pmol/l had a significantly longer overall cardiac survival than patients with NT-proBNP level >965 pmol/l (P = 0.03). Dogs in a higher HF class had a significantly (P = 0.03) higher probability of shorter survival independent of their NP levels. When dogs were grouped by 12-month survival, only follow-up NT-proBNP levels were significantly different between groups. CONCLUSIONS: HF class at presentation and NT-proBNP levels after initiating treatment are predictive of mortality in patients with symptomatic MMVD. ProANP 31-67 levels, percentage reduction in NPs levels, creatinine or urea concentration, echocardiographic parameters and furosemide dose did not predict outcome.