NT-pro-BNP Concentration in Preclinical (ISACHC 1a & 1b) Chronic Degenerative Atrioventricular Valve Disease
The Michael E. DeBakey Institute, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University
College Station, TX, USA
Congestive heart failure (CHF, ISACHC Class 2 & 3) can be difficult to diagnose in dogs with long standing preclinical (ISACHC Class 1A or 1B) chronic degenerative atrioventricular valve disease (CVD). NT-proBNP serum concentrations (pmol/L) are elevated in CHF due to CVD and may help confirm that diagnosis if accurate discriminatory cutoffs are established. Many small veterinary reports have described the utility of NT-proBNP for discriminating between dyspnea due to a primary respiratory disease versus CHF. It is more difficult, yet clinically relevant, to determine cutoffs that accurately differentiate dogs with CHF due to CVD from those with preclinical CVD and concurrent respiratory disease. Tarnow et. al. 2007 reported that mean NT-proBNP in Cavalier King Charles Spaniels (CKCS) with ISACHC 1A & 1B 257 ± 92 (mean ± 1SD) was similar to healthy control dogs (259 ± 123) and significantly less than CKCS with CHF due to CVD (1474 ± 646). They concluded that NT-proBNP is not significantly elevated in CKCS with preclinical CVD. These findings coupled with other reported cutoffs in the range of 300-500 pmol/L could lead to the over diagnosis of CHF in dogs with preclinical CVD.
This study reports the NT-proBNP median and range in dogs with various degrees of cardiac remodeling due to preclinical CVD and the correlation between NT-proBNP and various echocardiographic and radiographic indices of cardiac remodeling and Doppler derived E:Ea as an index of cardiac filling pressures. 18 dogs with preclinical CVD were evaluated a total of 24 times. 15 of the 18 dogs were CKCS, mean age was 8.2 ± 2.8 years, and 60% were male. NT-proBNP concentrations were not normally distributed. The median NT-proBNP was 508 with an interquartile range of 323-793, a minimum of 200, and maximum of 2255. Dogs with an increased LVIDd and/or LVIDs (7/24) had significantly elevated NT-proBNP when compared to those whose LVIDd and LVIDs were normal, with a median NTproBNP of 1247 (interquartile range 503-1861) and 371 (interquartile range 279-626) respectively. There was a significant correlation between NT-proBNP and 2D derived La:Ao ratio. There was no significant correlation between NT-pro BNP and VHS, M-mode derived La:Ao ratio, LVIDd and LVIDs (indexed to body surface area), or Doppler derived E:Ea ratio.
NT-proBNP is elevated to various degrees in preclinical CVD and is not correlated to many common indices of cardiac remodeling. Its true utility may lie in its correlation to important clinical endpoints such as onset of congestive heart failure. Larger prospective studies are warranted to further evaluate the clinical utility of this novel test.