N-terminal pro-B-type natriuretic peptide (NTproBNP) is a stable molecule that circulates in the blood after being released from heart muscle cells. Amount of NT-proBNP released into the blood is related to heart stretch and correlates to severity of heart disease. Studies in humans with congestive heart failure (CHF) have shown that a decrease in NT-proBNP or lower NT-proBNP concentrations is associated with a more favorable outcome. In addition, other studies in humans have shown better outcomes for heart failure patients when therapy is guided by NT-proBNP measurements.
In this study, Researchers from Cummings School of Veterinary Medicine, Tufts University, MA investigated whether serial measurements of NT-proBNP concentrations can aid in determining survival time after treatment in cats with CHF secondary to cardiomyopathy. Thirty-one cats (27 with hypertrophic cardiomyopathy, HCM, and 4 with dilatory cardiomyopathy, DCM) were included in this study. NT-proBNP measurements were performed at hospital admission, at the time of discharge (e.g., 1-4 days) from the hospital and at re-evaluation 7–10 days later.
The median survival time for the 31 cats from the initial presentation was 109 days (range, 1–709 days), with 5 cats still alive at the time of analysis. Cats with a larger percent decrease in NT-proBNP concentration from admission to discharge had a significantly longer survival time (median survival time = 182 days [range, 2–379 days]) compared to cats with a smaller percent change during hospitalization (median survival time = 60 days [range, 6–709 days]). Cats that did not have signs of active CHF (n = 18) at the time of the 7–10 day re-evaluation had a longer survival time (median = 196 days [range, 11–709 days]) compared to cats with signs of active CHF at the re-evaluation (n = 10, median = 82 days [range, 6–216 days]). Cats whose owners did not have trouble administering medications had a longer survival time compared to cats whose owners had trouble administering medications.
When comparing the change in NT-proBNP concentrations from admission to discharge, cats that received pimobendan (n = 16), a medication that improves heart contraction, had a significantly greater decrease in NT-proBNP concentrations compared to cats that did not receive pimobendan. However, the authors did not draw a conclusion for increased survival time for cats on pimobendan due to the small sample size and the use of multiple medications. Additional research is warranted to assess the relationship between pimobendan, NT-proBNP, and survival in cats with CHF.
The current study was not designed to identify an absolute target number for NT-proBNP concentrations that predict longer survival time but this would be valuable information and should be investigated in future studies. They did, however, observe a significant association between a larger decrease in NT-proBNP concentrations and survival time, which warrants further investigation to further affirm the potential utility of NT-proBNP as an adjunct in the management of cats with CHF. [GO]