Evaluation of Plasma N-Terminal Pro-Brain Natriuretic Peptide (NT-proBNP) Concentrations in Dogs with Mitral Valve Insufficiency

The diagnostic significance of the plasma concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP) was evaluated in 72 dogs with mitral valve insufficiency and 36 control dogs. In the controls, the plasma NT-proBNP concentration was 163.9 +/- 114.7 (SD) pmol/l. The values in those with International Small Animal Cardiac Health Council (ISACHC) functional classification of heart failure class Ia, Ib, II and IIIa mitral valve insufficiency were 302.8 +/- 257.1 (n=21), 634.2 +/- 642.5 (n=23), 1,277.9 +/- 756.2 (n=18) and 1,908.9 +/- 538.8 (n=10) pmol/l, respectively; those in the class Ib or severer groups were significantly higher than that in the controls. In dogs in which the intensity of cardiac murmurs was Levine 3, 4, 5 and 6, plasma NT-proBNP concentrations were 647.6 +/- 577.3 (n=27), 1,184.7 +/- 841.0 (n=18), 1,532.4 +/- 784.2 (n=10) and 1,461.8 +/- 932.2 (n=4) pmol/l, respectively, and were significantly higher than that in the controls. The plasma NT-proBNP concentration was significantly correlated with the cardiac size (VHS) and LA/Ao (r=0.611, n=89, p<0.01; and r=0.705, n=91, p<0.01, respectively). When dogs with ISACHC class II or IIIa were regarded as heart failure, the cut-off value was 713.5 pmol/l, and the sensitivity and specificity were 0.913 and 0.857, respectively. These findings could indicate that plasma NT-proBNP concentration was significantly associated with the severity of heart failure due to mitral valve insufficiency in dogs. Further investigation is required to determine factors other than heart failure affecting plasma NT-proBNP concentration.