Assessment of NTproBNP Concentration in Asymptomatic Cats with Cardiomyopathy
Myocytes express and release natriuretic peptides in response to pressure or volume overload. Diagnosis of cardiomyopathy in asymptomatic cats is challenging and generally requires echocardiographic examination. We aimed to determine whether NTproBNP blood concentrations were elevated in cats with asymptomatic myocardial disease (HCM, DCM, UCM).
Asymptomatic cats with a heart murmur or gallop rhythm were each evaluated by a board certified cardiologist using medical history, physical examination, thoracic radiography, and echocardiography. Healthy cats similarly evaluated and free of cardiovascular disease comprised a control group. A central laboratory blinded to diagnosis performed serum NTproBNP assays. Control vs cardiomyopathy NTproBNP concentrations were compared by Mann Whitney test. Spearman correlation assessed NTproBNP concentrations vs echocardiographic measurements in cardiomyopathy cats. ROC analysis was used to evaluate NTproBNP outcomes.
Median NTproBNP differed between control (n=14) vs cardiomyopathy (n=23) groups (P<0.0001). Median NTproBNP [interquartile range] was 24 pmol/L [24-45.5pmol/L] for control cats and 283pmol/L [154-603pmol/L] for cardiomyopathy cats. Correlations (BNP vs echo) were LVWd (P=0.18), LVd (P=0.497), LVs (P=0.424), %FS (P=0.978), IVSd (P=0.434), LA/Ao (P=0.199) and vertebral heart score (P=0.9).
NTproBNP >70 pmol/L possessed 87.5% sensitivity, 100% specificity, 100% positive predictive value, and 87.5% negative predictive value for asymptomatic cardiomyopathy vs controls (fitted ROC area under curve, 0.982 [SE=0.0193]). Therefore, NTproBNP determination may aid clinical evaluation of asymptomatic cats with myocardial disease.