Comparison of NT-pro-BNP Concentration in Cats with Acute Dyspnea From Cardiac or Respiratory Disease
Biomarkers are increasingly used to help differentiate causes of acute dyspnea. We aimed to determine whether NTproBNP blood concentrations clinically differentiated respiratory vs cardiac causes of acute dyspnea in cats.
Recruitment required presentation for acute dyspnea. Each cat was evaluated by medical history, physical examination, thoracic radiography, and echocardiography by a board certified cardiologist. Cause of dyspnea was designated cardiac (CHF) or non-cardiac (primary respiratory disease). A central laboratory blinded to diagnosis performed serum NTproBNP assays. NTproBNP concentrations were compared by Mann Whitney test. Spearman correlation assessed NTproBNP concentrations vs echocardiographic measurements in CHF cats. Receiver operating characteristic analysis evaluated NTproBNP outcome.
Median NTproBNP was significantly different between cats with dyspnea associated with CHF (n=34) vs respiratory disease (n=22) (P<0.0001). Median NTproBNP [interquartile range] was 846 pmol/L [567-1160 pmol/L] for CHF and 52 pmol/L [24-119 pmol/L] for respiratory disease. Correlations (BNP vs echo) were LVPWd (P=0.039, r=0.354), LVd (P=0.113), LVs (P=0.053), %FS (P=073), IVSd (P=0.336), LA (P=0.099), LA/Ao (P=0.12), and vertebral heart score (P=0.995).
NTproBNP >180 pmol/L for dyspnea caused by CHF possessed 94.1% sensitivity, 86.4% specificity, 91.4% positive predictive value, and 90.5% negative predictive value vs respiratory (fitted ROC area under curve, 0.976 [SE=0.0183]). Thus, NTproBNP determination may help differentiate cardiac vs. primary respiratory cause of dyspnea in cats.