NT-pro-BNP Assay Distinguishes Cardiac vs Primary Respiratory Causes of Respiratory Signs in Dogs
M.A. Oyama1; J.E. Rush2; E.A. Rozanski2; P.R. Fox3; C.A. Reynolds1; S. Gordon4; B. Bulmer5;B. Lefbom6; W. Brown7; L. Lehmkuhl8; R. Prosek9; M. Lesser10; M. Kraus11; M. Bossbaly12; G. Rapoport13
1University of Pennsylvania, Philadelphia, PA, USA; 2Tufts University, North Grafton, MA, USA; 3The Animal Medical Center, NY, NY, USA; 4Texas A&M University, College Station, TX, USA; 5Oregon State University, Corvallis, OR, USA; 6Chesapeake Veterinary Cardiology Associates, Vienna, VA, USA; 7Veterinary Cardiology Consultants, Novi, MI, USA; 8MedVet, Worthington, OH, USA; 9University of Florida, Gainsville, FL, USA; 10Advanced Veterinary Care Center, Lawndale, CA, USA; 11Cornell University, Ithaca, NY, USA; 12Heartsound Consultants, Langhorne, PA, USA; 13Angell Memorial Animal Hospital, Boston, MA, USA
In dogs with respiratory signs, differentiation of the underlying etiology (i.e., congestive heart failure (CHF) vs. primary respiratory disease, such as pneumonia, chronic airway disease, fibrosis, etc.) is an important step towards accurate diagnosis and treatment. NT-pro-B-type natriuretic peptide (NT-proBNP) is elevated in dogs with CHF and we sought to evaluate its ability to differentiate cardiac vs. non-cardiac etiology of respiratory signs in a prospective multicenter clinical study. Dogs with respiratory signs (i.e., tachypnea, cough, increased respiratory effort, etc.) that were judged severe enough by the owner to adversely affect the dog's quality of life were recruited from 13 sites. Dogs underwent physical exam, thoracic radiographs, and echocardiogram, after which a board-certified cardiologist categorized etiology of signs as follows: Group 1, CHF; Group 2, primary respiratory disease; Group 3, primary respiratory disease with concurrent heart disease but without CHF; Group 4, equivocal. Serum NT-proBNP assay was performed at a central laboratory blinded to the diagnosis. Complete data was available for 116 dogs. Median NT-proBNP was significantly different between Groups 1 and 2 and between Groups 1 and 3 (P<0.001). Group 1, n=62, median NT-proBNP=2445 pmol/L, [interquartile range=1499-3134]; Group 2, n=21, NT-proBNP=413 pmol/L [245-852]; Group 3, n=28, NT-proBNP=510 pmol/L [353-1212]). NT-proBNP >1200 pmol/L possessed 85.5% sensitivity, 81.6% specificity, 85.5% positive predictive value, and 81.6% negative predictive value for identifying dogs with congestive heart failure (Group 1) vs. dogs with primary respiratory disease with or without concurrent heart disease (Groups 2 and 3). Area under the receiver-operating characteristic curve was 0.908 (SE=0.029).