C07 - Biologic Variability of Galectin-3 and NT-proBNP in Healthy Cats and Cats with Occult Hypertrophic Cardiomyopathy

Abstract: Background: The biologic variability (BV) of a biomarker, or change in analyte concentration independent of disease progression, is required for serial monitoring. In cats, this information has not been determined for the cardiac biomarkers N-terminal pro-Brain natriuretic peptide (NT-proBNP) and Galectin-3 (Gal-3).

Hypothesis/Objectives: To determine the BV of Gal-3 and NT-proBNP in healthy and hypertrophic cardiomyopathy (HCM) cats.

Animals: Twelve healthy and 13 occult HCM cats.

Methods: NT-proBNP and Gal-3 were measured using a commercially available assays (IDEXX and RayBiotech). All cats had an examination, echocardiogram, blood pressure, and T4 analysis. Cats were classified as healthy or HCM based on septal or free wall thickness > 6 mm and further staged as B1 (n=8) and B2 (n=5) based on left atrial diameter > 16 mm. Cardiac biomarkers were evaluated within-day, daily, and weekly over 6 weeks.

Results: Within-subject (CV_I) and between-subject (CV_G) coefficients of variation were calculated. For healthy cats: CV_I of 15.9% for Gal-3 and 28.1% for NT-proBNP; CV_G of 33.9% for Gal-3 and 34.9% for NT-proBNP. In healthy cats, a required % change of 47.9% for Gal-3 and 78.9% for NT-proBNP is required to exceed BV.

For HCM: CV_I of 27.9% for Gal-3 and 29.2% for NT-proBNP; CV_G of 67.1% for Gal-3 and 79.7% for NT-proBNP. In all HCM cats, a required % change of 83.9% for Gal-3 and 83.5% for NT-proBNP is required to exceed BV.

Conclusions and clinical importance: The BV of NT-proBNP and Gal-3 in cats should be considered when serially monitoring these cardiac biomarkers.