(C36) Investigations of Asymmetric Dimethyl Arginine (ADMA) as a Biomarker in Preclinical Myxomatous Mitral Valve Disease

Abstract: Background- Asymmetric dimethyl arginine (ADMA) is a biomarker of endothelial dysfunction. Increased circulating ADMA has been demonstrated in dogs with congestive heart failure secondary to myxomatous mitral valve disease (MMVD). We hypothesise that endothelial dysfunction, and therefore plasma ADMA, is greater in dogs with stage B2 (preclinical MMVD with cardiomegaly) vs stage B1 (preclinical MMVD without cardiomegaly). Objectives- To compare plasma ADMA measurements between dogs with stage B1 vs B2 MMVD.Animals- 42 dogs of a variety of breeds examined between March 2020 and August 2023 (16/42 B, 26/42 B2). Methods- Prospective, cross-sectional study. All dogs underwent history, physical examination, blood pressure measurement, electrocardiography, echocardiography and blood sampling for diagnostic testing. Surplus plasma was stored at -80°C for batched measurement of ADMA using a commercially-available competitive ELISA. Between groups comparisons were made using Mann Whitney-U tests. Receiver operator characteristic (ROC) curve analysis was used to test the performance of plasma ADMA in differentiating stage B1 from stage B2. Results- Plasma ADMA measurements were significantly higher in dogs with stage B2 (median=24.26ng/mL [minimum=19.44, maximum=57.88]) vs stage B1 MMVD (19.31ng/mL [13.94- 22.56]) MMVD (P <0.0001). Conclusions and clinical importance- Dogs with preclinical MMVD and plasma ADMA >21.41ng/mL are more likely to be in stage B2; this might be useful in primary practice to help prioritise dogs for echocardiographic assessment.