The cardiac sodium-calcium exchanger gene (NCX-1) is a potential canine cardiac biomarker of chronic mitral valvular insufficiency

Background: The cardiac sodium-calcium exchanger gene (NCX-1) is upregulated in humans and mice with congestive heart failure (CHF). Hypothesis: NCX-1 expression is upregulated in dogs with heart failure from chronic mitral valvular insufficiency (CMVI). Animals: Client-owned 14 healthy control dogs and 30 dogs with CMVI. Methods: Prospective, controlled, observational study. We investigated the levels of NCX-1 expression in dogs at different stages of CMVI with real-time reverse transcription polymerase chain reaction. Results: The mRNA expression levels of NCX-1 were determined in peripheral blood samples obtained from the animals used in this study. Dogs were graded by the severity of disease. The fold differences in the levels of mRNA expression compared with controls were 1.39 ± 0.88 (group I), 1.32 ± 0.65 (group II), 4.86 ± 1.25 (group III), and 5.96 ± 1.69 (group IV). NCX-1 expression was significantly higher in groups III and IV (Po.05) compared with the healthy controls, whereas groups I and II were not. Conclusions and Clinical Importance: The level of NCX-1 expression was significantly higher in groups of dogs with moderate to severe CMVI (groups III and IV) compared with the controls. Our findings indicate that NCX-1 can be a biomarker for chronic valvular disease in dogs and is a potential biomarker for severity of heart disease.