APLN and heart failure: For instance, apelin mRNA levels in the left ventricles were increased approximately 4.7- and 3.3-fold in coronary heart disease-induced and idiopathic dilated cardiomyopathy-induced chronic heart failure, respectively, whereas APLNR mRNA was downregulated in the left ventricle of coronary heart disease-induced heart failure (Földes et al., 2003).