APJ receptor agonist 4 is a potent and orally active agonist of apelin receptor ( APJ ) with EC 50 and Ki of 0.06 nM and 0.07 nM respectively. APJ receptor agonist 4 displays excellent pharmacokinetic profiles in the rodent heart failure (HF) model. APJ receptor agonist 4 also shows an acceptable safety profile in preclinical toxicology studies. APJ receptor agonist 4 leads to improved cardiac function and can be used for researching the HF disease.