To investigate the relationship between the Apelin-APJ pathway and HF in humans, here we analyzed a functional variant, rs9943582, in the promoter region of the APLNR gene which encode the APJ receptor in 1,751 CAD patients with different levels of left ventricle systolic function, and evaluated the contribution of the APLNR gene to the genetic susceptibility of left ventricle systolic dysfunction in CAD patients. The gene discussed is APLN; the disease is coronary artery disorder.