We first constructed a rat model of heart failure by ligating the left anterior descending branch of the coronary artery, then performed the corresponding experiments at the molecular level of the cAMP/Rap1A signaling pathway to elucidate the mechanism of ONSMP in delaying myocardial fibrosis and provide an idea for the research of new drugs for heart failure treatment. Here, RAP1A is linked to Myocardial fibrosis.