The present invention belongs to the technical field of medicine, relating in particular to : a fused ring compound as represented by Formula (I) for use as a mineralocorticoid receptor antagonist, a pharmaceutically acceptable salt thereof, and an isomer thereof; a preparation method for these compounds; a pharmaceutical preparation containing these compounds; and an application of these compounds, the pharmaceutically acceptable salt thereof, or the isomers thereof in the preparation of medicants for the treatment and/or prevention of kidney injury, cardiovascular diseases such as hypertension, and/or endocrine disease. The definitions of X, Y 1 , Y 2 , Y 3 , R 1 , R 2a , R 2b , R 3a , R 3b , R 4 , Cy and n are as presented in the description.