Therefore, due to the lack of knowledge on HF about the relationship of FAP with the most relevant molecules of cardiac fibrosis as well as with the expression of microRNAs involved in the fibrosis process in cardiac tissue, we analyzed its relationship with the main profibrotic genes involved in the fibroblast activation process, such as POSTN or THBS4, and with the main genes involved in the matrix remodeling process, such as COL1A2 or COL3A1. Furthermore, we analyzed the expression of multiple pro- and antifibrotic microRNAs, such as miR-433-3p or miR-9-5p, and their relationship with FAP. Here, FAP is linked to hydrops fetalis.