BTK and hydrops fetalis: Atrial fibrillation (AF), Bruton’s tyrosine kinase (BTK), bispecific antibodies (BsAbs), chimeric antigen receptor (CAR-T), cytokine release syndrome (CRS), left ventricular ejection fraction (LVEF), Janus kinases (JAK), histone deacetylase (HDAC), monoclonal antibodies (MoAbs), immunomodulatory (IMiDs), heart failure (HF).