Hi, My Mother Is Admitted With Breathing Problems. Doctors Found

Hi, my mother is admitted with Breathing problems. Doctors found her chest x-ray report says she has Bilateral Pleural Effusion, Cardiomegaly, and coarse lung marking seen bilateraly. She is 74 yrs old & doesn't have asthma, sugar, abnormal blood pressure but does have a blockage in her heart. Docs are up to thoracentesis today. Pls advice how serious is this?