Are the symptoms of congenital heart disease bad?

It depends on defect: It depends on what kind of defect it is. Some defects have no symptoms, some have mild symptoms such as faster breathing, difficulty eating, increased sweating while feeding. And some defects are life threatening causing low oxygen levels in your body and without surgery or other type of intervention within hours of delivery may be lethal.

Congenital heart : Not always , it varies from no symptoms to reason for dying with significant symptoms in first days of life, depends on type of defect