Prenatal Pulmonary Stenosis

I am 20 weeks pregnant and my baby has just been diagnosed with pulmonary stenosis. I have been told by a paediatric cardiologist that the condition is classified as moderate to severe but is more on the severe side and the baby will need treatment birth, either balloon surgery or open heart surgery. There is a chance that the baby will die of heart failure before birth.

We have also been told that the condition can be associated with chromosomal abnormalities and we should do the amniocentesis test which we are not keen to do given the risks associated with it.

Has anyone else been through the same thing and can offer us any advice or further information regarding the survival rate of babies with this kind of heart condition?