I would say how good is Mom’s health overall ? Is your Mom active ,very active . I’m sure the specialist has taken all that into consideration. There are some videos assisted surgeries where surgeons go in with small incisions on your right side rather than opening the chest wall, again a specialized surgeon I had VATS ,video assisted thoracic surgery for a cyst close to the heart . It’s going to be a considerable recovery for for your Mom with all the risks of heart surgery . Just my thoughts Best wishes