I'm sure there are all manners of HCM…I am 81 and have only been on medication for it for 3 or 4 years. The muscle of my heart has enlarged as I understand it so that it is restricting the blood flow. The medication helps this. The doctor said I was born with this and nothing I could have done to prevent it. Your sons case may be different. It is good to find out as much as you can. It is my understanding that usually it can be managed. Hope this helps a little.