Hi there @joannoxenham, let me officially welcome you to Mayo Connect.
I posted an article from Mayo Clinic that you may find interesting if you have not read it already. I would 100% encourage you to seek a second opinion and find an expert in HOCM. I had severe HOCM as well and had two additional opinions outside of my small town cardiologist. He had misdiagnosed me with four or five different things until I finally got to Cedars-Saini. I next went to Mayo Rochester and was further diagnosed with severe HOCM and told I needed a septal myectomy. I think all the blood drained from my head, my hearing shut down and I'm sure my poor HOCM heart skipped more than it's normal beats.
Only you get to decide what direction to go, but you owe it to yourself to at least learn from an expert what your options are. I can say with confidence...nobody wants open heart surgery!
But I can also say with confidence if your HOCM is severe, it's not going to get better and the thought of facing a life-time (and I didn't know how long I had to live) of not being able to hardly walk, tie my shoes, eat a meal without feeling like I was going to die...that helped me make my decision.
Plus, being at the Mayo Clinic, where the finest HCM/HOCM doctors practice was truly comforting.
Here is a link to self refer: https://mayocl.in.1mtmR63
I asked my local cardiologist to refer me to the top two heart COE (Center of Excellence). I live on the other side of the Country in far Northern California. Do not let location be a reason to not at least try to be seen at a COE. In my opinion, and I do believe the world's as well, Mayo Clinic is THE top hospital for HCM and septal myectomy. Not every person is going to be successful on Camzyos, as you experienced. Not every person wants to keep taking higher doses of heart meds.
Can you ask your doctor to refer you to Mayo Rochester?