Hypertrophic Obstructive Cardiomyopathy and Septal Myectomy

I have had hypertrophic cardiomyopathy since I was a teenager. Now they are saying it is hypertrophic obstructive cardiomyopathy. I had a subcutaneous ICD put in around May of 2018. I have done numerous echos, ekgs, a tee echo, the test where they went through my wrist and not my groin. They are saying my septal muscle is almost 4cm thick and are recommending me to have a septal myectomy. I have already seen the surgeon but I am scared to have this procedure done as it is open heart surgery. Has anyone had the septal myectomy? what were the outcomes? DId it make you better and improve your symptoms? Also I have been experiencing a lot of nasal issues and post nasal drip. not sure if this is because of my heart condition. I have never had it this bad.