It's been awhile since i read specifics about pec minor syndrome , but I am pretty sure I have a form of it. Not surgical for me - but sticky fascia.

Sharon Butler {in her RSI book {in libraries}she has a website too} talks about fascia & adhesions and how important doing stretches for the pec minor/arm pit area are. Her book really explained a lot for me.

If you think it applies for you - in our useful stickys is a description of laying out on the floor with arm out to the side {as tolerable} and if you can do that with not sx increase then move up to laying on a rolled towel or foam roll cylinder.
I even use my inflatable exercise ball and lay face up and face down to stretch spine both ways. 15 mins or so each way.
I had to do this stuff many x's a day during my bad time- and still do when I feel any tightness coming on.

anything that will gently encourage the chest to open - the shoulders to drop back and down - laying down like that uses gravity and you are able to focus on relaxation and diaphragmatic breathing.