Medicare Approval for surgery

So I am new...have an appointment with surgeon at Lahey Clinic in Burlington, Ma. next week. Fairly open mind as to which surgery would be best for me, which is a switch since only yesterday. I had thought lap band was what I would consider until I met with my friend who has been very successful since r n y surgery 5 years ago. I have known a couple people who love their bands...but now am worried if I do that if I might be one of the unfortunate people with complications...and since I am 70 I don't want to be facing that at 81 when I would be more of a surgical risk. My BMI is just 40 and I have no co-morbid conditions. Worried that insurance may not cover me since my BMI has not been consistently this high for past 5 years.

Thanks for any feedback, suggestions and your experiences with Medicare (assuming there might be at least a few of you old enough to have Medicare as your primary insurance) lol

Christine (mojaleski is my screen name nickname)