Hi and yes I was on it for almost 10 years. It was a blessing and ultimately became one of the reasons I got a transplant earlier when it became toxic to me.
I took it for almost 10 years just a few months short. Started in 2008 about Jun I remember and its why I was raised to 1b just before my transplant in Jan 2018.
It did damage my Thyroid and Had to be removed. But it was the IV types of Amiodarone that was keeping me alive also towards the end.

Most of the time I was taking it in pill form and took it for over 9 years with no problems. I found out later it has a tendency to also discolor the tops of my ears a very light blue. I never noticed that part until a doctor on my transplant team told me. It is well known to have some strong side effects but also the best go to medication for heart rhythm problems. I would say that long term use can bring on problems. Also when in the Hospital awaiting a transplant i was on a very high dose only available in IV form and that's what became toxic to me. Can I mask why your asking about it? Are you having some heart rhythm issues? Also is your doctor only using it short term? Let me know if I can help further. I might also add that when I first needed it my doctor tried a few others prior to this one but I developed rashes with the others. I was also on Mexiletine for rhythm problems at the same time as the amiodarone.
Blessings