Hey there

CA is a difficult course which has no doubt and students takes attempts to clear it. But in your case you were consistently preparing for CA and taking attempts which you can show at the time of interview because in MBA colleges they first ask you about your gap and the reason of the gap. If you'll be able to present yourself as productive in those 3 years then you may have chances of getting into iims but that would be really difficult in your case. Your good performance in CAT is all you have to get into good MBA colleges.

Eligibility for iims

https://www.google.com/url?sa=t&source=web&rct=j&url=https://bschool.careers360.com/articles/iim-admission-criteria/amp&ved=2ahUKEwj9yNuMhorlAhUY448KHby6DiwQFjABegQIDBAH&usg=AOvVaw2PS5YUHetdxNgSi3ef4_9N&ampcf=1&cshid=1570447975462

Good luck