20 % Blockage

Hi I am new to this forum but I wanted to find out a couple things.
In december of this last year I came to find out that I had a 97 % blockage in my right artery to my heart. They put a stent in. They said the had to use the longest stent they had because I guess it was a pretty long blockage. Now my question is. Did the stent just barely work or would they have surely made sure it was bigger than the clot itself. I guess what I mean is is it possible that some of that blockage is like sticking out the ends of the stent?

Also my cardiologist told me the other day that my left arteries are 20% blocked. Now what does that mean to me? Does that mean it would take years for that to clog off to a point where I would need another stent or bypass or is it like my old cardiologist said and it can happen again in minutes. I guess they found those other blockages when they did the stent but no one ever told me about them until I switched cardiologists this week.

Thanks so much for any replys
jenni