I quit cigarettes3 months ago. i'm using a vaping pen with 0 nicotene. i had 3 stints in my lad in 2012. how bad is this for me?

Probably okay: I commended you on quitting smoking. That is the best decision you can make to improve your heart health. It's still uncertain if e-cigs have any long-term effects, but I think the benefits of quitting smoking is so much better.

Vaping: Vaping even 1 nicotine-free electronic cigarette (e-cigarette) “can produce transient changes in blood vessels similar to those seen in early atherosclerosis” REF: https://www.medscape.com/viewarticle/917031. Don't recommend vaping.