There's more to heart disease than just smoking. Among or things heredity plays a part, as in my case there's a family history of heart attacks. I smoked for about 28 years. For around half of that period I regularly did amphet, as well as other stimulants
. I suppose that makes it maybe 14 years of heavy amphet and tobacco
use. I was 45 when I had the heart attack.
It's difficult to predict exactly what will happen and when to each individual, but my feeling is that a lot of people have done tremendous damage to their hearts and lungs by smoking heavily on speed or meth
. There is a plethora of associated disease.
Luckily the surgery sorted me out and has left me with a healthy heart. You're young enough, so should be OK if you can avoid smoking.