As others have said, it is normal for people suffering, not just MI but other illnesses too. Not so normal for "normals".

I have had sui thoughts since my late 20s and now going on 60, still feel the same but I keep going and I have learned that not wanting to continue living does not necessarily mean you want to die. For me it's an escape hatch in case the going gets too rough, always in the back of my mind. But I have survived many things I never would have thought I could, health issues and other life issues. On the one hand I am proud of my accomplishments. On the other, I don't know if I can deal if anything major comes up. I think the will to survive is there inside us no matter how we feel, but sometimes people do give up and do the deed.

All I can say is you never know what tomorrow will bring so it is worth sticking around.