Does my inappropriate sinus tachycardia and occasional sharp chest pain put me at risk of a heart attack even though i'm only 25?

Depends: What's "inappropriate sinus tach?" at age 25 life's exciting and the heart can go bounding from time to time. Occasional sharp chest pain in a youngster that feels like a knife when you breathe in is usually "stitch" from a folded pleura, relieved by inflating the lung to the maximum; it's not heart-related. Life's too short to worry without reason; insist your physician give you solid answers!

Unlikely: Unlikely at your age unless you have a strong family history. However, the cause of your symptoms should still be investigated, as there may be something that in the long run may be harmful.

Maybe: You should have a complete evaluation by a cardiologist to determine the extent of your risk factors, and then have a plan that reduces those risks.