What risks can a Left Anterior Fascicular Block hold in the future and can it be signs for more heart problems?

Im 21 years old and i was diagnosed with Left Anterior Fascicular Block after severe chest pains loss of stamina disorientation, difficulty performing at high altitudes, and difficulty focusing.  I dont have the normal lifestyle of a 21 yo. Im currently serving as an infantry personel in the usmc.  I was wondering what this could mean as of now and my personal performance,, could be the sign of another heart disease that doesnt show up on an ekg, how much of a health risk does it pose during strenuous physical avtivity and what health risks does this pose for the future.  Also i have been smoking for about 7 years at bout 1 to two packs a day and my family does have history of a LBBB and my grandfather had 7 stints put in his heart.  Any info on this would be helpful.  thankyou