Thanks for posting query.
Heart has 49% life left means ejection fraction
of his heart is 49%.Normal ejection fraction is 55%-70%.Ejection fraction is the capacity of heart to pump blood from heart and amount of blood that is remaining in heart after pumping.
Due to heart attack
his heart has damaged to some extent but as he underwent balloon angioplasty
there are chances of improvement in ejection fraction up to some extent.
Also 49% ejection fraction is good enough to survive normal life and for daily activities.
For detailed assessment of viable myocardium you can go for stress thalium scan if not contraindicated.
At present you need to continue aspirin
.ACE inhibitors,beta blockers and anti-anginal drugs.
Consult with cardiologist for definitive management.
Hope this could help you.
Wish you good health.