Angina and a Heart attack are different.
Both relate to the blood flow through the coronary arteries which bring blood to the heart muscle;
with angina the blood flow is reduced and the heart must work harder, its temporary with little pain.
With a Heart attack the blood flow is suddenly cut off when an artery is blocked, there is more sever pain and it lasts longer, you must seek help fast.(you will know when you are having a heart attack, it's much different feeling, a feeling you never felt in your whole life)
Angina does NOT permanently damage the heart, but heart attacks do.
Most people that have angina don't have a heart attack, but people that had a heart attack can develop angina after one.
I'm guessing the doctor did some tests to make sure there isn't any significant blockadges in your moms arteries. A blood test would show him is she had a heart attack, and the ECG can tell him a lot about the heart. But the best way to make sure the arteries are clear is with an Angiograph, but these do have a little risk, so there only done if the other tests show signs of blocked arteies.
Thank you so much or clarifying my doubt. If you don't mind can you give me some suggestions and diet that should be taken??