Thanks for writing in.
I am a qualified and certified cardiologist and I read your question with diligence.
Yes you are right: your grandma is having what we call is unstable angina
is known to occur in enlarged heart
. She is in urgent need of a specialist's help. If you can get an appointment with cardiologist or medical specialist with interest in cardiologist, he/she can determine the severity of problems and need for how intensive medical therapy. Important question which demands an answer is does she need hospitalization? Then comes the issue of intervention to restore the blood supply to heart. These issues can be resolved by a specialist. Good Luck.
With Best Wishes
Dr Anil Grover