Hello and thank you for using HCM.I carefully read your question and I understand your concern.
I will try to explain and give you my opinion.
As you describe your mother had previously done
angiography and is under treatment. This means that she didn't have any serious
artery stenosis at that time but only small
plaque.
But the situation changes in tre years.If the chest pais has started than the situation must be verified again.
The gold Standart to diagnose coronary artery disease is normal coronary aniography.
Coronary angio ct is an examination that helps to exclude a coronary artery disease in atypical cases but it has lower sensitivity for making full diagnosis. It only rises suspicion . If it finds a problem the definite diagnosis is only made by normal angiogram.
So, if we already know that a plaque has been there, than the angiography is the gold standard for diagnosis.
It might be possible that the plaque is biger now and it might need intervention so again the only way is normal angiography.
Hope I was helpfull.
Best regards, Dr.Ervina.