Dear sir as described by you your wife develop chest heaviness and shortness of breath after exertion this is very suggestive of ischemic heart disease . You have not mentioned her age, weight, BP whether she is diabetic or have dyslipidemia etc these are risk factor for ischemic heart disease . Diagnosis of angina that is pain of cardiac origin is clinical . This means its only on the basis of symptoms . You may get ecg echocardiography and angiography absolutely normal. .now she is on some cardiac medicine and as said by you she is feeling better. This is also suggestive of cause in heart.but apart from these two medicine she should also be given aspirin and statines . Discuss about this with your doctor if they have started treatment for ischemic heart disease then why half hearted . Along with all this check for anaemia most of females are anaemic and it will produce similar symptoms . Hope this will help.