By Exclusion. It's generally a diagnosis of exclusion, when one can't find another reason for symptoms of angina. It would require a catheterization with coronary angiogram to exclude blockages in the larger coronary arteries on the surface of the heart. Also an echocardiogram might be done to exclude valvular heart disease. It's more common in women and treated usually with beta blockers such as metoprolol.
Cardiac testing. Microvascular angina occurs when there is a reduction in blood flow to the heart unrelated to blockages in the large arteries that provide oxygen and nutrients to the heart itself. This is related to problems with smaller arteries within the muscle of the heart. It can cause the same sort of chest discomfort. It is most commonly seen in diabetics and hypertensives with thick heart muscle.