Hello and hope you are doing well.
You must be referring to small vessel disease, it is a condition in which the larger arteries are normal and the small arteries in the heart become narrowed. It can be detected by the Endothelial dysfunction test, wherein dye is injected into the artery that causes the small vessels in the heart to open and then the blood flow through those vessels is measured. Although this test is invasive, it's a good way to detect small vessel disease. It is unlikely to cause problems related to the valves.
Hope this helped and do keep us posted.