Final answer:
In USA and NSTEMI, there is ultimately a decrease in oxygen supply.
Step-by-step explanation:
In the case of USA (Unstable Angina) and NSTEMI (Non-ST Segment Elevation Myocardial Infarction), there is a decrease in oxygen supply.
Even without total blockage, vessel narrowing leads to ischemia, which is a reduced blood flow to the tissue region 'downstream' of the narrowed vessel. Ischemia ultimately leads to hypoxia, which is a decreased supply of oxygen to the tissues.
For example: If there is a blockage in the coronary artery, it can lead to a decrease in blood flow and oxygen supply to the heart muscle. This can result in symptoms such as chest pain or angina.