An angiogram (CT or cath) test examines the coronary arteries for any blockage. Blocked coronary ateries compromise the blood flow to the heart tissues. A lack of blood flow to the heart cells causes chest pains. If there are blockages, a stent implant (usually done at time of angiogram) will increase the diameter of the occlusion/occlusions permitting more blood to the deficit area. Sometimes the area of blockage can not be stented because of location, tortuous segment, too long, etc...then a bypass surgical operation may be the only remedy.
Alternatively, some people find relief from chest pain with medication. Nitrate medication can/will dilate the vessels permitting more blood to flow to the area in question and no intervention may be a good option.. I have blocked arteries and medication prevents chest pain (going on 5 years).