As a medical professional with expertise in cardiology, I can explain the causes of an NSTEMI, which stands for Non-ST-segment elevation myocardial infarction. An NSTEMI is a type of heart attack that occurs when there is a blockage in one or more of the coronary arteries, which supply blood to the heart muscle. However, unlike an ST-segment elevation myocardial infarction (STEMI), the blockage in an NSTEMI is not complete, and the heart muscle is not receiving an adequate amount of oxygen, but it is not completely cut off either. The causes of an NSTEMI are often related to the buildup of plaque in the arteries, known as atherosclerosis. Here's a step-by-step explanation of the process: 1. Atherosclerosis: This is a condition where fatty deposits (plaque) build up inside the arteries, causing them to narrow and harden. This reduces the flow of oxygen-rich blood to the heart. 2. Plaque Rupture: Over time, these plaques can become unstable and may rupture or crack. When this happens, the body's healing response causes a blood clot to form at the site of the rupture. 3. Blood Clot Formation: The clot can partially or completely block the blood flow through the coronary artery, leading to reduced blood and oxygen supply to a part of the heart muscle. 4. Heart Muscle Damage: If the blood flow is not restored quickly, the heart muscle can start to die, resulting in an NSTEMI. Risk factors for developing an NSTEMI include smoking, high blood pressure, high cholesterol, obesity, diabetes, lack of physical activity, and a family history of heart disease. read more >>

This is explained by the fact that NSTEMI and unstable angina are caused by partial (incomplete) coronary artery occlusions; a partial occlusion results in a reduction of coronary blood flow and this causes subendocardial ischemia (i.e ischemia that only affects the subendocardium).read more >>