What causes myocardial infarction in terms of angina?

Myocardial infarction occurs when there is a significant disruption in blood flow to the heart muscle, leading to cell death due to lack of oxygen. One of the primary causes of this disruption is a complete blockage of the coronary arteries, often due to a blood clot that forms on a ruptured plaque in atherosclerosis. When a coronary artery is fully blocked, blood cannot reach the sections of the heart muscle it supplies, which can result in irreversible damage or infarction.

In terms of angina, which is chest pain due to reduced blood flow to the heart often occurring during times of increased physical or emotional stress, the underlying issue is typically related to narrowed arteries that cannot accommodate the increased demand for blood. However, angina usually does not lead to permanent heart damage. In contrast, a complete blockage is a more critical situation that can transition from angina to myocardial infarction, especially if the coronary artery remains blocked long enough to deprive the heart muscle of oxygen.

Other factors such as spasms in the coronary arteries and emotional stress might contribute to angina or transient episodes of reduced blood flow but do not directly result in the full blockage necessary for causing a myocardial infarction.