What typically causes a heart attack?

A heart attack, medically known as a myocardial infarction, primarily occurs due to a complete blockage of one or more coronary arteries. This blockage is often the result of plaque buildup, which consists of fat, cholesterol, and other substances that can constrict the artery. When a plaque ruptures, it can lead to the formation of a blood clot that obstructs blood flow. This blockage deprives the heart muscle of necessary oxygen, resulting in tissue damage or death.

The other scenarios presented do not directly cause a heart attack: rapid fluctuations in blood pressure, while they can be harmful, do not typically lead to the immediate blockage of arteries that precipitates a heart attack. Severe allergic reactions usually cause different acute responses in the body, not necessarily linked to coronary artery issues. Lastly, although excessive physical activity can increase heart strain, it is not a direct cause of heart attacks unless accompanied by underlying cardiovascular problems or other risk factors.