The blockage of a coronary artery is usually caused by atherosclerosis, a form of coronary heart disease characterized by a buildup of fatty deposits along the inner walls of the arteries. Atherosclerosis is largely a disease of lifestyle and diet, i.e., a disease that can be prevented. Artery walls thicken and the passageways constrict, leading to a heightened possibility that an artery becomes completely blocked. This prevents the flow of oxygenated blood to your heart. The process is slow, usually as a result of a lifetime of poor eating and lifestyle habits, and takes several years before the "clogging" manifests into physical symptoms.
Vasospasms can also cause myocardial infarction. A vasospasm is a spontaneous and tight constriction of a coronary artery that can lead to heart attack. Such cases are rare, though. No one is quite sure what causes this spontaneous condition. Although it occurs most often in arteries that are diseased by atherosclerosis, vasospasms can occur in healthy arteries as well. Excessive cold, a moment of severe emotional stress, or certain medications can trigger a vasospasm. Cocaine use is also linked to sudden contractions of blood vessels, increasing the chance of this form of heart attack.
An episode of extreme hypertension (high blood pressure) can trigger a heart attack. Like vasospasm, this, too, is a rare occurrence.
