A heart attack occurs when the flow of blood to the heart is severely reduced or blocked. The blockage is usually due to a buildup of fat, cholesterol, and other substances in the heart, known as plaques. If a plaque breaks open, it can cause a blood clot in the heart, which may block the supply of blood to the heart, triggering a heart attack. Coronary heart disease (CHD) is the leading cause of heart attacks. CHD is a condition in which the coronary arteries, the major blood vessels that supply the heart with blood, become clogged with deposits of fats such as cholesterol and other substances. Other factors that can increase the risk of heart attacks include:

• Smoking
• A high-fat diet
• Diabetes
• High cholesterol
• High blood pressure (hypertension)
• Being overweight or obese

A less common cause of heart attacks is a lack of oxygen (hypoxia) . If levels of oxygen in the blood decrease due to carbon monoxide poisoning or a loss of normal lung function, the heart will not receive enough oxygenated blood. This will result in the heart muscles being damaged, triggering a heart attack.

In summary, heart attacks are caused by a blockage in the arteries that supply blood to the heart, usually due to a buildup of plaques. CHD is the leading cause of heart attacks, and other factors that can increase the risk of heart attacks include smoking, an unhealthy diet, diabetes, high cholesterol, high blood pressure, and being overweight or obese.