Coronary heart disease (CHD) is the leading cause of death for both men and women in the United States. CHD is caused by a narrowing of the coronary arteries that supply blood to the heart, and often results in a heart attack.

Each year, about 1.1 million Americans suffer a heart attack. About 460,000 of those heart attacks are fatal. About half of those deaths occur within 1 hour of the start of symptoms and before the person reaches the hospital.

Fortunately, everyone can take steps to protect their heart–and their life or that of someone else. The key is seeking medical care as soon as possible.

This Web page tells you about heart attack and the steps you can take to increase your chances of survival. You’ll learn why a fast response to the signs of a heart attack is crucial to save lives and limit heart damage.

The heart works 24 hours a day, pumping oxygen- and nutrient-rich blood to the body. Blood is supplied to the heart through its coronary arteries. In coronary heart disease (CHD), plaques or fatty substances build up inside the walls of the arteries. The plaques also attract blood components, which stick to the artery wall lining. Called atherosclerosis, the process develops gradually, over many years. It often begins early in life, even in childhood.

The fatty buildup or plaque can break open and lead to the formation of a blood clot that seals the break. The clot reduces blood flow. The cycle of fatty buildup, plaque rupture, and blood clot formation causes the coronary arteries to narrow, reducing blood flow.

When too little blood reaches the heart, the condition is called ischemia. Chest pain, or angina, may occur. The pain can vary in occurrence and be mild and intermittent, or more pronounced and steady. It can be severe enough to make normal everyday activities difficult. The same inadequate blood supply also may cause no symptoms, a condition called silent ischemia.

If a blood clot suddenly cuts off most or all blood supply to the heart, a heart attack results. Cells in the heart muscle that do not receive enough oxygen-carrying blood begin to die. The more time that passes without treatment to restore blood flow, the greater the damage to the heart.

Heart attacks strike both men and women. However, some persons are more likely than others to have a heart attack because of their "risk factors." Risk factors are behaviors or conditions that increase the chance of a disease. Some of the risk factors for heart attack are beyond your control, but most can be modified to help you lower your risk of having a first–or repeat–heart attack.

Risk factors do not add their effects in a simple way. Rather, they multiply each other’s effects. So, it is very important to prevent or control risk factors that can be modified. If you have one or more of these factors, see your health care provider to find out how to reduce your risk of having a first or repeat heart attack.