Understanding Coronary Artery Disease
By National Institutes of Health
Coronary artery disease (CAD) is the leading cause of death in the United States for both men and women. Each year, more than half a million Americans die from CAD.
Coronary artery disease is a condition in which plaque builds up inside the coronary arteries. These arteries supply your heart muscle with oxygen-rich blood. Research suggests that CAD starts when certain factors damage the inner layers of the coronary arteries.
Risk Factors for CAD
Unhealthy blood cholesterol levels. This includes high LDL cholesterol (sometimes called bad cholesterol) and low HDL cholesterol (sometimes called good cholesterol).
High blood pressure. Blood pressure is considered high if it stays at or above 140/90 mmHg over a period of time.
Smoking. This can damage and tighten blood vessels, raise cholesterol levels, and raise blood pressure. Smoking also doesn't allow enough oxygen to reach the body's tissues.
Insulin resistance. This condition occurs when the body can't use its own insulin properly. Insulin is a hormone that helps move blood sugar into cells where it's used.
Diabetes. This is a disease in which the body's blood sugar level is high because the body doesn't make enough insulin or doesn't use its insulin properly.
Overweight or obesity. Overweight is having extra body weight from muscle, bone, fat, and/or water. Obesity is having a high amount of extra body fat.
Metabolic syndrome. Metabolic syndrome is the name for a group of risk factors linked to overweight and obesity that raise your chance for heart disease and other health problems, such as diabetes and stroke.
Lack of physical activity. Lack of activity can worsen other risk factors for CAD.
Age. As you get older, your risk for CAD increases. Genetic or lifestyle factors cause plaque to build in your arteries as you age. By the time you're middle-aged or older, enough plaque has built up to cause signs or symptoms. In men, the risk for CAD increases after age 45. In women, the risk for CAD risk increases after age 55.
Family history of early heart disease. Your risk increases if your father or a brother was diagnosed with CAD before 55 years of age, or if your mother or a sister was diagnosed with CAD before 65 years of age. Although age and a family history of early heart disease are risk factors, it doesn't mean that you will develop CAD if you have one or both.
Other factors also may contribute to CAD. These include:
Sleep apnea. Sleep apnea is a disorder in which your breathing stops or gets very shallow while you're sleeping. Untreated sleep apnea can raise your chances of having high blood pressure, diabetes, and even a heart attack or stroke.
Stress. Research shows that the most commonly reported "trigger" for a heart attack is an emotionally upsetting event—particularly one involving anger.
Alcohol. Heavy drinking can damage the heart muscle and worsen other risk factors for heart disease. Men should have no more than two drinks containing alcohol a day. Women should have no more than one drink containing alcohol a day.
Too much fat. High levels of fats called triglycerides in the blood also may raise the risk of CAD, particularly in women.
Causes of Coronary Artery Disease
When damage to the arteries occurs, your body starts a healing process. Excess fatty tissues release compounds that promote this process. This healing causes plaque to build up where the arteries are damaged.
Over time, the plaque may crack. Blood cells called platelets clump together to form blood clots where the cracks are. This narrows the arteries more and worsens angina or causes a heart attack.
The buildup of plaque in the coronary arteries may start in childhood. Over time, this buildup can narrow or completely block some of your coronary arteries. This reduces the flow of oxygen-rich blood to your heart muscle.
A common symptom of CAD is angina. Angina is chest pain or discomfort that occurs when your heart muscle doesn't get enough oxygen-rich blood.
Angina may feel like pressure or a squeezing pain in your chest. You also may feel it in your shoulders, arms, neck, jaw, or back. This pain tends to get worse with activity and go away when you rest. Emotional stress also can trigger the pain.
Another common symptom of CAD is shortness of breath. This symptom happens if CAD causes heart failure. When you have heart failure, your heart can't pump enough blood throughout your body. Fluid builds up in your lungs, making it hard to breathe.
The severity of these symptoms varies. The symptoms may get more severe as the buildup of plaque continues to narrow the coronary arteries.
Some people who have CAD have no signs or symptoms. This is called silent CAD. It may not be diagnosed until a person show signs and symptoms of a heart attack, heart failure, or an arrhythmia (an irregular heartbeat).
Coronary Artery Disease Research
Scientists continue to study other possible risk factors for CAD. High levels of a protein called C-reactive protein (CRP) in the blood may raise the risk for CAD and heart attack. High levels of CRP are proof of inflammation in the body. Inflammation is the body's response to injury or infection. Damage to the arteries' inner walls seems to trigger inflammation and help plaque grow.
Research is under way to find out whether reducing inflammation and lowering CRP levels also can reduce the risk of developing CAD and having a heart attack.
The National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health, "Heart Failure" section, provides leadership for a national program in diseases of the heart, blood vessels, lung, and blood; blood resources; and sleep disorders.