Coronary heart disease is the narrowing or blockage of the arteries and vessels that provide oxygen and nutrients to the heart. It is caused by a condition called atherosclerosis, which is the gradual build-up of fatty materials on the arteries' inner linings. The blockage that results from the build-up restricts blood flow to the heart. When the blood flow is completely cut off, a heart attack can occur.
Coronary heart disease also may be called coronary artery disease or, simply, heart disease. It is the leading cause of death in the United States among men and women.
When the heart works harder and needs more oxygen, the coronary arteries expand. But build-up of fatty materials, or plaque, from atherosclerosis causes the arteries to harden and narrow. If the arteries are unable to expand because of coronary artery disease, the heart is deprived of oxygen. The heart muscle cannot work properly without oxygen. The reduced blood flow and oxygen supply may cause angina, which is pain in the chest. It also may cause shortness of breath or other symptoms. Complete blockage or clotting at the site where the blood enters the heart can cause a heart attack.
According to the Centers for Disease Control and Prevention, about 610,000 people in the United States die of heart disease every year, 370,000 of them from coronary artery disease. Heart disease causes about 25% of deaths, making it the leading cause of death. About 735,000 people every year have a heart attack. Heart disease is the leading cause of death for people who are African American, Hispanic, and Caucasian.
Coronary heart disease is caused by atherosclerosis. Some risk factors for coronary heart disease cannot be changed, whereas others are tied to lifestyle choices.
Age is a major risk factor for death from coronary heart disease. Over 83% of people who die from coronary heart disease are over age 65. Gender plays a role too; men have a higher risk of heart attacks. Men tend to get heart disease earlier than women. Whereas men are at higher risk for coronary heart disease by about age 45, women are at risk for heart disease later in life, beginning at about age 55. People whose parents had heart disease also are at higher risk for coronary heart disease. Certain racial groups have higher risk as well, often because of a greater tendency toward obesity, high blood pressure, or diabetes.
Other risk factors can be affected by diet and lifestyle changes. Smoking is a big contributor to coronary heart disease. Not only do people who smoke have a two to four times greater risk of developing coronary heart disease than those who do not smoke, but they also have a higher risk of heart attack from the disease. In fact, a smokes and has coronary heart disease is twice as likely as a person who does not smoke and has coronary heart disease to die suddenly from the disease.
A high-sugar diet is associated with risk of heart disease. British researcher John Yudkin argued that sugar intake was more significant than fat intake back in the 1970s; more recent studies have supported his hypothesis. Researchers at the University of Surrey in 2017 found that putting subjects on a high-sugar diet for 12 weeks produced changes in fat metabolism associated with increased risk of coronary heart disease. An article published in Progress in Cardiovascular Diseases in 2016 observed that diets high in sugars tripled the risk of death from cardiovascular disease. The authors claimed that advice to reduce dietary fat could actually increase the risk of heart disease, especially if the fat is replaced with sugar, and suggested that dietary guidelines should instead focus on reducing intake of sugars.
Hypertension, or high blood pressure, is strongly associated with risk of coronary heart disease. High blood pressure makes the heart work harder and weakens it over time. The American Heart Association notes that high blood pressure is linked with metabolic syndrome, or insulin resistance syndrome. Metabolic syndrome is diagnosed when a patient has any three of these risk factors:
High blood sugar can eventually lead to type 2 diabetes, which is a serious risk for coronary heart disease and cardiovascular disease, which includes other disease to other arteries throughout the body. About three-fourths of people with diabetes die from heart disease or blood vessel disease. The link between insulin and metabolic syndrome is one of the reasons researchers now recommend reducing sugar. In fact, there is such a strong association among all these conditions that many experts believe heart disease, hypertension, and type 2 diabetes are all the result of high insulin levels.
Elevated blood cholesterol levels have long been said to be a risk factor for developing coronary heart disease. This has led governments and medical bodies to recommend that people consume a diet low in fat, particular in saturated fat. However, researchers have since found that cholesterol levels are not particularly tied to cardiovascular disease. About half of people who suffer heart attacks have normal cholesterol levels, and a number of studies have found an inverse relationship between high cholesterol and mortality from heart disease.
Stress also may play a role in coronary heart disease risk. It has been suggested that stress may even be the most significant risk factor. Drinking too much alcohol can cause some of the conditions listed above and lead to heart failure. However, moderate amounts of alcohol, described as about 1.5 fl. oz. (.044 L) of 80-proof spirits, 1 fl. oz. (.03 L) of 100-proof spirits, 4 fl. oz. (.12 L) of wine, or 12 fl. oz. (.36 L) of beer per day, are associated with a lower risk of heart disease. The American Heart Association does not recommend that people who do not drink begin drinking or that anyone increase alcohol intake to meet these amounts, however.
The restricted blood flow to the heart caused by narrowing arteries may not produce any symptoms at first, and many people are completely unaware that they have coronary heart disease. As the plaque builds up, symptoms begin to develop. One of the first signs may be chest pain that is triggered by physical or emotional stress. This pain often is referred to as angina. The pain feels much like pressure or tightening in the chest or it may be felt in the arm, neck, jaw, shoulder, or back. Sometimes the pain is confused with indigestion. Women may notice pain more often in the back or arm than in the chest, and the pain may be brief and pass quickly.
Shortness of breath also is a symptom of coronary heart disease. This results from the heart's decreasing ability to pump enough blood to the body to meet its needs. The person with shortness of breath also may feel very tired.
The most serious symptom of coronary heart disease is heart attack. Although some heart attacks start suddenly and are clearly occurring, most start slowly with uncertain symptoms. Discomfort in the center of the chest that lasts for several minutes that feels like squeezing, fullness, or pain is a sign that a heart attack is occurring or about to occur. The pain also may go away and come back. The pain may occur in one or both upper arms, the back, neck, jaw, or stomach. A person may experience shortness of breath with or without chest pain. Some people break out in a sweat or experience nausea or lightheadedness.
A physician will ask questions about medical history, symptoms, and relatives with heart disease, as well as diet and lifestyle. A physical examination and routine blood tests also may be ordered as part of the evaluation. In addition, several examinations can be done to diagnose and evaluate coronary heart disease. These include:
There are many ways to treat coronary heart disease, and the choice of treatment depends on the cause of the disease and its severity. Treatment ranges from lifestyle changes and use of medication to surgical procedures. People with less severe disease and fewer risk factors may be able to manage their disease through lifestyle changes and drug therapy. Changes in diet and an increase in exercise, as well as quitting smoking, can help control coronary heart disease. Often, all treatment procedures are used. Lifestyle factors such as diet and exercise are first-line prevention and treatment methods. They are to be continued both after beginning medications and following surgery.
Medications used to treat coronary heart disease include:
Surgery or other procedures also may be recommended to treat coronary heart disease. A physician may use a catheter to guide a tiny balloon into the artery. Once in place, the balloon is inflated and widens the artery by pushing the plaque up against the artery wall, Next, a stent, or mesh tube, is placed in the widened area to help keep the artery opened and clear for adequate blood flow.
Research published in The Lancet in 2017 found that stents are ineffective at treating chest pain. As a result, cardiologists started to question whether stents were actually good therapy for heart patients.
Coronary artery bypass surgery reroutes, or bypasses, blood flow around the arteries that have clogged to improve blood flow to the heart. To perform the procedure, the surgeon takes a healthy blood vessel from another part of the body and uses it to create a detour around the clogged artery. This procedure requires open heart surgery and is reserved for people with multiple areas of artery blockage.
Heart attacks from coronary heart disease require emergency medical treatment.
Nutrition is key to preventing and controlling coronary heart disease. There is, however, considerable disagreement among experts on the best nutritional strategies. Cardiologists and nutritionists have long recommended a low-fat diet. The American Heart Association's DASH diet, which is recommended for lowering blood pressure, is low in fat. Other experts claim that this advice actually causes heart problems because a low-fat diet is inherently high in carbohydrates. They recommend instead a low-carbohydrate diet that is especially low in sugar, but high in fat.
The American Heart Association recommends that adults get no more than 300 mg of cholesterol a day in their diet and that those with heart disease get no more than 200 mg a day. In terms of blood cholesterol, it is most important to limit intake of saturated fats. Eating fat-free or low-fat dairy and meat products and opting for oils rich in polyunsaturated or monounsaturated fatty acids (for example, olive, sunflower, rapeseed oil) will help to keep cholesterol levels in check.
Controlling blood pressure helps prevent or manage coronary heart disease. A diet low in sodium (salt) and high in fruits, vegetables, and whole grains helps to control blood pressure. The DASH diet is a balanced approach to controlling hypertension.
Instead of a low-fat diet, many experts recommend a low-carbohydrate high-fat diet to reduce the risk of heart disease. Some researchers have argued that low-fat diets are inherently bad for humans and unsupported by scientific evidence, and that a low-carbohydrate high-fat diet instead is good for the health. These diets are based on the premise that high carbohydrate consumption increases levels of insulin in the blood whereas fat does not. Insulin is a hormone that helps the body convert food into energy in the form of glucose or sugar.
Eating sugars and simple carbohydrates can contribute to weight gain and raise blood triglyceride levels, increasing risk of coronary heart disease. It is important for people with diabetes to control their intake of white bread, bagels, cakes, soft drinks, and other carbohydrates. Whole-wheat breads, brown rice, and legumes provide more fiber and slowly absorbed carbohydrate than refined carbs and can aid in appetite control and help regulate blood glucose levels. People with high intakes of whole-grain foods seem to be at lower risk of suffering from coronary heart disease. Combining whole grains with a diet that emphasizes fruit, vegetables, and oily fish has been shown to be especially effective in reducing the risk of heart disease.
Some patients with coronary heart disease will be referred for cardiac rehabilitation, particularly following bypass surgery or after experiencing angina or a heart attack. The rehabilitation may consist of an exercise plan to help regain stamina safely based on individual ability and needs, as well as education, counseling, and training. Training may include ways to better manage stress and other lifestyle factors that contribute to coronary heart disease.
Coronary heart disease can be successfully managed and treated in many cases. Advances in diagnosis and techniques such as stenting have helped to improve the lives of people with the disease, bringing about a significant decline in death rates from coronary heart disease since the mid-1980s. As the leading cause of death in the United States, however, coronary heart disease is a serious condition that is best prevented and requires careful management and attention once diagnosed. The more risk factors a person has, the worse the prognosis.
Preventing coronary heart disease begins with identification of common risk factors and taking action to reduce the impact of these factors (for example, cholesterol or blood pressure reduction). Management of the primary contributing factors helps prevent the advancement of atherosclerosis and eventual development of coronary heart disease. By quitting smoking, moderating alcohol use, controlling blood pressure, preventing diabetes, and maintaining healthy cholesterol levels, individuals can prevent many of the causes of coronary heart disease. Maintaining a healthy body weight by eating a balanced diet with healthy-sized portions and participating in regular physical activity helps to prevent the disease. Those with known hereditary or other risk factors for coronary heart disease should have regular physical examinations with their physicians and should pay careful attention to the signs and symptoms of coronary heart disease and heart attack.
Omega-3 fatty acids have been found to help prevent heart disease in people at high risk. The American Heart Association recommends eating two servings of fatty fish (e.g., salmon, herring, trout, mackerel, sardines, tuna) every week. People who do not eat fish may wish to talk to their doctors about taking fish oil supplements.
Some doctors are now advising patients to reduce their sugar intake to lower their insulin levels and the corresponding risk of metabolic syndrome. Many even recommend a low-carbohydrate, high-fat diet, believing that the low-fat dietary recommendations of the past decade have actually caused the obesity epidemic and associated conditions such as heart disease.
See also DASH diet ; Diet and disease prevention ; Heart-healthy diets ; High-fat, low-carb diets ; Hypertension ; Obesity .
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Teresa G. Odle
Revised by Amy Hackney Blackwell, PhD