Coronary artery disease

Coronary artery disease (CAD), also called coronary heart disease or ischemic heart disease, is a common type of heart problem. It happens when blood flow to the heart muscle is reduced because of a build-up of atheromatous plaque in the arteries of the heart. This is the most common of all cardiovascular diseases.

One main sign of CAD is angina, which is chest pain or discomfort that can spread to the shoulder, arm, back, neck, or jaw. Sometimes it feels like heartburn. In stable angina, these symptoms happen with exercise or stress, last only a few minutes, and get better with rest. Shortness of breath can also be a symptom, and sometimes there are no symptoms at all. In many cases, the first sign of CAD is a heart attack. Other possible problems include heart failure or an abnormal heartbeat.

Risk factors for CAD include high blood pressure, smoking, diabetes, lack of exercise, obesity, high blood cholesterol, poor diet, depression, and too much alcohol consumption. Doctors can help diagnose CAD using tests like an electrocardiogram, cardiac stress testing, and coronary angiogram. To lower the risk of CAD, it helps to eat a healthy diet, exercise regularly, keep a healthy weight, and not smoke. Medications and procedures like percutaneous coronary intervention or coronary artery bypass surgery may be used to treat severe cases. In 2015, CAD affected 110 million people and was the most common cause of death worldwide.

Signs and symptoms

The most common sign of this heart condition is chest pain or discomfort that happens during certain activities, like exercising or eating. This is called stable angina and is linked to narrowings in the heart’s blood vessels. Other feelings include tightness, heaviness, pressure, numbness, or squeezing in the chest. If these feelings change or become more frequent, it is called unstable angina and can be a warning sign of a more serious problem.

When the blood flow to the heart is greatly reduced, it can cause shortness of breath, sweating, nausea, or feeling dizzy. These are important signs that need quick medical help. Some people may have very strong symptoms, while others might not notice any changes at all.

Risk factors

Coronary artery disease happens when the arteries in the heart get clogged due to a build-up of plaque. This plaque forms because of a condition called atherosclerosis, where the arteries harden and collect cholesterol. Several things can increase the chances of getting this disease. Important risk factors include smoking, having diabetes, high blood pressure, high levels of cholesterol in the blood, being overweight or obese, and not getting enough exercise. Other factors like a poor diet, family history, stress, and drinking too much alcohol can also play a role. About half of all cases are influenced by genetics. Some less common factors being studied include certain health conditions and exposure to air pollution.

Air pollution, both indoors and outdoors, is a big contributor to deaths from coronary artery disease. In some parts of the world, like Southern, East, and West Africa, and South Asia, almost 40% of deaths from this disease are linked to bad air quality. Tiny particles from burning fossil fuels are especially harmful.

Different types of fats in our diet can also affect our heart health. Foods with trans fats and saturated fats, often found in processed and animal products, can lead to plaque build-up in the arteries. This reduces blood flow to the heart and can cause coronary artery disease.

The chances of getting coronary artery disease can also be influenced by genetics. Studies have found many genes that may increase the risk. Changes in certain RNA molecules have also been linked to this disease, affecting how the immune system and heart cells work.

Other factors that may increase the risk include certain health conditions like depression, experiences from childhood, and low levels of hemoglobin. In some populations, specific genetic changes have been linked to a higher risk of the disease. Additionally, having HIV can also increase the chances of developing coronary artery disease.

Pathophysiology

When blood flow to the heart is limited, the heart’s muscle cells can starve for oxygen. This lack of oxygen can cause these cells to die, which is known as a heart attack. Without new cells to replace the dead ones, the heart muscle can become damaged and scarred.

Coronary artery disease usually happens when the inner lining of the heart’s arteries hardens and stiffens due to a condition called atherosclerosis. This hardening can block blood flow and may lead to serious heart problems.

Diagnosis

The diagnosis of coronary artery disease depends on the symptoms a person has and the results of imaging tests. The first test doctors often use is an electrocardiogram (ECG/EKG), which helps check the heart’s electrical activity. Other tests like an X-ray of the chest, blood tests, and resting echocardiography might also be done.

For people who have symptoms but are not in danger, doctors can use several non-invasive tests to check for the disease. These include Computed tomography angiography (CTA), positron emission tomography (PET), single-photon emission computed tomography (SPECT)/nuclear stress test/myocardial scintigraphy, and stress echocardiography. These tests help doctors see if the heart’s blood vessels are narrowed. Sometimes, more detailed tests like coronary angiography are needed if the other tests are unclear or show a high risk of problems.

Stable angina is a common sign of this heart disease and causes chest pain during physical activity. Doctors can use cardiac stress tests to see how the heart works under stress. If needed, coronary angiography can show if there are narrow areas in the heart’s blood vessels that might need treatment like angioplasty or surgery.

When someone has severe chest pain and tests show changes in the heart’s electrical activity, doctors may identify an acute myocardial infarction. This is an emergency and needs quick treatment, such as coronary angiography and special procedures or medicines to help the heart.

There are different ways to check the risk of developing coronary artery disease, such as the Framingham Score, which looks at factors like age, cholesterol levels, and blood pressure. Genetic testing can also help predict risk.

Prevention

Up to 90% of heart problems can be avoided by making healthy choices. This includes doing regular physical activity, keeping a healthy weight, controlling blood pressure, eating nutritious foods, managing cholesterol levels, and not smoking. Being active can lower the risk of heart disease by about 25%. The American Heart Association says that getting good sleep is also important for heart health.

A healthy diet with lots of fruits and vegetables can lower the risk of heart disease. Eating foods like those in the Mediterranean diet or lots of fiber may also help. Avoiding foods with trans fats, found in some processed products, is important too. While exercise is very helpful for heart health, it’s not clear if doctors should spend time telling patients to exercise more.

For people who already have heart disease, making lifestyle changes like controlling weight, quitting smoking, and reducing stress can help prevent more problems. Regular aerobic exercise, such as walking or swimming, can lower the risk of serious outcomes from heart disease and improve cholesterol levels. However, using antibiotics to prevent further heart problems has been shown to be harmful and is not recommended.

Treatment

There are several ways to help manage coronary artery disease:

• Lifestyle changes can make a big difference.
• Medical treatment includes medicines such as cholesterol lowering medications, beta-blockers, nitroglycerin, and calcium channel blockers.
• Coronary interventions like angioplasty and coronary stent are also options.
• Coronary artery bypass grafting (CABG) is another choice for some people.

Medications

Common medicines include:

• Statins to lower cholesterol
• Nitroglycerin
• Calcium channel blockers and beta-blockers
• Antiplatelet drugs like aspirin

It’s important to keep blood pressure under control, aiming for less than 140/90 mmHg.

Aspirin

For people without previous heart disease, aspirin can help prevent a heart attack but does not change the overall risk of death. It is usually recommended for adults at higher risk for heart problems, such as postmenopausal women, men over 40, or those with high blood pressure, a family history of heart disease, or diabetes.

Anti-platelet therapy

Using Clopidogrel with aspirin can help prevent heart problems in certain situations, especially for those who have had a special type of heart attack called a STEMI. For others, the benefits are not as clear.

Surgery

For serious heart conditions, surgery can help. In some cases, coronary artery bypass grafts work better than other procedures. New techniques for surgery are also being used that may reduce certain risks.

Epidemiology

Coronary artery disease is the biggest cause of death around the world. In 2010, it caused over 7 million deaths, and by 2021, this number had risen to 9.1 million. It can affect people of any age, but it becomes much more common as people get older. Men are affected more often than women.

In the United States, coronary artery disease causes about 600,000 deaths each year. It is the most common reason people over 20 years old die in the country. Many health organizations are working to raise awareness about this serious condition.

Society and culture

People sometimes call this condition "hardening of the arteries" or "narrowing of the arteries". In Latin, it is known as morbus ischaemicus cordis (MIC).

There are groups like the Infarct Combat Project, an international nonprofit group started in 1998. They work to help reduce heart diseases through learning and studying.

In 2016, research looked at old papers from the Sugar Research Foundation. This group represents the sugar industry in the United States. In 1965, they paid for a review in the New England Journal of Medicine that didn’t talk much about how sugar might lead to heart disease. Instead, it focused on fat. This review affected how money was spent and advice given about healthy eating for many years.

Research

Further information: Atheroma and Atherosclerosis

Scientists are studying new ways to treat heart problems, including special treatments and stem-cell therapies. They have found important pieces of information on chromosome 17 and chromosome 9, but more work is needed to understand how these affect health.

Some researchers wonder if a certain germ called Chlamydophila pneumoniae might play a role in heart disease, but the proof is not clear. Using antibiotics for people who already have heart problems has not shown clear benefits.

Studies also look at how the body’s defenses might be involved in heart disease, but more research is still needed.