Coronary artery disease (CAD) is the most common type of heart disease and occurs when plaque buildup narrows or blocks one or more of the arteries that supply blood to the heart. The term is often used interchangeably with coronary heart disease (CHD).
Specifically, CAD is a problem with one or more of the arteries that supply the heart muscle, which is the muscular layer of the heart. This is the thickest layer of tissue in the organ and consumes more oxygen than the rest of the heart, and therefore requires the most blood flow.
According to the Centers for Disease Control and Prevention (Opens in a new tab) (CDC), 382,820 people died in the United States of coronary heart disease in 2020, while 20.1 million adults age 20 and older are living with the condition.
What causes coronary artery disease?
Coronary artery disease is caused by a process known as atherosclerosis, in which plaque builds up in the inner walls of the arteries, causing them to narrow and become hard. This blocks blood flow, and the blockage can quickly worsen if a piece of plaque breaks off and causes a blood clot.
One factor that increases the risk of atherosclerosis is the long-term presence of high concentrations of low-density lipoprotein (LDL) cholesterol in the blood. These high levels can result from a relative deficiency of LDL receptors, which are proteins on the membranes of various cells of the body, particularly liver cells. LDL receptors pick up LDL from the blood, causing its contents — cholesterol and fat molecules called triglycerides — to be taken into the cell and out of the blood. Thus, the deficiency of these receptors leads to high levels of LDL cholesterol in the blood.
Elevated levels of low-density lipoprotein (LDL) cholesterol provoke and worsen what doctors call atherosclerotic cardiovascular disease, an umbrella term for atherosclerotic changes that can develop in blood vessels throughout the body; This includes CAD, which specifically affects the coronary arteries.
Other factors that can cause hardening of the arteries include factors that are out of control Type 2 diabeteshigh blood pressure (hypertension) and tobacco use.
What are the symptoms of coronary artery disease?
Symptoms of coronary artery disease generally don’t appear until narrowing and hardening of the coronary arteries begins to block blood flow to the myocardium (the muscular layer of the heart).
When this blockage occurs, it can result in angina—chest pain or heaviness in the chest that develops when the heart doesn’t get enough oxygen—as well as pain in other locations, such as the neck, shoulder, or arm. Angina can be stable in onset, which means that it generally occurs only with exertion associated with physical activity or emotional stress and the force of each contraction of the heart. However, this can progress to unstable angina, a type of acute coronary syndrome (ACS), which is a group of conditions associated with a sudden decrease in blood flow to part of the heart.
Colloquially known as a “heart attack,” the spectrum spans the less severe subtype, unstable angina. to intermediate subtype, non-ST elevation myocardial infarction (NSTEMI); to the more severe subtype, ST-elevation induced myocardial infarction (STEMI).
According to the Mayo Clinic (Opens in a new tab)Symptoms of coronary artery syndrome caused by coronary artery disease may include:
- dyspnea (difficulty breathing or shortness of breath)
- Chest pain or heaviness in the chest
- Pain in other locations, such as the neck, shoulder, or arm
- dizziness or fainting
- sudden sweating
How is coronary artery disease diagnosed?
To diagnose coronary artery disease, doctors will check the patient’s medical history and any symptoms that may indicate heart problems. They may also perform a physical examination.
Often, they will order an electrocardiogram (ECG) test. An electrocardiogram is a technique that detects changes in voltage over time across the heart, at different angles. When CAD causes enough blockage of blood flow to cause ischemia (insufficient blood supply) in certain parts of the heart, the EKG can show abnormalities in the heart’s activity.
Doctors will also order blood tests. Important blood values include the concentration of LDL cholesterol in a person’s blood and the concentration of triglycerides (fat molecules).
Patients may be referred to a cardiologist for further testing, such as additional ECG testing, ultrasound imaging of the heart (echocardiogram), or evaluation with a wearable heart monitor, which is a version of the ECG that you wear for a few days or Weeks transmits the data to the cardiologist.
Complications of coronary artery disease
Coronary artery disease can lead to a condition called myocardial ischemia in which the artery cannot deliver adequate amounts of blood and oxygen to the heart muscle. This can happen because the artery is gradually becoming clogged with plaque, narrowing the lumen of the artery (the hollow medium through which blood passes) and hardening of the artery wall.
In addition, an atherosclerotic artery that has not been blocked enough to cause ischemia can suddenly become blocked by a piece of plaque that breaks off and swells by triggering the clotting process. In general, this would lead to ACS.
Even without rupture of the plaques, the gradual increase in blockage caused by atherosclerosis disrupts a person’s ability to perform physical activities, such as walking up stairs or around a block.
When doctors suspect that a patient’s coronary heart disease may be causing life-threatening heart problems, such as ACS, myocarditis (inflammation of the muscle tissue of the heart) or pericarditis (inflammation of the sac surrounding the heart), the blood is tested to see if levels of certain enzymes are elevated, Including a group of enzymes called troponins. Troponin is measured as it leaks from heart muscle tissue when it is damaged.
In cases of ACS, clinicians can use troponin measurements and ECGs to distinguish between broad subtypes of ACS, which has important implications for treatment and further testing. In cases where either heart failure or myocarditis is suspected, they will also check blood for levels of brain natriuretic peptide (BNP), a hormone that enters the blood when the heart is under stress.
Treatment of coronary artery disease
Treatment for CAD usually involves a combination of medication and lifestyle changes.
Medications can include cholesterol-lowering drugs, aspirin (to make it more difficult for platelets to stick to each other and to the walls of blood vessels to form clots), drugs to slow the heart as it increases the strength of each contraction, or drugs to widen blood vessels and/or to lower blood pressure.
Lifestyle changes can also help reduce a patient’s risk of coronary heart disease and related health problems. According to the Cleveland Clinic (Opens in a new tab)These include quitting smoking, reducing alcohol use, maintaining a healthy weight, limiting foods high in saturated fat, sodium and sugar, and getting enough sleep.