Coronary artery disease is the narrowing or blockage of the coronary arteries, usually caused by atherosclerosis. Atherosclerosis (sometimes called “hardening” or “clogging” of the arteries) is the buildup of cholesterol and fatty deposits (called plaques) on the inner walls of the arteries. These plaques can restrict blood flow to the heart muscle by physically clogging the artery or by causing abnormal artery tone and function.
Without an adequate blood supply, the heart becomes starved of oxygen and the vital nutrients it needs to work properly. This can cause chest pain, which is called angina. If blood supply to a portion of the heart muscle is cut off entirely, or if the energy demands of the heart become much greater than its blood supply, a heart attack (injury to the heart muscle) may occur.
Coronary artery disease starts when you are very young. Before your teen years, the blood vessel walls begin to show streaks of fat. As you get older, the fat builds up, causing slight injury to your blood vessel walls. Other substances traveling through your blood stream, such as inflammatory cells, cellular waste products, proteins and calcium begin to stick to the vessel walls. The fat and other substances combine to form a material called plaque.
Over time, the inside of the arteries develop plaques of different sizes. Many of the plaque deposits are soft on the inside with a hard fibrous “cap” covering the outside. If the hard surface cracks or tears, the soft, fatty inside is exposed. Platelets (disc-shaped particles in the blood that aid clotting) come to the area, and blood clots form around the plaque. The endothelium can also become irritated and fail to function properly, causing the muscular artery to squeeze at inappropriate times. This causes the artery to narrow even more.
Sometimes, the blood clot breaks apart, and blood supply is restored. In other cases, the blood clot (coronary thrombus) may suddenly block the blood supply to the heart muscle (coronary occlusion), causing one of three serious conditions, called acute coronary syndromes.
What are Acute Coronary Syndromes?
Unstable angina: This may be a new symptom or a change from stable angina. The angina may occur more frequently, occur more easily at rest, feel more severe, or last longer. Although this can often be relieved with oral medications (such as nitroglycerin), it is unstable and may progress to a heart attack. Usually more intense medical treatment or a procedure are required to treat unstable angina.
Non-ST segment elevation myocardial infarction (NSTEMI): This type of heart attack, or MI, does not cause major changes on an electrocardiogram (ECG). However, chemical markers in the blood indicate that damage has occurred to the heart muscle. In NSTEMI, the blockage may be partial or temporary, so the extent of the damage is usually relatively small.
ST segment elevation myocardial infarction (STEMI): This type of heart attack, or MI, is caused by a sudden blockage in blood supply. It affects a large area of the heart muscle, and causes changes on the ECG as well as in blood levels of key chemical markers.
Although some people have symptoms that indicate they may soon develop an acute coronary syndrome, some may have no symptoms until something happens, and still others have no symptoms of the acute coronary syndrome at all.
All acute coronary syndromes require emergency evaluation and treatment.
How did I get coronary artery disease?
Heart disease is the leading cause of death among men and women in the United States. Risk factors for coronary artery disease are modifiable or non-modifiable and include the following:
- Male gender
- Advanced age, especially after the age of 65
- Family history of heart disease, especially if diagnosed before the age of 50
- Race- higher risk is associated with African Americans, Mexican Americans, American Indians, native Hawaiians and some Asian Americans
- Cigarette smoking and tobacco exposure
- High blood pressure (140/90 mmHg or higher)
- Uncontrolled diabetes (HbA1c>7.0)
- High blood cholesterol and high triglycerides (high LDL over 100 mg/dL or low HDL under 40 mg/dL)
- Physical inactivity
- Being overweight (BMI 25-29) or being obese (BMI higher than 30)
- Uncontrolled stress or anger
- Unhealthy diet