Definition

Coronary artery disease (CAD) is blockage of the arteries that feed the heart muscle. If the blockage is complete, areas of the heart muscle may be damaged and/or die from lack of oxygen. This can lead to a heart attack, otherwise known as a myocardial infarction .

Coronary artery disease is the most common form of heart disease and is the leading cause of death in the United States and worldwide.

Coronary Artery Disease

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Causes

Causes include:

  • Thickening of the walls of the arteries feeding the heart muscle
  • Accumulation of fatty plaques within the coronary arteries
  • Sudden spasm of a coronary artery
  • Narrowing of the coronary arteries
  • Inflammation within the coronary arteries
  • Development of a blood clot within the coronary arteries that blocks blood flow
    • Clot formation at the site of a narrowed artery (rather than progressive arterial narrowing to the point of blockage) is the precipitating cause of CAD events.
    • Clots may also occur silently without a clinical event and lead to progressive plaque enlargement and further narrowing of the artery.
  • There has also been debate about the role of infection (by Chlamydia pneumoniae ) in causing CAD. But trials of antibiotics targeting this infection showed no evidence of an effect on CAD.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Major risk factors include:

  • Sex: male (men have a greater risk of heart attack than women)
  • Age: 45 and older for men, 55 and older for women
  • Heredity: strong family history of heart disease
  • Obesity and being overweight
  • Smoking
  • High blood pressure
  • Sedentary lifestyle
  • High blood cholesterol (specifically, high LDL cholesterol, and low HDL cholesterol)
  • Diabetes

Other risk factors include:

Symptoms

CAD may progress without any noticeable symptoms.

Symptoms include:

  • Angina —intermittent chest pain that often has a squeezing or pressure-like quality, that may radiate into the shoulder(s), arm(s), or jaw. Angina usually lasts for about 2-10 minutes and is often relieved with rest. Angina can be triggered by:
    • Exercise or exertion
    • Emotional stress
    • Cold weather
    • A large meal

Angina unrelieved by rest or nitroglycerin, severe angina, angina that begins at rest (with no activity), or angina that lasts more than 15 minutes are warning signs of unstable angina or a heart attack. Accompanying symptoms may include:

  • Shortness of breath
  • Sweating
  • Nausea
  • Weakness

Immediate medical attention is needed for unstable angina.

CAD in women may cause less classic chest pain and be heralded by shortness of breath on exertion and fatigue.

Diagnosis

If you go to the emergency room with chest pain, some tests will be done right away to see if you are having an episode of angina or a heart attack. If you have a stable pattern of angina, other tests may be done more electively to determine the severity and extent of your disease and to create a treatment plan.

The doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include:

  • Blood tests—to look for certain substances in the blood called troponins which help the doctor determine if you are having an acute heart attack
  • Electrocardiogram (ECG, EKG)— records the heart's activity by measuring electrical currents through the heart muscle, and can reveal evidence of past heart attacks, acute heart attacks, and heart rhythm problems
  • Echocardiogram —uses high-frequency sound waves (ultrasound) to examine the size, shape, and motion of the heart, giving information about the structure and function of the heart
  • Exercise stress test —records the heart's electrical activity during increased physical activity
  • Nuclear stress test—radioactive material is injected into a vein during exercise or pharmacologic stress and observed as it is absorbed by the heart muscle. This can help tell your doctor whether there is impaired blood flow suggesting an obstructed coronary artery.
  • Coronary calcium scoring—a type of x-ray called a CAT scan that uses a computer to make pictures of the heart. The presence of calcium in the heart arteries suggests that atherosclerosis or hardening of the arteries is occurring
  • Coronary angiography — x-rays taken after a dye is injected into the arteries to allows the doctor to look for abnormalities in the arteries. This can be done through a puncture into the large artery in the groin or noninvasively with new CAT Scan technology.

Treatment

Treatment may include:

Nitrate Medications

Nitroglycerin is usually given during an acute attack of angina. It can be given as a tablet that dissolves under the tongue or as a spray. There are also longer-lasting types that can be used to prevent angina before you participate in an activity known to cause it. These may be given as pills or applied as patches or ointments.

Blood-Thinning Medications

A small, daily dose of aspirin has been shown to decrease the risk of heart attack. Ask your doctor before taking aspirin daily. Warfarin (Coumadin), ticlopidine (Ticlid), and clopidogrel (Plavix) are also used for some patients.

Beta-Blockers, Calcium-Channel Blockers, and ACE-Inhibitors

These may help prevent angina and, in some cases, lower the risk of heart attack.

Medications to Lower Cholesterol

These medication may prevent the progression of coronary artery disease and may even improve existing coronary artery disease.

Evidence shows that lowering cholesterol has a positive effect on prevention of CAD events.

Revascularization

Patients with severe blockages in their coronary arteries may benefit from procedures to improve blood flow to the heart muscle:

  • Percutaneous coronary interventions (PCI)—catheter-based procedures done through a small puncture into the large artery in the groin. These include balloon angioplasty where a small balloon is inflated in a coronary artery to widen and compress plaque out of the way. In some cases, a wire mesh stent is placed to hold the artery open. Some newer stents are coated with a medication (drug eluting stents) to prevent recurrent narrowing due to clot formations.
  • Coronary artery bypass grafting (CABG) —done surgically through an incision in the chest. Segments of arteries taken from the chest wall and wrist or veins taken from the legs are sewn into the heart arteries to reroute blood flow around blockages.

According to a review of 23 studies, patients who received CABG had more angina relief and less need for another, similar procedure than those who received PCI. * 2

Another study compared PCI plus optimal medical therapy (intensive medications and lifestyle changes) to optimal medical therapy alone in stable heart patients. Researchers found that adding PCI to treatment did not reduce the risk of death, myocardial infarction, or other heart-related events. * 1

Options for Refractory Angina

For patients who are not candidates for revascularization procedures but have continued angina despite medication, options include:

  • Enhanced external counterpulsation (EECP)—large air bags like blood pressure cuffs are inflated around the legs in sequence with the patient’s heart beat. The patient receives 5 one-hour treatments per week for seven weeks. This has been shown to reduce angina frequency and may improve symptom-free exercise duration.
  • Transmyocardial revascularization (TMR)—surgical procedure done with laser to reduce chest pain
  • Researchers are also studying gene therapy as a possible treatment.

Prevention

To reduce your risk of getting coronary artery disease:

  • Maintain a healthy weight.
  • Begin a safe exercise program with the advice of your doctor.
  • If you smoke, quit.
  • Eat a healthful diet, low in saturated fat and rich in whole grains, fruits, and vegetables.
  • Treat your high blood pressure and/or diabetes.
  • Treat high cholesterol or triglycerides.