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.
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
-
-
-
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:
-
-
-
-
Angina unrelieved by rest or nitroglycerin, severe angina, agina 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; allows the doctor to look for abnormalities in the arteries. This can be done invasively 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:
-
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 the heart artery to push 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 called restenosis.
-
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.
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.
RESOURCES:
American Heart Association
http://www.americanheart.org
National Heart, Lung, and Blood Institute
http://www.nhlbi.nih.gov
References:
American Heart Association website. Available at: http://www.americanheart.org.
Arora RR, Chou TM et al. The multicenter study of enhanced external counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes.J Am Coll Cardiol. 1999;33(7):1833-1840.
Braunwald’s Heart Disease, 7th ed. 2004.
Griffith's 5-Minute Clinical Consult. Lippincott Williams & Wilkins; 2001.
Hurst's The Heart. 11th ed. 2004.
National Heart, Lung, and Blood Institute website. Available at: http://www.nhlbi.nih.gov.
