Coronary Artery Disease

Overview

Coronary artery disease (CAD) refers to the narrowing of heart arteries due to atherosclerosis (see below). The heart muscle does not get enough oxygen when heart arteries are narrowed. If the heart is starved of oxygen, chest pain (angina) occurs. If an artery is completely blocked, a heart attack results, medically referred to as a myocardial infarction (MI). CAD is the most common form of heart disease and is the number one killer of both men and women.

Many of these deaths can be prevented because some risk factors for CAD are controllable. These controllable factors often are related to lifestyle and include high blood pressure, high blood cholesterol, smoking, obesity, and physical inactivity.

Although medical treatments for heart disease have come a long way, controlling risk factors remains the key to preventing illness and death from CAD.

Causes

A low supply of oxygen in the heart is most often caused by atherosclerosis, also called "hardening of the arteries." In this condition, fatty deposits called plaques form in the linings of the blood vessels. The plaques make the arteries narrower as they build up, and less blood is able to get through to the heart, depriving it of oxygen. Atherosclerosis is often the result of too much "bad" cholesterol (low density lipids and triglycerides) circulating in the blood stream.

You are at risk for developing atherosclerosis and CAD if you:

• have high levels of "bad" cholesterol (either from a high-fat diet, or produced naturally by the liver)
• have high blood pressure
• are a smoker
• have diabetes
• lead a sedentary lifestyle
• are overweight (particularly if you are a man who is obese in the torso)

Occasionally, a genetic condition can cause atherosclerosis, leading to heart disease.

Men run a higher risk of developing the disease than pre-menopausal women. After menopause, the incidence of CAD in women increases, and can be equal to men.

Symptoms

Some people with CAD might have no symptoms until the disease is severe enough to cause chest pains, or angina pectoris (angina comes from the Greek word for "strangling").

Stable angina is often the first sign that a person has CAD. Chest pain or discomfort occurs with activity and is relieved by rest. With unstable angina, symptoms become less predictable and can occur when you are at rest. This indicates rapid progression of CAD and higher risk of a heart attack and requires that you see a doctor immediately.

Some symptoms of angina include:

• tightness or a squeezing sensation across the chest
• burning or pressure beneath the breast bone
• pain or ache radiating to the shoulders, jaw, arms, throat, neck, or upper abdomen
• fatigue
• nausea or vomiting
• sweating
• weakness
• shortness of breath
• lightheadness

If a plaque lining a blood vessel ruptures, it may completely block an area of the heart from receiving the oxygen-rich blood supply it needs. The starved cells in that area will then die, resulting in an MI.

The symptoms of a heart attack are similar to those of angina, but much stronger.

Men will often feel:

• constant pain in the middle of the chest that may radiate to the neck, jaw, left shoulder or arm
• tightness or squeezing in the chest
• a sensation of "heaviness" or heavy indigestion
• sweating, nausea, and vomiting
• shortness of breath

In women, the main symptoms can be similar to men but may also include:

• shoulder, neck, or back pain
• feeling a sharp pain on breathing in cold air
• fatigue

It's very important to get medical help as quickly as possible if you feel you have the symptoms of a heart attack.

Treatment

Your doctor may prescribe any of these medication treatments:

• Cholesterol-lowering medications can reduce the levels of "bad" cholesterol in your blood while increasing the levels of "good" (high-density lipid) cholesterol. Your medication will be chosen based on the ratios of various cholesterol types found in your blood.
• Blood-pressure-reducing agents can lower your risk of heart attack dramatically if you have high blood pressure. These medications come in several types, and your doctor will advise which medication is best for you.
• Acetylsalicylic acid (ASA)* reduces the chances of having a heart attack. Only small doses (often known as a "baby" Aspirin^®) are needed to help prevent a heart attack. If you cannot take ASA, your doctor may recommend other medications.
• The three main classes of medications to treat stable angina are beta-blockers, calcium channel blockers, and nitroglycerin-type drugs. Medications that treat angina help reduce the heart's workload.

Getting medication treatment isn't the only way to combat coronary artery disease. Here are a few heart-healthy tips:

• Quit smoking. If you smoke, this is the most important step to reduce the risk of developing CAD quickly and significantly.
• Eat a healthy diet. It should be low in salt and fat (less than 30% of total calories), and high in fibre, fresh fruits, legumes (beans), nuts, and seeds. Avoid saturated fat, partially hydrogenated vegetable oils, fried foods, and refined carbohydrates. Losing weight can also offset the risks associated with CAD.
• Have your cholesterol levels checked regularly. People with diabetes should have this done every one to three years. Men between the ages of 40 and 70 and women between the ages of 50 and 70 should have their cholesterol levels monitored every five years if they do not have CAD or a history of high cholesterol. Check with your doctor if you haven't had a cholesterol check recently. Depending on your risk factors, your target cholesterol levels will differ.
• Get regular exercise. Along with reducing the chances of having a heart attack, regular physical activity lowers the heart rate, improves cholesterol levels, and helps control high blood pressure. It can also help you lose weight. Consult your doctor before starting an exercise program, especially if you have any other medical conditions.
• Manage your stress levels. This will also benefit those with high blood pressure. As well, it reduces the levels of some hormones that may increase the risk of having a heart attack.

 

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*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol^®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For more information on brand names, speak with your doctor or pharmacist.

Other tips:

An electrocardiogram (ECG) detects abnormal electrical cardiac charges. In someone who has had heart damage, the electrical signals that keep the heart beating change as they pass through damaged tissue. This can be detected and measured.

Stress tests indicate how much oxygen the heart is getting during periods of activity, and can also show if the coronary arteries are too narrow. An exercise tolerance test is performed on a treadmill or a stationary bicycle while hooked up to an ECG. A thallium scan allows imaging of blood flow in the heart during exercise. This involves injecting a very small dose of radioactive substance into the bloodstream, which is followed through the heart by a special camera.

With angina, abnormalities in the ECG may only occur while the person is having an angina attack. Some people have "silent angina," where even an attack brings no symptoms. To detect this, you may be asked to wear a monitor for 24 hours. The ECG tape is analysed for irregularities, and then compared with a detailed diary, in which you record your daily activities and any unusual symptoms.

Coronary angiography (or arteriography) is a test used to explore the coronary arteries. A fine tube (catheter) is put into an artery of an arm or leg and passed through the tube into the arteries of the heart. The heart and blood vessels are injected with contrast which is then filmed with an X-ray while the heart pumps. The picture that is seen, called an angiogram or arteriogram, will show problems such as a narrowing or blockage caused by atherosclerosis.

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