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Coronary Artery Disease (CAD)

Coronary artery disease (CAD) is one of the most common forms of heart disease and a leading cause of death of both men and women in Canada. The dominant effect of coronary artery disease (CAD) is the loss of oxygen and nutrients to myocardial tissue because of diminished coronary blood flow. This disease is near epidemic in the Western world.

Causes

Both men and women can get CAD. It can be hereditary (run in your family). It might also develop as you get older and plaque builds up in your arteries over the years. You may get CAD if you are overweight or if you have high blood pressure or diabetes. High cholesterol may also lead to CAD . CAD can stem from making unhealthy choices such as smoking, eating a high-fat diet and not exercising enough.

Uncommon causes of reduced coronary artery blood flow include dissecting aneurysms, infectious vasculitis, syphilis, and congenital defects in the coronary vascular system. Coronary artery spasms may also impede blood flow.

Signs and symptoms

The classic symptom of CAD is angina, the direct result of inadequate flow of oxygen to the myocardium. It's usually described as a burning, squeezing, or tight feeling in the substernal or precordial chest that may radiate to the left arm, neck, jaw, or shoulder blade.

Typically, the patient clenches his fist over his chest or rubs his left arm when describing the pain, which may be accompanied by nausea, vomiting, fainting, sweating, and cool extremities. Anginal episodes most often follow physical exertion but may also follow emotional excitement, exposure to cold, or a large meal.

Angina has three major forms:

• Stable angina causes pain that's predictable in frequency and duration and can be relieved with nitrates and rest.
• Unstable angina causes pain that increases in frequency and duration. It's more easily induced.
• Prinzmetal's angina causes unpredictable coronary artery spasm.

Severe and prolonged anginal pain generally suggests MI, with potentially fatal arrhythmias and mechanical failure.

Diagnosis

• Electrocardiography (ECG) during angina may show ischemia or may be normal; it may also show arrhythmias, such as premature ventricular contractions. The ECG is apt to be normal when the patient is pain-free.
• Treadmill or bicycle exercise test may provoke chest pain and ECG signs of myocardial ischemia (ST-segment depression).
• Coronary angiography reveals narrowing or occlusion of the coronary artery, with possible collateral circulation.
• Myocardial perfusion imaging with thallium-201 or cardiolite during treadmill exercise detects ischemic areas of the myocardium, visualized as "cold spots."

Treatment

The goal of treatment in patients with angina is to either reduce myocardial oxygen demand or increase oxygen supply. Therapy consists primarily of nitrates, such as nitroglycerin (given sublingually, orally, transdermally, or topically in ointment form), isosorbide dinitrate (given sublingually or orally), beta-adrenergic blockers (given orally), or calcium channel blockers (given orally). Obstructive lesions may necessitate coronary artery bypass surgery and the use of vein grafts.

Angioplasty may be performed during cardiac catheterization to compress fatty deposits and relieve occlusion in patients with no calcification and partial occlusion. A certain risk is associated with this procedure, but its morbidity is lower than that for surgery. Percutaneous transluminal coronary angioplasty may be done in combination with coronary stenting. Stents provide a framework to hold an artery open by securing flaps of tunica media and intima against the artery wall.

Lifestyle changes

Although great advances have been made in treating coronary artery disease, changing your habits remains the single most effective way to stop the disease from progressing. Here are the most beneficial changes you can make:

• Don't smoke. Smoking is a major risk factor for coronary artery disease. Quitting smoking dramatically lowers your risk of a first or second heart attack.
• Exercise regularly.
• Eating less fat should also help you lose weight. If you're overweight, losing weight can help you further lower blood cholesterol. Eating a diet rich in fruits and vegetables and having at least one to two servings of fish a week also can reduce your risk of a heart attack.

Prevention

Because CAD is so widespread, prevention is of incalculable importance. Dietary restrictions aimed at reducing intake of calories (in obesity) and of dietary fats and cholesterol serve to minimize the risk, especially when supplemented with regular exercise. Abstention from smoking and reduction of stress are also beneficial.

Other preventive actions include control of hypertension (with sympathetic blocking agents, such as methyldopa and propranolol, or diuretics, such as hydrochlorothiazide), control of elevated serum cholesterol or triglyceride levels (with antilipemics, such as HMG-reductase inhibitors like cerivastatin sodium (Baycol), atorvastatin calcium (Lipitor), pravastatin sodium (Pravachol), or simvastatin (Zocor), and measures to minimize platelet aggregation and the danger of blood clots (with aspirin).