Heart attacks can come on without warning, even in a person who appears fit and never had symptoms. The process of coronary artery disease (CAD), which leads to heart attacks, is complex and usually starts early in life. Over a period of years, plaques that accumulate within artery walls narrow passageways and restrict blood supply to the heart. The earlier the signs of heart disease are spotted, the greater the chance of preventing a heart attack.
The first step
Most people should be screened for heart disease at a routine physical exam. During this exam, your doctor will listen to your heart and certain blood vessels (the carotid and femoral arteries) with a stethoscope and check your pulse, respiration, and blood pressure. You will also receive tests for blood cholesterol (total, LDL, and HDL), triglycerides, and blood sugar. Additional blood tests may be useful in some cases. At your exam, your doctor will ask if you’ve ever had any cardiac symptoms, such as shortness of breath or chest pain. You also will provide information about your family history of heart disease (do you have a parent or sibling who had a stroke or heart attack before age 55, if a man, or before 65, if a woman?) and discuss your habits (do you smoke, have you gained a lot of weight, do you exercise, how healthy is your diet?).
Depending on your coronary risk factors and symptoms, if any, your doctor may recommend further tests. Here’s a rundown of some more common ones, from simple to high-tech, which might be advised under different circumstances.
Electrocardiogram (ECG or EKG). This fast, painless test records the heart’s electrical activity through small electrodes placed on your body. It is not usually part of the routine physical exam for healthy people but may be done if you have symptoms or certain risk factors. It can detect a heart attack (past or present) or be used to diagnose other problems, such as abnormal heart rhythms or enlarged heart chambers. A Holter monitor allows for continuous ECG monitoring, via a small recorder and electrodes that you wear under your clothing for 24 hours (or longer). An event monitor, typically worn for several weeks, records heart activity only when you feel symptoms and push a button.
Exercise stress test. Also known as a treadmill test, it can show how much stress your heart can tolerate before problems develop, such as abnormal blood pressure, an irregular heart rhythm, or chest pain. The test consists of walking on a treadmill or riding a stationary bike while being continously monitored with an ECG and having your blood pressure taken at regular intervals. The effort (speed or resistance) is gradually increased according to a standard protocol; you also regularly report your level of perceived exertion and whether or not you’re experiencing any symptoms. Because you are exerting yourself, the effects of coronary artery narrowing are more likely to show up than in a regular ECG. Stress tests thus carry a slight risk and must be closely monitored by a physician or technician.
Echocardiogram. A device called a transducer beams ultrasound waves at your heart, and the returning echoes are used to create a picture of the heart and its moving valves. If a “color Doppler” is used, blood flow through the heart can also be evaluated. There are several kinds of echocardiograms, including a stress echocardiogram, done immediately after a treadmill workout, which can reveal abnormal heart contraction patterns.
Myocardial perfusion scan. This nuclear imaging test evaluates blood flow to the heart. A small amount of radioactive material is injected in a vein, and then a special camera captures images as the substance passes through your heart and arteries. The test usually consists of two parts: one at rest and one after exercise (or a drug may be given that has a similar effect on the heart as does exercise), and the images are compared. In a heart free of blockages, there should be little difference at rest and after exercise.
Electron-beam computed tomography (EBCT). This imaging procedure detects calcium deposits in coronary arteries, which may signal the presence of CAD. Studies have found that the higher the amount of calcium, the higher the risk of heart attacks. EBCT may be helpful for people at intermediate risk for a heart attack when trying to decide whether or not to start statin therapy. The test is not without risk, however, as it exposes the individual to radiation, though the dose is low.
Computed tomography angiography (CTA). Also referred to as multidetector scanning, this rapidly developing imaging technology produces high-resolution, three-dimensional computerized pictures of the moving heart and large blood vessels that reveal the extent and nature of plaque formation or calcium deposits. Contrast material may be injected in a vein to improve the quality of the images. Newer systems produce better images much faster—and with less radiation.
Coronary magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA). This test uses magnetic fields and computers to produce images of the heart and arteries. It can detect valve problems, heart enlargement and vessel disease as well as damaged heart tissue and other abnormalities. Contrast material may be injected. An advantage is that it detects CAD without radiation and is not invasive. Although relatively new and expensive, it may turn out to be the preferred way to visualize the coronary arteries and may one day be useful in diagnosing people who come to the emergency room with chest pain.
Coronary angiogram. This procedure typically involves inserting a catheter into the femoral artery in the groin area; the catheter is then guided to the coronary arteries. Contrast material is injected that allows x-rays to be used to observe the heart, arteries, and valves at work. Angiography is the gold standard for diagnosing CAD, but because it is invasive and involves some risks, it is done primarily in people who are candidates for coronary angioplasty (a procedure done to reopen a blocked artery) or bypass surgery.
Also see 13 Tips for Preventing Heart Disease.