Angina: A Patient Guide

A first step is an electrocardiogram or ECG. When the heart is not getting enough blood, the electrical waveforms of the ECG can show characteristic changes from normal that may help make a diagnosis. The limitations of ECG are that heart problems other than CAD can cause changes in the waveforms, and that even when a person is having angina or a heart attack, the ECG may be completely normal. Timing is also important. If the ECG is done at a time when a person feels no symptoms and the blood flow is adequate, it may not reflect what happens when decreased blood flow occurs.

This last limitation is reduced when an ECG is done during exertion or exercise. This is the basis for an exercise treadmill test (ETT), sometimes called a “stress test.”  The exercise causes an increased need for blood that the diseased vessels cannot provide, and therefore the ECG may become abnormal. The patient may also experience angina symptoms during exercise. Unfortunately, the ETT is not perfect and, for a variety of reasons, may be incorrectly positive or negative up to 35% of the time.

The limitations of the ETT can be reduced, however, by adding an echocardiogram or radioisotopic imaging to the process. This is called a stress echocardiogram study (“stress echo”) or stress imaging (usual radioisotopes include thallium 201 or technetium 99m). Using a sophisticated computer and monitor and a plastic probe and some gel on the chest, the echocardiogram can look directly at the movements of the heart with each beat. It has been shown that when the heart isn’t getting enough blood, the walls of the heart move in a manner describes as dyssynchronous. There are several patterns of irregularity of varying severity. This “wall motion abnormality,” as it is called, can happen before the ECG is abnormal and before a person develops chest pain or other angina symptoms. Though it provides increased accuracy for the diagnosis of CAD and angina, it, too, is not 100% accurate.

Radioisotopic imaging is accomplished when an isotope is injected through an IV line during a period of exercise. By comparing pictures of the heart (created by radiation emitted from the radioisotope) during and after exercise, areas of decreased blood flow or prior heart damage can be identified. Though it is more accurate, the stress thallium study takes more time than the other stress tests, is more expensive, and involves an IV and some radiation (though not much).

With any stress test, an adequate level of exercise is extremely important for the accuracy of the study. This is calculated based on the person’s age, heart rate and blood pressure with exertion. Stress testing demonstrates what happens with exercise, and in the “recovery period” after exercise (this can be important as well). During this period, irregular heart rhythms or a slower than expected return to normal heart rate can indicate a poor prognosis.

If a person cannot exercise adequately – due to age, arthritis, poor conditioning, or lung problems, for example – then activity can be simulated by a continuous IV injection of a medication called dobutamine. This causes the heart rate and blood pressure to increase without having to exercise and is used mostly in conjunction with the stress echo. An alternative to dobutamine for the thallium study is a continuous injection of a medication called dipyridamole that causes unblocked coronary arteries to widen while those that have significant blockages cannot. The differences between the areas of the heart supplied by the blocked and unblocked vessels can then be seen on the thallium pictures.

The most accurate test or gold standard for the evaluation of CAD and angina is an angiogram or cardiac catheterization. This is, however, the most expensive and invasive of the tests and is therefore used only when absolutely necessary. An angiogram involves the use of a significant, though safe, amount of radiation (x-rays), and is the most difficult to perform and most risky of the tests addressed in this article. In trained hands, however, the risk of complications is less than 1-2%. The angiogram procedure involves threading a catheter, or thin plastic tube, from a blood vessel in the groin or in the arm up into the aorta, the major blood vessel going from the heart to the body. The openings for the coronary arteries are in this location and contrast dye is injected through the catheter into them. X-rays are used to show the arteries and any blockages. Laying out the pattern and extent of diseased vessels with an angiogram is necessary prior to angioplasty or bypass surgery.

A developing technology for evaluating some patients with CAD is magnetic resonance angiography, or MRA. By using the same MRI technology that’s used more commonly to look at the brain, spine, or joints, some significant coronary artery blockages can be seen. There are limitations to this study, but it may be an alternative in some cases.

Another CAD test that has received getting media attention is the electron beam CT scan (EBCT). This type of “heart scan” is often offered in a shopping mall setting, either by itself or as part of a “total body scan.” This technology uses some radiation, but is appealing because it does not involve needles, exercise, or apparent risk. It works by detecting tiny calcium deposits in the lining of the coronary arteries. In some situations, this has allowed people to know they have potentially significant CAD before they have symptoms. In other situations, there are calcium deposits but no significant narrowing of the arteries, and the abnormal EBCT results have led to further testing which has proven to be unnecessary. In other situations, there may be significant artery narrowing without calcium deposits and so the EBCT results may be falsely reassuring. Given these limitations, the exact usefulness of EBCT has yet to be determined. Given the limited information that is given by the test it is doubtful that it will continue to emerge as a needed diagnostic tool. The newer 64 slice CT scanners are able to show a large portion of the coronary arterial tree when the same angiographic contrast media (dye) use at coronary angiography is given. Unfortunately, although good images are attained, the radiation from this test is currently higher than that of cardiac catheterization with coronary angiography.

Laboratory blood tests have a use in the evaluation of patients with angina, but only in certain instances. Patients with possible unstable angina or heart attack are evaluated with blood tests in the emergency department or hospital. Heart enzymes (like creatine phosphokinase or CPK) and proteins (like myoglobin and troponins) can be measured in the blood in situations of prolonged or unstable symptoms, to determine whether heart damage has occurred. Blood tests are also useful in determining or monitoring a person’s risk factors for CAD, like cholesterol, diabetes, or homocysteine. Unfortunately, unless someone is having a heart attack, no blood tests can tell definitely whether or not a person has CAD.

How is angina treated?

Those with risk factors for CAD such as diabetes, high blood pressure, and high blood cholesterol levels should control them with lifestyle modifications (exercise, controlling body weight, and an appropriate diet) and medications (there are many).

Even for those without these risk factors, everyone with angina or at risk for CAD should make lifestyle modifications to reduce and sometimes reverse the development of CAD. This includes quitting any smoking or drug use, eating a diet low in cholesterol and saturated fat, exercising regularly, and maintaining a lean body weight.

Many medications can help reduce the symptoms of angina. Medications used for stable angina include nitroglycerine (short- and long-acting), beta blockers, and calcium channel blockers, all of which help to balance the heart’s supply and demand for blood. ACE-inhibitors reduce the risk of heart attack in those with CAD. Aspirin is very helpful in reducing the chance of clot formation and heart attack, and it and several other medications may help by reducing inflammation within the plaques.

A supervised exercise program, cardiac rehabilitation, can help increase exercise tolerance in those with CAD, especially after a heart attack or a heart procedure like angioplasty or bypass surgery.

Beyond medications, there are three procedures that directly improve blood flow to the heart:

• Angioplasty
• Coronary artery bypass grafting (abbreviated CAB or CABG)
• Enhanced external counter-pulsation (EECP)

Choosing which procedure is best depends on a particular patient’s overall condition as well as the severity and distribution of coronary artery blockages. Angioplasty (also known by the abbreviation PTCA, for Percutaneous Transluminal Coronary Angioplasty) can be done immediately following an angiogram or at a later date. The procedure involves passing a small balloon catheter across the artery blockage and inflating it; most of the time the blockage will then stay open. In addition, a small wire-mesh scaffolding, called a stent, may be left behind within the blockage to minimize the chance of reclosure.

Coronary artery bypass surgery is a major surgical procedure involving stitching vein or artery sections from the aorta onto the coronary arteries, beyond the blockages. This restores blood-flow to previously deprived areas of the heart. The original technique is performed with the heart completely stopped and the blood flow to the brain and body maintained by a cardiopulmonary bypass machine. The newer off-pump coronary artery bypass method (OP-CAB) is possible for some patients. With OP-CAB, the cardiopulmonary bypass machine is not needed and the risk of stroke may therefore be reduced. As a result, the heart can recover faster because its beating was not stopped for the surgery. For those with limited blockages in certain locations on the heart, a minimally invasive procedure (MIDCAB) may be possible.

Angioplasty, angioplasty with stenting, or any method of bypass surgery may also be performed electively in those with stable angina who are determined to be in need of surgery. For those with unstable angina, any of these may need to be performed on an emergency basis

Enhanced external counter-pulsation (EECP) is a technique for improving blood flow to the heart without involving surgery. It involves 35 hour-long sessions once or twice a day in which cuffs (like large blood pressure cuffs) are inflated and deflated on both legs in synchronization with the heartbeat. Over the course of treatment, the pattern of blood flow to the heart may change, providing benefit and decreasing angina symptoms even for many months after the treatment has ended.

Where can I learn more about angina?

You can learn more about the causes, symptoms, and treatment of angina and coronary artery disease by using these as search terms on MyHeartCentral.com. The American Heart Association (www.americanheart.org), American College of Cardiology (www.acc.org) and National Heart, Lung, and Blood Institute (www.nhlbi.nih.gov) have information available on their websites as well.

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