Coronary artery disease (CAD) is a common form of heart disease and is a major cause of illness and death. Screening tests to detect signs of CAD before serious medical events occur are therefore of particular importance for patients with risk factors for CAD.
What are the initial tests for coronary heart disease?
The first test for CAD commonly involves stressing the heart under controlled conditions. These tests, known as stress tests are able to detect the presence of flow-limiting blockages in the coronary arteries, generally in the range of at least a 50 percent reduction in the diameter of at least one of the three major coronary arteries.
There are two basic types of stress tests; those that involve exercising the patient to stress the heart (exercise cardiac stress tests), and those that involve chemically stimulating the heart directly to mimic the stress of exercise (physiologic stress testing). Physiologic stress testing can be used for patients who are unable to exercise.
Some of the non-invasive tests that are performed are
• Resting electrocardiogram (ECG or EKG)
• Signal-averaged electrocardiogram (SAECG)
• Chest X-ray
• Holter monitor (ambulatory electrocardiogram)
• Echocardiogram
• Exercise stress test
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Magnetic resonance angiography (MRA)
Which are the common tests?
Electrocardiogram (EKG) -An EKG is a recording of the electrical activity of the heart. It can help to detect abnormalities in heart rate and rhythm and it can also give information about whether or not the heart muscle is receiving enough oxygen and blood.
Stress Test- a stress test is performed on a treadmill and evaluates the heart and blood pressure's response to exercise. During a stress test, the individual is connected to a heart and blood pressure monitor, while their level of physical activity is slowly increased. Changes in the EKG during this exam can identify stress-related abnormalities of the heart muscle that might not be evident on a resting electrocardiogram.
Nuclear scanning- a nuclear scan is sometimes used to evaluate the heart's ability to pump blood and to show damaged areas of the heart muscle. This test involves the injection of a small amount of radioactive material (usually injected into an arm vein). After the dye has been taken up by the heart muscle, a special camera is used to scan the heart and detect areas of unhealthy tissue.
Coronary Angiogram- A coronary angiogram or cardiac catherization is considered the most accurate method for diagnosing the severity of coronary artery disease. This procedure involves the insertion of a long, thin catheter (usually inserted through the forearm or groin) which is tunneled into the heart's circulatory system. Dye is then injected into the catheter, to show the flow of blood within the coronary arteries. Narrowed areas and blockages in the arteries can be detected.
What are the other tests?
There are other tests which fall under the invasive- category. These are:
- Nuclear imaging (each requires a needle puncture in an arm vein)
- MUGA scan
- Thallium stress test
- SPECT test
- PET test
Other imaging tests
- Transesophageal echocardiogram (T.E.E.)
- Cardiac catheterization ("cath") - also known as coronary angiography
Which test is the most effective?
A Coronary angiography is used to identify the exact location and severity of CAD and is considered the most effective one.
Angiographic images accurately reveal the extent and severity of all coronary arterial blockages. In appropriate patients, the therapeutic information learned from the angiogram is far more valuable than the relatively small risk of the procedure. For patients with severe angina or myocardial infarction, or those who have markedly abnormal noninvasive tests for CAD, the angiogram also helps the doctor select the optimal treatment, which may include medications, balloon angioplasty, coronary stenting, atherectomy ("roto-rooter"), or coronary bypass surgery. The coronary angiogram is the only test which allows the precise quantification of the extent and severity of CAD to optimally make these treatment decisions.
The diagnosis of coronary heart disease is made based on family and patient history, physical examination, symptoms, and the results of diagnostic testing. Many times, coronary heart disease produces few if any symptoms. For this reason, it is important for all adults to have regular examinations by a physician, which should include not only a physical exam but also a medical screening to evaluate your overall risk factors for heart disease.
