The goals of testing for heart disease are to distinguish between symptoms that are heart-related and those that are due to another condition. Testing is ordered to help determine which heart disease is present, to determine whether the disorder is acute or chronic, to monitor a cardiac event that is in progress such as a heart attack, and to determine the severity and extent of the disease.
Heart disease that is causing few symptoms may be detected during a visit to a health practitioner for nonspecific symptoms such as fatigue. The healthcare provider may order a variety of blood and other tests to investigate possible causes of the person's symptoms.
Laboratory blood tests
Screening for risk of cardiovascular disease
Cardiac risk testing is performed to screen asymptomatic people to help determine their risk of developing coronary heart disease. A cardiac risk assessment is a group of tests and health factors that have been proven to indicate the chance of having a cardiovascular event such as heart attack or stroke. The factors considered include age, family history of heart disease, diet, physical activity, and blood pressure, for example. Laboratory tests may include:
- Lipid profile (LDL-C,HDL-C, cholesterol, triglycerides)—a group of tests that examine the amount and type of lipids (fats) in the blood
- hs-CRP—detects low concentrations of C-reactive protein, a marker of inflammation that is associated with atherosclerosis, among other conditions
- Lp(a)—an additional lipid test that may be used to identify an elevated level of lipoprotein (a), a modification to LDL-C that increases risk of atherosclerosis; the test may be used in conjunction with a routine lipid profile to provide additional information.
Several other tests are being studied as potential markers for heart disease. See the article on Cardiac Risk Assessment for more on these.
Diagnosing heart attacks
When someone presents to the emergency room with a possible heart attack (acute coronary syndrome, ACS), the person is evaluated with a variety of laboratory blood tests and other tests, such as imaging procedures (see below). These are used to determine the cause of the pain and the severity of the condition. Since some treatments for a heart attack must be given within a short period of time to minimize heart damage, an accurate diagnosis must be quickly confirmed.
Tests for proteins that are released when muscle cells are damaged, often called cardiac biomarkers, are frequently ordered when someone has symptoms of acute coronary syndrome (ACS), such as chest pain, pain in the jaw, neck, abdomen, back, or that radiates to the shoulder or arms, nausea, shortness of breath, and lightheadedness.
- Troponin—the most commonly ordered and cardiac-specific of the markers; will be elevated within a few hours of heart damage and remain elevated for up to two weeks
- CK-MB—one particular form of the enzyme creatine kinase that is found mostly in heart muscle and rises when there is damage to the heart muscle cells; this test has largely been replaced with the troponin test.
- BNP or NT-proBNP—released by the body as a natural response to heart failure; increased levels of BNP, while not diagnostic for a heart attack, indicate an increased risk of cardiac complications in persons with ACS.
Tests for other heart diseases
- BNP—because BNP is also released by the heart when it is stretched, BNP is also measured in those who have swelling of the legs or abdomen or shortness of breath to assist in diagnosis of heart failure.
- Pericardial fluid analysis—by analyzing the fluid in the sac that surrounds the heart, health practitioners may be able to tell if the heart tissues are inflamed or have been damaged by trauma or infection or whether congestive heart failure has caused fluid to accumulate around the heart
- Blood culture—may be done to identify infection of the heart (endocarditis)
More general blood tests that may be ordered include:
- hs-CRP—may be used to help determine prognosis, including probability of recurrence of cardiac events in those with stable coronary heart disease or ACS
- Blood gases—performed to evaluate oxygen, carbon dioxide, and pH levels
- Comprehensive metabolic panel (CMP)—a group of tests used to evaluate organ function
- Electrolytes—four tests that evaluate the body’s fluid and salt balance
- Complete blood count (CBC)—evaluates blood cells; checks for anemia and infections
A range of other evaluations and tests are used to assess chest pain and other symptoms. These include:
- A medical history, including an evaluation of risk factors such as age, weight, diabetes, and smoking
- A physical examination
- An electrocardiogram (ECG or EKG)—a test that looks at the heart's electrical activity and rhythm
- Echocardiography—ultrasound imaging of the heart
Based on the findings of these tests, other procedures may be necessary, including:
- Stress testing (See a description on the Mayo Clinic website)
- Chest X-ray
- CT (computerized tomography) scan
- Continuous ECG monitoring (sometimes also called Holter monitoring)—the person being tested wears a monitor that evaluates heart rhythm over a period of time.
- MRI (magnetic resonance imaging)
- PET (positron emission tomography)
- Radionuclide imaging
- Cardiac catheterization—in this procedure, a thin flexible tube is inserted into an artery in the leg and threaded up to the coronary arteries to evaluate blood flow and pressure in the heart and the status of the arteries in the heart.
- Coronary angiography—X-rays of arteries using a radiopaque dye to help diagnose CAD; this procedure is performed during coronary catheterization.
- Tilt table test—ordered to evaluate syncope
For more information on imaging tests, visit RadiologyInfo.org.