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.
When someone presents to the emergency room with 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.
Heart disease that is causing few symptoms may be detected during a visit to a doctor for nonspecific symptoms such as fatigue. The doctor may order a variety of blood and other tests to investigate possible causes for the person's symptoms.
Testing people for existing heart disease is not the same as cardiac risk testing. Cardiac risk testing is performed to screen asymptomatic people to help determine their risk of developing coronary heart disease.
Laboratory Blood Tests
Cardiac biomarkers, proteins that are released when muscle cells are damaged, are frequently ordered when someone has symptoms of acute coronary syndrome, such as chest pain, pain in the jaw, neck, abdomen, back, or that radiates to the shoulder or arms, nausea, dyspnea, 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.
- Myoglobin – a protein released into the blood when heart or skeletal muscle is injured; this test is rarely used now.
- 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
- 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.
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.
More general blood tests that may be ordered include:
- Blood Gases – performed to evaluate oxygen, carbon dioxide, and pH levels
- Complete 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
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, CAD, 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
- 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.