How Coronary Artery Disease Is Diagnosed

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Coronary artery disease (CAD) risk can often be assessed with blood tests. Mild, early stage CAD is diagnosed with specialized diagnostic tests such as echocardiogram and angiogram. The consequences of CAD, including heart muscle dysfunction and alterations in heart rhythm, can be more easily detected than early CAD using a variety of diagnostic assessments and tools, including physical examination and tests of heart function.

When CAD is identified before it causes serious health consequences, the treatment can be more effective and can prevent complications such as heart attacks and arrhythmias. 

coronary artery disease diagnosis
Illustration by Verywell  

Self-Checks

Often CAD does not produce symptoms, so it does not lend itself to easily self-checking for signs and symptoms. However, if you do experience them, it's important to bring them to your doctor's attention. You cannot diagnose yourself with CAD, but, likewise, you cannot dismiss a potential diagnosis on your own either.

Pay attention to the following. Though they may indicate another concern, they could also point to CAD:

  • Fatigue
  • Shortness of breath with exertion
  • A decline in your level of physical activity endurance
  • Chest pain/chest discomfort with exertion
  • Arm or jaw pain/discomfort
  • Indigestion

If you experience any of these, or other symptoms you can't explain (shortness of breath at rest, palpitations, dizziness), it is still well worth your time to talk to your doctor and have a medical evaluation.

Labs and Tests

Several tests can assess whether you have a high likelihood of developing or already having CAD. In general, these tests do not directly identify CAD, but they can identify the causes. 

Blood Pressure

Hypertension is among the leading causes of atherosclerosis and CAD. Hypertension is relatively easy to check for using a blood pressure cuff. Since some people experience "white coat hypertension," which is an elevated blood pressure related to anxiety in a medical setting, repeating measurements is generally recommended.

Usually, if your blood pressure is normal at the doctor's office, there is no reason to worry about hypertension. But if it is high, that could be a false reading that needs to be verified. 

Electrocardiogram (EKG)

A non-invasive electrical test, an EKG can assess for evidence of heart muscle weakness and heart rhythm irregularities. There are many causes of EKG abnormalities, and damage to the heart due to CAD is among the causes. 

Blood Cholesterol and Triglyceride Levels

High blood cholesterol and triglyceride levels can indicate that you either have CAD or are at risk of developing CAD. 

Blood Glucose Levels

High fasting blood sugar levels can mean that you have diabetes. Depending on your results, you may need another test, a hemoglobin a1c test, which assesses your blood sugar levels over a period of months. This can determine whether you have diabetes, which is among the causes of atherosclerosis and CAD.

Imaging

Imaging tests can be especially helpful in diagnosing CAD. These tests can examine the structure and function of the heart. Traditionally, the diagnosis of CAD has relied on tests that look for evidence of significant blockages in the coronary arteries. In general, cardiologists consider a significant blockage to be one that obstructs 70 percent or more of an artery's channel.

Nuclear Stress Test

With a stress test, your heart function is tested under a time of increased demand in a controlled setting. You may be asked to exercise or you might be given medication. While most are familiar with an EKG being used to monitor heart function, an imaging test, such as an ultrasound, may also be used to see how your heart responds when demand increases.

Often, people with CAD have alterations in heart function when the heart undergoes increases in demand. Exercise testing is often helpful in diagnosing partially blocked coronary arteries. Controlled stress testing can often bring out symptoms of angina and characteristic changes on the electrocardiogram (ECG) or echocardiogram—findings that strongly suggest that blockages are present.

Echocardiogram (ECG)

An echocardiogram (echo) is a non-invasive imaging test that uses ultrasound to observe your heart in action. Your doctor and technician can observe the pumping of your heart from different angles and asses for narrow blood vessels, irregularity of your heart muscle function, valve problems, and irregular rhythm. 

Thallium and cardiolite are radioactive substances that are injected into a vein during exercise. These substances are carried to the heart muscle by the coronary arteries, thus allowing the heart to be imaged with a special camera.

If one or more of the coronary arteries are partially blocked, the areas of heart muscle supplied by those arteries show up on the image as dark spots. 

Multislice CT Scan and Cardiac MRI

Noninvasive imaging tests can assess the anatomical structure of the heart. Neither of these approaches is considered as informative for an initial diagnosis of CAD as an echocardiogram or cardiac catheterization, but they may be used to give your doctors more information about your CAD, specifically for treatment planning to.

Calcium scans are emerging as a useful way of detecting the presence of even small amounts of CAD. Calcium scans are a form of CT scanning that can quantify a number of calcium deposits in the coronary arteries. Since calcium deposits generally occur in plaques, measuring the amount of calcium in the arteries yields an indication of whether CAD and therefore plaques, is present as well as how extensive the CAD may be. 

Angiogram

An invasive diagnostic procedure, an angiogram involves placement of a catheter (tube) into your blood vessels while your chest is being examined with an X-ray or ultrasound. This test evaluates how well the blood vessels fill with blood and whether there is any obstruction. This is a direct way to view the structure of the coronary arteries. 

Differential Diagnoses

Other medical conditions can manifest with chest discomfort or shortness of breath. Some of these conditions, like CAD, also require medical management.

Your medical history, including the frequency, progression, and duration of your symptoms generally helps guide your doctors in terms of diagnostic testing. In general, a heart attack is considered the most serious of these diagnoses, and if you have symptoms suggestive of one, your doctors will rule that out with emergency EKG before moving on to testing that is more tailored to your symptoms. 

It is also possible that you could have CAD in addition to one of these other conditions. 

  • Gastroesophageal reflux disease (GERD): Often described as heartburn or indigestion, GERD can cause pain and discomfort that is typically associated with eating, particularly after eating spicy foods. The burning pain of GERD tends to worsen with lying down and is not closely associated with stress and physical exertion the way symptoms of CAD are. 
  • Asthma: Characterized by sudden and severe episodes of shortness of breath, asthma typically begins at a young age. It can be difficult to know whether your shortness of breath is related to asthma or CAD, and you should seek emergency medical attention until you have a diagnosis and a treatment plan. 
  • Chronic obstructive pulmonary disease: Disease of the lungs causes shortness of breath, which typically worsens with exertion. A physical examination in your doctor's office, as well as diagnostic tests, can distinguish between the conditions. 
  • Aortic stenosis: The aorta is the largest blood vessel in the body, sending oxygenated blood from the heart to the rest of the body. Narrowing of the aorta is a serious condition that can cause low energy, chest pain, and even loss of consciousness. Diagnostic tests can differentiate between aortic stenosis and CAD. 
  • Anemia: A condition in which the red blood cells do not function as they should, anemia is characterized by low energy. If you have anemia, it can be diagnosed with a blood test. 
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