Cardiac CT, Ultrasound, MRI and More: Which Tests Are Used When for CAD?

Major advances in cardiac imaging technology have dramatically improved physicians' ability to detect heart disease and improve patient care, especially with coronary artery disease (CAD), the most common type of heart disease in the United States, which is responsible for over 370,000 deaths a year.1,2 

CAD occurs when fatty deposits called plaque build up in the blood vessels or arteries that supply blood in or to the heart.2 Over time, the plaque build-up narrows the arteries and blocks blood flow to the heart; that blockage can result in chest pain, which could increase the risk of heart attack and other serious heart-related complications.The symptoms of CAD typically include chest pain and trouble breathing, especially when you are active; although for some individuals, the first symptom of CAD may be a fatal heart attack.4 The risk factors for developing CAD include age over 60, smoking, high blood pressure, being overweight or obese, diabetes, high cholesterol, and a family history of heart disease.4 While chest pain is usually the first signpost that you may have heart disease, it’s estimated that almost half a million people die each year in the U.S. of an unexpected heart attack, emphasizing the importance of early and accurate diagnosis of CAD in order to reduce life-threatening events.5

Diagnosis and Assessment of Coronary Artery Disease

Because chest pain is such a common complaint, the guidelines of the American College of Cardiology and the American Heart Association (ACC/AHA) recommend that as a first step in evaluating chest pain and making a diagnosis of CAD, a baseline examination be performed.6 This examination includes a medical history, physical examination, and an electrocardiogram (ECG); a five to 10-minute test that measures the electrical activity of your heart by placing electrodes on the skin.6 This basic test can be performed in your primary care physician’s office or in an outpatient hospital setting.  Because the exam and ECG, may not always provide enough information to rule out more serious forms of CAD, the guidelines suggest that patients with possibly more serious disease, as well as some low-risk patients, undergo an exercise ECG, such as a treadmill stress test.7 Exercise stress tests have the advantage of revealing problems in how well the heart is functioning that are not noticeable when you are at rest.4,7 

Cardiac Ultrasound

While the exercise stress test is a useful diagnostic tool and relatively easy to perform, it’s not always as sensitive as other tests in detecting the degree of your CAD and heart attack risk.8 An echocardiogram, or ultrasound of the heart, uses high-frequency sound waves to provide more detailed moving pictures of the heart, including how well the blood is flowing through your arteries.9 Echocardiograms can also be performed while you exercise (stress echocardiogram) and offer the advantage of being a noninvasive test with no radiation exposure.10 Advances in ultrasound technology have included the development of portable ultrasound machines that can be used in hospital emergency departments, or at a patient’s bedside.

Cardiac MRI

Increasingly, cardiac magnetic resonance (CMR) is considered the new “gold standard” in assessing warning signs of blockages by looking at both the structure and functioning of the heart.12  The extremely detailed images produced by the CMR are regarded as superior in quality to echocardiograms and can also be used as a “second opinion” in situations where the diagnosis of CAD is unclear.13 However, currently, CMR imaging is not available in many hospitals and specific skills are needed to perform and interpret the test results.12


Increasingly, coronary computed tomographic angiography (CCTA), or a CT scan of the heart, is being more widely used in patients who have a low to intermediate risk of having CAD. CCTA has the advantage of being a noninvasive test that produces highly detailed images of the structure of the heart, providing excellent accuracy in assessing patients who are not at high risk for serious CAD.13,14,15


If a patient’s testing or symptoms indicate intermediate or more serious risk factors for a heart attack, a test called an invasive coronary angiography (ICA) may be recommended.15,16,17 The ICA has traditionally been considered the “gold standard” for assessing the extent of the narrowing of the coronary arteries and blockages.17 As its name suggests, an ICA is an invasive procedure in which the patient lies down on an examination table while the technician inserts a small catheter through the skin into an artery in the groin or arm. A contrast solution is injected into each coronary artery and a special type of x-ray called a fluoroscopy is used to visualize the location and severity of the blockages.16 The results can help determine the degree of blockage within the arteries and the types of treatments the patient may need, which can range from medication therapy to coronary bypass surgery.  

Other Options in Noninvasive Cardiac Testing

Patients who have established CAD, or have had heart attacks, may also undergo nuclear imaging testing that uses radioactive tracers to evaluate blood flow to the heart.13 Cardiac positron emission tomography (PET) is another imaging test that can be combined with other tests to detect CAD, although it’s used less frequently than nuclear imaging and stress echocardiography.12


As these advanced imaging technologies become more widespread, they offer physicians many more choices for diagnosing and assessing CAD—and vastly improved outcomes for patients who may be at risk for heart attack and other serious complications of CAD.


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