For patients with coronary risks, a noninvasive scan provides reliable answers

It’s a sobering statistic: Heart disease is the leading cause of death for men, women, and people of most racial and ethnic groups in the United States. The most common type of heart disease is called coronary artery disease, or CAD. 

Unfortunately, some people do not realize that they have CAD until experiencing their first heart attack. Our healthcare specialists with Mecklenburg Radiology Associates want to help patients discover their risk factors sooner and prevent heart attacks. Our providers use state-of-the-art imaging technology to help diagnose heart disease without invasive procedures.

We spoke with Dr. Frank W. Petraglia III, an MRA diagnostic radiologist with specialties in cardiovascular and body imaging, to tell us about a noninvasive procedure called computerized tomography coronary angiogram, or CT coronary angiogram. This sophisticated imaging test is low risk to the patient and can be used instead of cardiac catheterization, an invasive procedure requiring sedation in which a needle is inserted, usually through the groin, and threaded through to the coronary arteries. 

What is the purpose of a CT coronary angiogram?

• To not only detect coronary artery disease but to evaluate the degree of narrowing in the affected arteries. 
• If narrowing is identified, the test can determine the severity and whether it is causing low blood flow to the heart. 
• This technology can evaluate the composition of the material, or plaque, that is built up in the arteries. If plaque inside the arteries ruptures, it can cause a heart attack. Knowing the composition of the plaque helps clinicians predict heart attack risk.

“The exciting thing about CT coronary angiograms,” Dr. Petraglia said, “is that this technology has gone through multiple improvements in recent years, while other noninvasive studies such as nuclear medicine stress tests have not changed very much in a long time.” 

When is a CT coronary angiogram indicated as a first-line test?

• Recent guidelines recommend CT coronary angiogram for patients with no known coronary artery disease who present with chest pain or other symptoms that are thought to represent a possible heart attack (e.g., shortness of breath on exertion or jaw pain). 
• It can also be used to evaluate patients with known coronary artery disease who present with those symptoms or after an inconclusive stress test.

What should patients know about how the test works?

• Before the CT coronary angiogram, patients take medicine to lower the heart rate so that images do not come out blurry. Patients are also given a nitroglycerine tablet that dissolves under the tongue, which dilates the coronary arteries and makes them easier to evaluate. 
• The first portion of the exam is a CT scan of the heart used to quantify the amount of calcium, or plaque buildup, in the coronary arteries. This coronary artery calcium score can be used to guide medical treatment and help clinicians predict a patient’s future risk for heart attack. 
• Next is the actual scan. Contrast dye is injected into the patient through an IV and another CT scan of the heart is performed. 
• Dr. Petraglia notes that this test does expose the patient to radiation, but a special technique reduces the dose to the lowest possible level.   

What techniques do MRA radiologists use with CT coronary angiograms that provide an added benefit to patients?

• A technique called prospective ECG-gated imaging. This technique syncs the CT scanner to the patient’s heartbeat. However, it scans only during a specific portion of the heartbeat rather than during the entire heartbeat, which decreases the total radiation exposure to the patient. 
• Fractional flow reserve computed tomography or FFRCT. This is an additional analysis that happens after the exam is over.
  • Images are sent off for further evaluation.
  • Software models the blood flow through the coronary arteries.
  • Clinicians evaluate whether areas of narrowing are severe enough to cause low blood flow to the heart. Low blood flow to the heart can cause chest pain and/or a heart attack. 
  • If the area of narrowing is causing low blood flow, it will often be treated by placing a stent – a tube-shaped device used to open up the narrowing. If the area of narrowing is not causing low blood flow to the heart, the patient will often be treated with medication. 
  • This analysis helps the healthcare team determine the optimal treatment course for the patient without using invasive methods.

How do CT coronary angiograms compare to other types of cardiac testing? 

• Unlike a cardiac catheterization test, this exam cannot treat the narrowing of the arteries during the same procedure. But, as CT coronary angiograms are noninvasive, they are lower risk and take much less time. 
• Compared to another commonly used noninvasive exam, the cardiac stress test, CT coronary angiograms are more accurate. The test’s ability to detect someone who is positive for hemodynamically significant CAD (i.e., CAD that causes low blood flow to the heart) is 99%, compared with 82% for nuclear medicine stress tests.

To find out more about this remarkable procedure and the radiologists who perform it, contact us at 704.384.9654 or request a consultation.