URA Highlights

Coronary CT Angiography Now Available at Utah Valley Regional Medical Center

Coronary Artery Disease (CAD) is a serious health problem in the United States. It is estimated that over 13 million people in the United States have coronary artery disease. More than 500,000 people will die of heart attacks this year, and of those about 1/3 to 1/2 will have no prior warning.

About six million people will be seen in emergency rooms this year because of chest pain. Many of these patients will have non-coronary causes of their chest pain, but sorting out those with CAD and those without CAD can be a diagnostic challenge. Early diagnosis of CAD is important for early intervention to prevent heart attacks and death.

Diagnostic Tests for CAD
After ruling out myocardial infarction, different imaging and diagnostic tests have been used to evaluate for blockage of the coronary arteries. Stress EKG, stress echocardiography, and stress nuclear medicine tests are often used to help diagnose a significant coronary obstruction. Unfortunately, these tests are insensitive for the detection of early coronary artery disease, and will not detect disease typically until coronary arteries have narrowed to at least 70%. Diagnostic coronary angiography is much more sensitive in detecting coronary disease, but it is invasive, has some risk, and is expensive.

As CT technology has advanced, the ability to accurately and non-invasively detect early coronary artery disease has improved. With the advent of 64 detector technology, CT coronary angiography has become clinically relevant as an important tool in diagnosing CAD.

What is Coronary CT Angiography?
Coronary CTA (CCTA) is a non-invasive, very fast, EKG-gated contrasted CT examination of the heart which allows visualization of both the lumen and wall of the coronary arteries. The high spatial and temporal resolution of 64 slice CT provides a multi-dimensional view of coronary arteries to detect CAD. CCTA allows detection of coronary atherosclerotic plaque which may or may not be causing obstruction. “Soft” cholesterol-laden atheromatous plaque can also be detected. This disease may not yet have caused blockage, but is at risk for plaque rupture and thrombosis which causes myocardial infarction and death.

CCTA has high sensitivity ranging from 82-95%, significantly better than any currently available non-invasive coronary imaging test. CCTA’s negative predictive value is 97-99%. Therefore, CCTA can confidently exclude CAD. In other words, if it’s negative, it’s negative.

In addition to CAD, CCTA has the ability to detect other important findings that could be related to the patient’s clinical presentation. These findings might include pulmonary embolus, pneumonia, hiatal hernia, pulmonary nodules or masses, mediastinal or hilar adenopathy, bronchiectastis, aortic aneurysm or dissection.

Who is a Candidate for CCTA?
According to appropriateness criteria set forth by the ACC and ACR, CCTA is best suited for the following types of patients:

• Intermediate risk with atypical chest pain
• Acute chest pain, intermediate risk, negative EKG and enzymes
• Acute chest pain, high risk, negative EKG and enzymes
• S/P CABG with recurrent chest pain
• Suspected coronary variants (young persons with exercise-induced chest pain)
• Uninterpretable or equivocal stress test
• New onset heart failure (ischemic vs. dilated)
• Cardiac mass or pericardial disease

Coronary Calcium Scoring
Although there is some controversy regarding the utility of coronary artery calcium scoring, there is clear evidence that calcium scoring can aid in risk stratification of low and intermediate risk patients. A person with no calcium in their coronary arteries has a very small chance of atherosclerotic disease, lower risk than would be predicted by the Framingham criteria. Also, a patient with a calcium score greater than 100 has a risk of myocardial infarction 10x that of the normal population.

Summary
Coronary CTA is revolutionizing the diagnosis of CAD. It provides patients with a non-invasive, lower cost imaging examination that accurately detects atherosclerotic plaque. Early diagnosis of CAD can help physicians intervene early to prevent myocardial infarction and death.

Utah Radiology Associates, in cooperation with local cardiologists, have instituted the Coronary CT Angiography program at Utah Valley Regional Medical Center (UVRMC). The hospital has installed the high-end Volume CT 64 slice scanner with cardiac processing software. Appointments are now being accepted for Coronary CTA at the UVRMC Radiology Department.