Coronary Scan FAQ’s

Cholesterol screens, stress tests and other traditional risk stratification methods, such as the Framingham criteria, are still the backbone of understanding the risks for a patient to develop coronary artery disease (CAD). For 20 years, stress testing has been the standard of care for diagnosis of CAD. Although stress testing identifies most patients with a severe blockage in their coronary arteries, 15-20% will have a falsely negative or inconclusive test result. More than 2/3 of patients with significant plaque, but no blockage, will have a normal exam. And, stress tests have higher radiation exposure for patients compared to both the CCTA and calcium scoring tests.

Studies have shown that 20-30% of cardiac catherizations are negative, due largely to false positive stress test results. In 2006, Budoff and colleagues published a joint society statement in Circulation based on evidence on the use of CCTA. All studies have convincingly demonstrated a very high negative predictive value; a “normal” CCTA allows a clinician to rule out the presence of CAD with a high degree of reliability. In a clinical context, the high negative predictive value may be useful for obviating the need for invasive heart catherizations.

1. What is a Coronary CTA?

CCTA is a non invasive heart imaging test done with a 64 slice CT scanner with high resolution, 3-dimensional pictures of the heart and coronary arteries. Coronary CTA detects both early soft plaque and calcifications. 85% of myocardial infarctions (MI’s) are the result of eccentric soft plaque ruptures.

2. What is a calcium scoring test?

The calcium score screening heart scan is a non invasive test done with a 64 slice CT scanner and used to detect calcium deposits in atherosclerotic plaque in coronary arteries. This is the most effective way to detect coronary calcification before symptoms develop. The amount of coronary calcium has been recognized as a powerful independent predictor of future cardiac events and may be used to guide lifestyle modifications to reduce risk.

Both are done on a 64 slice CT scanner. Both are done as outpatient tests and both require a script from a physician.

The Calcium Scoring test takes less than 10 minutes. The patient lies on the scanner table and the CT takes 3-D images of the chest. No drugs or IV’s are required for this test. The Calcium Scoring test provides calcium (hard plaque) scores.

The Coronary CTA takes approximately 45 minutes and requires an IV of contrast and a beta blocker to slow the heart rate. Coronary CTA provides both the calcified plaque burden as well as the soft plaque burden which occurs earlier than calcifications.

4. Does insurance pay for these tests and what is the cost?

Because some insurance companies do not pay for these tests, the out of pocket expense may limit the patients who will choose to have them. The calcium scoring test is considered a screening test by insurance companies, but may be covered. Cost: $195.00

Coronary CTA is covered by Medicare, Highmark and Oxford. Patients should check with their insurance carriers to determine coverage. Cost: $1,150.00

5. What patient should be considered for Coronary CTA?

According to the 2006 Appropriateness Criteria for CCT/CMR the following are appropriate indications:

Detection of Coronary Artery Disease with symptoms-evaluation of chest pain syndrome
• Intermediate pre-test probability of CAD
• ECG uninterpretable OR unable to exercise

Detection of Coronary Artery Disease with symptoms and previous test results:
• Uninterpretable or equivocal stress test (exercise, perfusion, stress echo)

6. What patient should be considered for Calcium scoring?

Calcium scoring has been shown to be most useful for the asymptomatic patients who are at intermediate risk by Framingham criteria. This test can be helpful in this patient population if the serum LDL is borderline or if the statin therapy does not decrease LDL sufficiently. The calcium scoring test can be done at the same time as the Coronary CTA or done independently.

7. What is the radiation exposure from these tests?

The use of the new 64 slice CT scanner reduces the dose used as well as the time spent on the scanning table. In 5 heartbeats this CT scanner captures hundreds of 3-D images. The use of breast shields is another dose cutting tool which reduces the dose to the breasts by up to 35%. LVDI adheres to the ALARA principles which expose the patient to the lowest amount of exposure while providing the best diagnostic images.

The table below compares doses of commonly ordered tests measured in Milliseverts (mSv):

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