A heavyset, 51-year-old truck driver with a history of hypertension presented at Norton Heart & Vascular Institute with four months of intermittent, sharp, substernal chest pain that was exacerbated by activity and becoming increasingly frequent.

Should he be evaluated with anatomic or functional testing?

Updated clinical practice guidelines offer guidance on whether to choose coronary CT or exercise treadmill stress electrocardiography for the outpatient evaluation of chest pain.

In their first-ever chest pain guidelines, the American Heart Association and American College of Cardiology determined that both coronary CT and a treadmill stress test are effective diagnostic tools. Deciding whether to choose one or the other comes down to the severity of disease and a clinical risk assessment, according to the AHA and ACC.

For a patient such as the truck driver, with no known heart disease, he would first undergo a clinical risk assessment using the Diamond Forrester model or some other measure.

Under the AHA/ACC guidelines, low-risk patients receive no further testing.

The truck driver was assessed as intermediate risk. In shared decision making with the patient, either coronary CT or treadmill EKG can be used for intermediate-risk patients.

“I think the advantages for coronary CT is it allows you to get an anatomic assessment, which does allow you to pick up presymptomatic disease or early atherosclerotic disease. It may not be the cause of the patient’s chest pain, but it does offer further risk stratification and allows us to optimize medical therapies,” said Arpit Agrawal, M.D., cardiac imaging and cardiologist with Norton Heart & Vascular Institute.

Dr. Agrawal presented on cardiac diagnostic imaging during the monthly Clinical Case Review continuing medical education opportunity.

Case study: CT-FFR analysis shows patient’s level of cardiac obstruction and location, guiding treatment

Anatomic testing also can accurately identify patients with multivessel coronary artery disease, which may be missed by functional testing; and it can assess for left main coronary artery disease and anomalous coronary arteries.

In addition, coronary CT allows for the characterization of plaque, including the identification of low attenuation or soft plaque, which is associated with a higher risk of myocardial infarction. This can guide more aggressive medical therapy.

A normal coronary CT also has a stronger negative predictive value compared with a negative stress test. Under the AHA/ACA guidelines, patients with a normal coronary CT have a low risk of atherosclerotic events and require no further testing for two years, while stress testing offers a one-year warranty period.

Norton Heart & Vascular Institute also offers fractional flow reserve-CT, a noninvasive method for evaluating patients with intermediate-risk stenosis to assess the functionality of their stenosis by looking at functional flow reserve, something previous done with invasive coronary angiograms. FFR-CT maps the whole coronary tree and all the blockages, estimating what the FFR would be.

While coronary CT is increasingly used as a diagnostic tool, stress testing still has an important role, particularly in patients who have a higher pretest probability of disease, which includes older patients and patients who have unstable heart rates, renal dysfunction or sensitivity to IV contrast.

For patients who have known coronary disease or previous intervention or CABG, stress testing generally is the first test, according to Dr. Agrawal.

Anatomic testing requires a controlled heart rate, which may be challenging for some patients. Taking pictures of the heart using coronary CT relies on periods of time when the heart is standing still, typically mid-diastole. Scans of patients with a fast heart rate result in more artifacts and uninterpretable studies.

Ideally, patients should have a heart rate below 60 for coronary CT, which can be achieved using oral metroprolol or ivabradine. Stress testing does not require heart rate control.

Another advantage of stress testing is that it can assess functional capacity and reproduce symptoms. If a patient has chest pain every time they run, stress testing allows clinicians to reproduce the symptoms and see exactly what is happening to the patient’s EKG while running, which can be helpful.

A final potential advantage of stress testing is that it is more readily available than coronary CT, especially at smaller clinics outside of Louisville, Kentucky.