Many factors must be considered when choosing imaging test for chest pain
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For patients with chest pain, there is no single imaging test that will provide the perfect diagnosis for all, according to a speaker at the American Society for Preventive Cardiology Congress on CVD Prevention.
Ron Blankstein, MD, FACC, FASNC, MSCCT, FASPC, associate director of the cardiovascular imaging program, the director of cardiac computed tomography, co-director of the cardiovascular imaging training program and director of cardiac computed tomography at Brigham and Women’s Hospital and professor of medicine at Harvard Medical School, said during a presentation that it is important to learn which imaging modalities are most appropriate for specific kinds of patients.
“Imaging tests alone do not change patient outcomes, but it’s how we act on them that might change them,” said Blankstein, who is also the immediate past president of the Society of Cardiovascular Computed Tomography. “There is no one test that is always the best test.”
In that case, the burden is on clinicians to select the best test, requiring them to rely on local availability and expertise, which may be driven by economic factors, and to consider what makes the most sense for each patient and is consistent with guidelines, Blankstein said.
A multisociety guideline on management of chest pain will be released soon and should help in that area, he said.
Most tests fall into one of two categories, stress tests or anatomical tests, Blankstein said.
Treadmill tests are useful to assess exercise capacity and changes in hemodynamics or ECG parameters as a result of exercise.
They “are not very accurate for diagnosing ischemia, but the amount of time a patient can exercise is still prognostically important and often can be helpful to tell us if a patient is doing well,” Blankstein said.
Stress echocardiography is designed to detect wall-motion abnormalities after exercise, whereas “nuclear stress testing with single-photon emission CT myocardial perfusion imaging provides a qualitative assessment of ischemia by looking for reversible perfusion defects,” Blankstein said. “One downside of this test is it underestimates the downside of disease because it looks at relative differences in blood flow.”
PET myocardial perfusion imaging is more accurate than SPECT because it offers attenuation correction and can measure absolute blood flow, thus better assessing multivessel disease, he said.
Stress MRI can be used to evaluate for ischemia, “and often we send patients for this test when there are other compelling reasons to do a cardiac MRI; for example, if we are interested in myocardial disease.”
In addition, he said, rest MRI “is the most robust technique to ... look at pericardial inflammation in a case of suspected pericarditis.”
The advantage of coronary CT angiography is that it can “detect a wide spectrum of disease,” Blankstein said, noting it has the highest sensitivity of any modality to detect stenosis, with comparable specificity to alternatives. For example, he said, coronary CTA can detect minimal or mild stenosis, which would show up as normal on a stress test.
Coronary CTA’s ability to detect plaque “is important, and three reasons for that ... are that, No. 1, most stress tests done in the U.S. today are normal ... No. 2, a substudy of PROMISE showed that most patients who have stable chest pain who go on to have events had normal stress tests prior to their event, and No. 3, we have seen several studies showing us the overall amount of plaque that patients have is the strongest predictor of future events, and it predicts risk even more so than whether patients have anatomical stenosis,” Blankstein said.
Even more important, he said, there are now data, initially from SCOT-HEART but now other studies as well, showing that patients randomly assigned coronary CTA have improved outcomes compared with those assigned the standard of care.
The curves separate over time, “suggesting it’s actually preventive therapies as opposed to a treatment at baseline that’s responsible for the differences,” he said.
Coronary CTA is likely the best option for patients who have no known CAD and for whom good image quality is probably, Blankstein said, noting it is not useful for patients with known CAD, patients with morbid obesity (due to issues with image quality), patients with extensive coronary artery calcium (due to issues with image quality) and patients with small stents.
“We have to understand if our patient has a history of coronary disease or not,” he said. “We always have to consider the local availability and expertise. We always have to think about the results of prior tests, and if they were helpful. And we have to think of the clinical scenario at hand, which is where judgment and experience is important.”
References:
- Budoff MJ, et al. Circulation. 2017;doi:10.1161/CIRCULATIONAHA.117.030578.
- Mortensen MB, et al. J Am Coll Cardiol. 2020;doi:10.1016/j.jacc.2020.10.021.
- SCOT-HEART Investigators, et al. N Engl J Med. 2018;doi:10.1056./NEJMoa1805971.
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Blankstein R. Ischemic Heart Disease. Presented at: American Society for Preventive Cardiology Congress on CVD Prevention; July 23-25, 2021 (virtual meeting).
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