Why isn’t the CT angiogram used commonly in emergency rooms to evaluate chest pain?
Studies have shown the value of the CT angiogram in distinguishing ER patients with cardiac chest pain from those with non-heart related chest pain.
One such study appeared in the July 26, 2012 New England Journal of Medicine.
The paper states that the use of coronary CTA in an emergency room setting for acute chest pain was very effective at identifying which patients did or did not have a blockage in their coronary arteries.
This allowed clinicians to then focus on the use of resources for patients with clogged arteries.
Despite this compelling finding, however, chances are pretty high that if you walk into an ER complaining of chest pain, you will not undergo the CT angiogram.
These studies show effectiveness, but they don’t focus on something else: the impact of radiation from the CTA.
“The use of CT angiograms (CTAs) of the chest in the ER setting is reserved for the evaluation of specific conditions to prevent patients from receiving unnecessary radiation,” says Brett Mollard, MD, a board certified diagnostic radiologist who specializes in abdominal and chest imaging.
“While ionizing radiation from a single CT scan of the chest has a very low overall risk to a patient, the risk is not zero and can have a cumulative effect in patients who receive multiple CTs over time,” continues Dr. Mollard.
“ER providers therefore limit ordering CTAs unless they have specific concern for disease processes such as pulmonary embolism or aortic injury (dissection or rupture).
“Coronary CTA is also becoming increasingly used in patients with low to intermediate risk of having an acute coronary syndrome (ACS).”
Three Flavors of CT Angiogram
Dr. Mollard explains, “CTAs of the chest come in three flavors: CTA of the pulmonary arteries to evaluate for pulmonary embolism; CTA of the thoracic aorta to look for an acute aortic injury such as a dissection, intramural hematoma or tear; and coronary CTA to assess for the presence of coronary artery disease.
“These differ by timing of imaging following contrast administration and whether or not ECG-gating is performed.
“A CTA of the thoracic aorta frequently also sufficiently evaluates the pulmonary arteries, and special protocols exist that are designed to diagnostically evaluate both the thoracic aorta and pulmonary arteries at the same time with a single scan.”
Thus, for people entering an emergency room complaining of chest pain, they will typically get a chest X-ray, ECG and a blood draw for a heart enzyme – like my mother did on several occasions when her symptoms included the possible differential diagnosis of heart attack.
However, the first time she went in for trouble breathing (which can mean a heart attack or looming heart attack) — had she been given the CT angiogram on that visit, she would have been admitted instead of sent home with a suspected diagnosis of acid reflux, because logically, the CTA would’ve come up with a very troubling finding that the chest X-ray, ECG and enzyme test missed: dangerously blocked arteries.
Several days later she was back and had been admitted due to the enzyme test having a “grey area” result.
A catheter angiogram revealed very severe coronary artery blockage — something that a CT angiogram would have picked up.
Nevertheless, from an overall picture, there’d be a lot of unnecessary radiation exposure if the CTA was a standard test for everyone, including those with cardiac risk factors, who reported chest pain in the emergency room.
Brett Mollard, MD
