November 2013

Emergency Response
By Beth W. Orenstein
Radiology Today
Vol. 14 No. 11 P. 24

The debate continues over whether to use coronary CT angiography in low- to moderate-risk patients presenting with chest pain.

A patient comes to the emergency department (ED) complaining of acute chest pain. His EKG and blood enzymes are normal, so the results don’t suggest a heart attack. Do you keep the patient for observation? Send the patient home without further testing? Or do you order a coronary CT angiography (CCTA) to be absolutely sure?

There are two schools of thought on the best course of action. One is that low- to moderate-risk patients should be sent for CCTA to rule out coronary artery disease and reduce the likelihood of their returning to the ED in a few weeks or months—this time with a heart attack.

“I am a board member of the FiRST [Fellow and Resident Leaders] Committee of the Society of Cardiovascular Computed Tomography, and one of our main objectives this past year has been to get the word out about CCTA,” says Christopher Maroules, MD, who specializes in diagnostic radiology at the University of Texas Southwestern Medical Center in Dallas.

Several recent randomized trials have demonstrated that CCTA is an effective strategy for evaluating low- to intermediate-risk patients who present to the ED with chest pain, Maroules says. Based on growing evidence, he and several of his colleagues believe CCTA is not only a valuable triage strategy but also a cost-effective approach.

Others, including Rita Redberg, MD, MSc, a cardiologist and professor of medicine at the University of California, San Francisco, argue CCTA in low- to intermediate-risk patients is unnecessary and doesn’t lead to improved outcomes or cost savings. “People who have an unimpressive story, minimal or no EKG changes, and no blood enzyme elevations can go home safely without a CCTA,” she says. The question, she notes, really isn’t whether these patients need a CCTA but whether they need any test.

Reimbursement Issues
Geoffrey D. Rubin, MD, FACR, a professor of radiology and bioengineering at Duke University in Durham, North Carolina, says evidence that CCTA can make an important contribution to clinical decision making and patient management is rapidly expanding. If it weren’t for reimbursement issues, he says, it would be more widely adopted based on the growing evidence of its efficacy.

The Centers for Medicare & Medicaid Services (CMS) does not have a national coverage determination for CCTA. “Consequently, reimbursement is heterogeneous,” Rubin says. “It’s often a matter of who the patient’s insurance carrier is or where in the country the patient lives.” Reimbursement is complicated, and “it becomes a barrier just because it’s not as straightforward as other kinds of diagnostic imaging.”

Why doesn’t the CMS have a national coverage determination for CCTA? Only the CMS can answer that question, Rubin says. However, he suspects it has to do with a concern that CCTA could uncover incidental findings that would lead to more costly studies and treatments downstream. “I’m sure what they would say is they want to see more data that establishes that there is no increase in downstream costs associated with the use of CCTA,” he says.

Advocates for CCTA in the ED say there are not additional downstream costs and that, if anything, CCTA reduces them. Ricardo Cury, MD, FAHA, FSCCT, president and CEO of Radiology Associates of South Florida, says CCTA to rule out coronary artery disease reduces costs in two ways. One is that patients can be safely discharged sooner, and the other is the likelihood of their returning to the ED with a myocardial infarction is greatly reduced.

The cost for a CCTA varies depending on the location but generally is between $500 and $1,000; if the test yields negative results for a heart attack, the patient can be discharged within hours without additional costs. If the physician is unsure and the patient must be admitted to the hospital for observation or to undergo stress testing, the cost typically is greater than $3,000 a patient, Cury says. More importantly, he says, several studies show that 2% to 4% of low- to intermediate-risk patients who, despite having negative enzymes and negative EKGs, return to the ED with a myocardial infarction within 30 days. “And that’s exactly what you want to avoid,” Cury says.

When Cury’s institution implemented a protocol that sent low- to intermediate-risk patients for CCTA, it reduced their length of stay in the ED by 50%. “We went from 28 hours to 14 hours, which is not only good for the patients and their families but also saved the hospital and the health care system money and resources,” he says. “By adding CCTA, you are decreasing length of stay, decreasing costs, and making the system more efficient. You also are improving the patient experience. No patient wants to be in the hospital for two days when you can be in for 12 to 14 hours.”

Advocates say the radiation from the CT scan does not threaten patient safety. It’s true that every time a patient is scanned, the patient is exposed to ionizing radiation, Maroules says. However, the traditional method for determining whether a patient has acute coronary syndrome (nuclear stress testing) also uses ionizing radiation, he notes. “If you put CCTA head-to-head with nuclear stress testing, the radiation exposure from CCTA generally is lower, particularly with modern CT scanners and dose reduction strategies,” he says.

Radiation exposure may have been a concern four to five years ago, Cury adds, “but I don’t think it’s a concern now that the average radiation dose for CCTA is less than 5 mSv compared to 10 to 12 mSv for myocardial perfusion imaging with SPECT.”
Part of the reduced radiation dose comes from improvements in technology. “People are finding ways to acquire CCTA with very high image quality in patients with less than 1 mSv of radiation exposure, which is just astounding,” Maroules says.

Furthermore, a negative CCTA could mean less radiation over time for the patient, according to Maroules. If the patient undergoes CCTA and the results are negative, if the patient returned to the ED with chest pain again within a year or two, it wouldn’t be necessary to repeat the exam.

Avoids Cath Lab
Advocates of CCTA also say it prevents patients from undergoing unnecessary invasive procedures to determine whether they have coronary artery disease. ED patients may be sent to the cath lab when physicians suspect a blockage that could lead to a heart attack. Historically, only about one-third of patients without known heart disease who undergo elective cardiac catheterization are found to have obstructive coronary disease, Maroules says. “Although catheterization is generally safe, there are risks as with any invasive procedure. CCTA is showing promise as a gatekeeper to the cath lab,” he notes.

One of CCTA’s greatest strengths, Maroules says, is its negative predictive value. “What that means is if a low- or intermediate-risk patient comes to the ED complaining of chest pain and has a negative coronary CT angiogram, the likelihood of that patient having obstructive coronary artery disease is negligible,” he says. “So the [emergency] physician can confidently reassure the patient, ‘Your chest pain is not related to coronary disease, and you are not at immediate risk for a heart attack.’”

Yet another argument in favor of CCTA is that it reduces the likelihood of missing a patient who could have a myocardial infarction within 30 days, which could lead to a lawsuit. “Twenty percent of malpractice is caused by missed myocardial infarctions by the emergency room physicians,” Cury says. “There is strong data in the recent multicenter trials and other large trials that, even in patients with low- to intermediate-risk of acute coronary syndrome [ACS], negative cardiac enzymes, and negative EKG, 5% to 8% will have a final diagnosis of ACS. If you plan to discharge those patients with no tests, then they will come back with major adverse cardiac events [MACE] in 30 days. This is well-known since publications in The New England Journal of Medicine from Lee and colleagues back in 2000.”

Cury says risk stratification is the most important consideration. Patients with a very low risk of heart attack won’t need tests, he says. However, if the ED physician suspects a cardiac cause for the patient’s chest pain or atypical chest pain with low to intermediate risk of ACS and is not comfortable discharging him, then further workup with CCTA is warranted. “It has now been proven with at least three large randomized trials and other publications from large health care systems to improve efficiency of care, decrease length of stay, reduce downstream tests, and be a very safe strategy with no or minimal MACE events,” he says. “This is what we are looking for in medicine: to improve quality of care and the patient experience and to reduce costs.”

Strategic planning, coordination of care among specialties, and physician expertise in CCTA are imperative for a successful implementation of a CCTA program, Cury says.

The Argument Against
Redberg disagrees that there is evidence that CCTA reduces malpractice risk. “There is absolutely no data to suggest that ordering unnecessary tests protect physicians from lawsuits,” she says. “There is very little relationship between how good or how bad you practice medicine and whether you’re getting sued. The problem is that defensive medicine is used as a reason for a lot of unnecessary testing. It’s a claim that’s made frequently, but one that is very unsubstantiated.”

As a cardiologist, Redberg argues it’s better to send patients with non–high-risk chest pain and no other signs of a heart attack home and suggest they follow up with their doctor rather than to waste time sending them for a CCTA. Following up in the doctor’s office is a safer way to go and in the best interests of the majority of low-risk patients, she says. In addition, a cardiologist can learn a lot about a patient’s blood flow to his heart and prognosis by seeing how long he can walk on a treadmill.

Redberg also disagrees that CT is without risks. Patients can have adverse reactions to the contrast dye, and any unnecessary radiation exposure is too much, even if it is only 1 to 5 mSv.

Redberg says sending low-risk ED patients for CCTA increases the likelihood they will get more testing and interventions downstream, increasing their health care costs for no good reason. And while it is faster to obtain a cardiac CT scan than a stress test, it would be even faster to discharge low-risk patients without either or without any further test.

The question of whether ordering CCTA for low- to intermediate-risk patients presenting in the ED may come to a head when more provisions of the Affordable Care Act kick in at the start of the new year. Each year some 8 million people come to the ED complaining of chest pain. The number of people using the ED is expected to increase as more have health insurance.

Any hospital with a 64-slice scanner can perform coronary CT. Maroules expects that over the next several years, “We’ll see a surge in the use of CCTA throughout the country and the world. Programs throughout the world have caught on to CT angiography and integrating it into the ED will make a big impact on patient care and the management of acute chest pain.”

There’s a lot of caution around accepting CCTA, Rubin says. But, he adds, “I think it has a big, big future. It’s just taking a little while for us to get there.”

— Beth W. Orenstein of Northampton, Pennsylvania, is a freelance medical writer and regular contributor to Radiology Today.