Admission rates are high among patients presenting to emergency departments (ED) with possible acute coronary syndromes (ACS), although for most of these patients, the symptoms are ultimately found not to have a cardiac cause. This is true despite the introduction of clinical decision rules and the improved sensitivity of cardiac markers.

The absence of evidence of coronary disease on invasive coronary angiography is associated with a low risk of future cardiac events. Coronary computed tomographic angiography (CCTA) is a noninvasive test, and evidence suggests that the rate of cardiac events among patients with minimal or no CAD is very low. However, these studies were not large enough to clarify whether a CCTA-based strategy, compared with traditional approaches, allows the safe discharge of patients after a negative test.

Investigators conducted a trial to determine the safety and efficiency of a CCTA-based strategy. The study (known as ACRIN PA 4005) was funded in part by the American College of Radiology Imaging Network (ACRIN) Foundation and the Pennsylvania Department of Health.

Harold Litt, MD, PhD, and colleagues enrolled 1,370 patients: 908 in the CCTA group and 462 in the group receiving traditional care. Of 640 patients with a negative CCTA examination, none died or had a myocardial infarction within 30 days (0%; 95% CI 0–0.57).¹ Compared to those receiving traditional care, patients in the CCTA group had a higher rate of discharge from the ED (49.6% vs. 22.7%; 95% CI 21.4–32.2), a shorter length of stay (median = 18.0 hours vs. 24.8 hours; p < 0.001), and a higher rate of detection of coronary disease (9.0% vs. 3.5%; 95% CI 0–11.2). There was one serious adverse event in each group.

At ACC.13, Judd E. Hollander, MD, presented 1-year outcomes and resource utilization data. In the year following discharge, there was no increase in resource utilization in terms of diagnostic testing for CAD, use of echocardiography, or medication use. However, the resources did seem to be applied more appropriately, said Dr. Hollander, since patients were more likely to have a determination of underlying disease.

In the same issue of the New England Journal of Medicine that included the ACRIN PA 4005 results, another group reported the results of the Rule Out Myocardial Infarction Using Computer Assisted Tomography II (ROMICAT II) trial.² In this study, 1,000 patients were randomly assigned to either CCTA or standard diagnostic procedures, which were performed at the discretion of the physicians in the ED.

Compared to standard evaluation, for those undergoing early CCTA the mean length of stay in the hospital was reduced by 7.6 hours (p < 0.001) and more patients were discharged directly from the emergency department (47% vs. 12%; p < 0.001). There was no undetected ACS and no significant differences in major adverse cardiovascular events at 28 days. After CCTA, there was more downstream testing and higher radiation exposure. The cumulative mean cost of care was similar in the CCTA group and the standard-evaluation group ($4,289 and $4,060, respectively; p = 0.65).

Is Any Test Necessary at All?

In an accompanying editorial, Rita Redberg, MD, noted that the underlying assumption of the ACRIN PA 4005 and ROMICAT II studies is that some diagnostic test must be performed before discharging these low- to intermediate-risk patients from the ED, an assumption she suggests is unproven and probably unwarranted.³ “The rationale for any test, as compared with no testing, should be that it will lead to an improved outcome, and here there is no evidence that the tests performed led to improved outcomes,” Dr. Redberg wrote. “Indeed, event rates for major adverse cardiac events among all patients in the studies by Hoffmann et al. and Litt et al. were so low ... that it is impossible to know whether the CCTA groups received any benefit whatsoever.”

Of course, many of the patients studied likely would not have been sent home but rather admitted for “rule out”—or, as one interventionalist put it, to avoid the liability of a patient discharged from the ED who experiences sudden cardiac death in the parking lot on their way home.

At ACC.13, Dr. Litt said, “A negative coronary CT means that you can safely discharge someone. Having a technique that can efficiently triage these patients into ones that can be discharged quickly and ones who need further evaluation is very important.” Increased rates of discharge and a reduced length of stay make this strategy more efficient, he said, than traditional care.

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References

1. Litt HI, Gatsonis C, Snyder B, et al. N Engl J Med. 2012;366:1393-403.
2. Hoffmann U, Truong QA, Schoenfeld DA, et al. N Engl J Med. 2012;367:299-308.
3. Redberg RF. N Engl J Med. 2012;367:375-6.

To listen to an interview with Judd E. Hollander, MD, about the CCTA rule-out strategy, visit youtube.cswnews.org. The interview was conducted by Patricia A. Pellikka, MD.

Keywords: Myocardial Infarction, Acute Coronary Syndrome, Diagnostic Tests, Routine, Coronary Angiography, Tomography, Death, Sudden, Cardiac, United States, Echocardiography, Triage

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