hs-Troponins Rival Coronary CT For Spotting Significant CAD: BEACON

Marlene Busko

November 25, 2015

ORLANDO, FL — Among patients with suspected acute coronary syndrome (ACS) seen in emergency rooms in the Netherlands, coronary CT angiography (CCTA) did not lead to better detection of significant CAD compared with standard optimal care that included high-sensitivity (hs) troponin tests in a new study[1].

Moreover, CCTA did not lead to more patients being discharged from the emergency department or patients staying there for a shorter time in the Better Evaluation of Acute Chest Pain With Computed Tomography Angiography (BEACON) study, unlike in the American College of Radiology Imaging Network/Pennsylvania Department of Health (ACRIN/PA) or Rule Out Myocardial Infarction Using Computer Assisted Tomography II (ROMICAT II) studies.

BEACON compared CCTA vs standard care encompassing hs-troponin testing to see which was better at detecting significant CAD, as measured by the number of patients requiring revascularization within 30 days.

Although hs-troponin tests have not yet been approved in the US, these tests have been available in Europe since 2012, where they are widely used, and are "very fast and very accurate," said Dr Admir Dedic (Erasmus University Medical Center, Rotterdam, the Netherlands), presenting the study findings at the American Heart Association (AHA) 2015 Scientific Sessions.

"We think that hs-troponins have a very big role in [these results]," he continued. "They identify high-risk patients who do not have a very favorable prognosis in the first 30 days."

On the other hand, "I still think [CCTA] is an attractive option, because if you perform the test immediately, you will get less outpatient testing and lower medical costs," Dedic stressed. "If you are very good at performing CCTA [and minimizing radiation exposure], it's a good option to do it right away in the emergency department."

CCTA Led to Faster Discharge in Earlier Studies

Low- to intermediate-risk patients who arrive at an emergency department with acute chest pain pose a "diagnostic dilemma . . . [because] we are still afraid to miss an MI, but we don't want to be testing everybody," Dedic said.

Coronary CT angiography is noninvasive and allows a clinician to visualize CAD very accurately within minutes, and observational studies showed it had a high sensitivity and specificity for diagnosing ACS, he added. And in two randomized controlled US trials published in the New England Journal of Medicine in 2012, ACRIN-PA and ROMICAT II, CCTA led to a "dramatic" decrease in length of stay and a large increase in the number of patients who could be discharged from the emergency department, he noted.

The researchers aimed to compare the clinical effectiveness of early CCTA vs contemporary standard care including hs-troponin tests, as determined by the treating physicians.

BEACON randomized 500 patients with symptoms suggestive of ACS at the emergency departments of five community hospitals and two university hospitals. Most hospitals used a Roche assay to measure hs-troponin.

Patients were excluded if they had a clear noncardiac condition, history of ACS (or coronary revascularization), needed urgent cardiac catheterization, or were pregnant.

Patients were a mean age of 54 years, and 47% were women. Most had a low Thrombolysis in Myocardial Infarction (TIMI) risk score, and about one-fifth had ECG abnormalities that could represent ischemia.

No CAD-Identification Advantage With CCTA in hs-Troponin Era

CCTA identified 22 of 250 patients (9%) with significant CAD requiring coronary revascularization within 30 days, and standard care identified this in 17 of 250 patients (7%; P=0.40).

A similar percentage of patients were discharged from the emergency department in the CCTA and optimal standard-care groups (65% vs 59%; P=0.16). Patients in both groups were discharged from the emergency department after a mean 6.3 hours. These differences from ACRIN/PA and ROMICAT II are likely partly because of differences in healthcare insurance coverage and medical liability between the US and the Netherlands, Dedic suggested.

The current study also showed that patients in the CCTA group had lower direct medical costs (€337 vs €511; P<0.01) and were less likely to have outpatient testing (10 patients [4%] vs 26 patients [10%]; P<0.01).

There was no difference in the incidence of undetected ACS.

Thus, "a diagnostic strategy supplemented by early CCTA is safe, less expensive, and averts outpatient testing," Dedic and colleagues summarize. "However, in the era of hs-troponins, CCTA does not identify more patients with significant CAD requiring coronary revascularization, nor does CCTA shorten hospital stay or allow for more direct discharge from the emergency department."

Concerns and Future Directions

Session comoderator Dr W Brian Gibler (University of Cincinnati, OH) and an audience member mentioned a few potential stumbling blocks to using CCTA in this setting. Gibler noted that the study excluded evenings and weekends, and extending protocols to cover all hours "has been a problem in the United States."

An audience member added that there could be disagreements between hospital radiologists and cardiologists over reimbursement issues, and some cardiologists might be resistant to using CCTA because they derive "bread-and-butter" income from exercise stress tests (which would not be required after a negative CCTA).

Dedic said that more research is needed to determine how early CCTA affects hard end points, whether CCTA should be performed if a patient has slightly elevated hs-troponin, how newer techniques such as fractional flow reserve derived from coronary CT angiography (FFR-CT) perform in this setting, and the effect of round-the-clock diagnostic tests.

The study authors have no relevant financial relationships. Gibler reports ownership interest in MyoCardioCare and Entegrion. He is a consultant/on the advisory board for Medscape, AstraZeneca, and Janssen.


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