• Myocardial Infarction
• Imaging Modalities
• Emergency Radiology Clinical Trials
• Cardiac Imaging Techniques

Coronary computed tomographic angiography (CCTA) is a noninvasive test with a very high negative predictive value for the detection of coronary artery disease (CAD) [Janne d'Othee B et al. Eur J Radiol 2008]. It has the potential to safely expedite discharge or admission of potential acute coronary syndrome (ACS) patients who present in emergency departments (EDs); yet, a lack of sufficient data has kept the approach from widespread use.

Harold Litt, MD, PhD, University of Pennsylvania, Philadelphia, Pennsylvania, USA, presented results from the CT Coronary Angiogram Versus Traditional Care in Emergency Department Assessment of Potential ACS Trial [Litt HI et al. N Engl J Med 2012] to determine the safety and efficacy of a CCTA–based strategy compared with traditional ED approaches.

This Phase 4 randomized, controlled, multicenter trial was conducted by the American College of Radiology Imaging Network (ACRIN) and compared CCTA–based strategy with traditional “rule out” approaches for low–to–intermediate–risk patients with chest pain and possible ACS.

The primary hypothesis was that those patients without clinically significant CAD by CCTA (ie, no coronary artery stenosis ≥50%) will have <1% rate of 30–day cardiac death or myocardial infarction (MI). Secondary aims were to compare CCTA with traditional care with respect to ED discharge rate and length of stay (LOS); 30–day major adverse cardiac event and revascularization; and 30–day resource utilization (Table 1).

Eligibility criteria included patients aged >30 years with signs/symptoms of potential ACS; TIMI score 0 to 2; no acute ischemia on electrocardiogram (ECG); and a need for admission or testing to exclude ACS. CCTA was performed with a 64–slice or greater multidetector CT scanner that could be used to perform ECG–synchronized cardiac studies.

A total of 1370 low–to–intermediate–risk patients who presented with possible ACS were randomized in a 2:1 ratio to undergo CCTA (n=908) or traditional care (n=462). Baseline characteristics were similar; mean age was 50 years, and 60% of patients were black. Of patients who were randomized to CT, 16% could not receive the CT (27% due to elevated heart rate).

Of 640 patients with a negative CCTA examination, none died or had an MI within 30 days (0%; 95% CI, 0 to 0.57%). Compared with the traditional care group, those who received CCTA had a higher rate of discharge from the ED (49.6% vs 22.7%; absolute difference, 26.8%; 95% CI, 21.4 to 32.2%), a shorter LOS (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%; difference 5.6 percentage points; 95% CI, 0 to 11.2). Numerically, more CCTA patients were diagnosed with CAD (9.0 vs 3.5%; 95% CI, 0 to 11.2). One serious adverse event took place in each group (bradycardia which was determined to be related to medication for heart rate control). No significant differences in 30–day resource use (CCTA vs traditional care) were observed (Table 2).

Dr. Litt noted that this trial had a wider range of traditional care and “real world” management and disposition of patients, but the results only applied to low–to–intermediate–risk individuals. He concluded that a CCTA–first strategy for low–intermediate–risk potential ACS patients was safe and efficient, with increased ED discharge rates and reduced LOS. Larger randomized controlled trials are needed, as well as long–term follow–up on resource use and effects of CAD diagnosis on outcomes.

• © 2012 MD Conference Express®