Coronary CTA Use in Emergency Department Saves Time, Money

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Using coronary computed tomographic angiography (CTA) as a screening tool for low-risk patients with chest pain in the emergency department achieves lower costs and faster diagnoses compared with myocardial perfusion imaging but does not sacrifice safety or accuracy, according to results of a randomized trial appearing in the September 27, 2011, issue of the Journal of the American College of Cardiology.

Findings from the CT-STAT (Computed Tomographic angiography for Systemic Triage of Acute chest pain patients to Treatment) trial were first presented in November 2009 at the annual American Heart Association (AHA) Scientific Sessions in Orlando, FL.

For the trial, researchers led by Gilbert L. Raff, MD, of William Beaumont Hospital (Royal Oak, MI), randomized 699 patients with low-risk acute chest pain (TIMI risk score ≤ 4; normal initial ECG and cardiac enzymes) to standard nuclear stress imaging or coronary CTA as an initial screen at 16 different emergency departments between June 2007 and November 2008.

Both groups had substantial portions of patients ruled out from having significant CAD (82.2% with CTA, 89.9% with nuclear stress imaging). In addition, 24 patients (6.7%) were referred for invasive coronary angiography after CTA, with 13 (3.6%) receiving subsequent revascularization (4 CABG, 9 PCI). After nuclear stress imaging, 21 patients (6.2%) went on to coronary angiography (P = 0.8 compared with CTA), with 8 (2.4%) subsequently receiving revascularization (8 PCI, 0 CABG; P = 0.34 compared with CTA with regard to total revascularizations). There were no CABG procedures in the stress imaging arm.

At 6 months, patients showed similar rates of procedures and adverse events regardless of whether they were first screened with CTA or stress imaging (table 1).

Table 1. Six-Month Cumulative Outcomes

CTA resulted in a lower median effective radiation dose compared with nuclear stress imaging (11.5 mSv vs. 12.8 mSv; P = 0.02). CTA also reduced median time to diagnosis, the primary endpoint, by 54% and total emergency department costs by 38.2%, while the rates of MACE (ACS, cardiac death, or revascularization) remained equivalent at 6 months.

Table 2. Six-Month Efficiency, Cost, and Safety Outcomes

Actual testing costs were similar between CTA ($507) and nuclear stress imaging ($538). There were no deaths in either group.

From the data, the authors conclude that for low-risk acute chest pain patients, “a diagnostic approach employing [coronary CTA] as the primary noninvasive imaging modality . . . facilitates more rapid evaluation compared with a strategy utilizing rest-stress [myocardial perfusion imaging] and is associated with lower total [emergency department] costs.”

Dr. Raff and colleagues note that the cost benefits of coronary CTA as an initial screen, along with the lower radiation burden and similar safety compared with stress imaging, “could potentially reduce the onerous health care resource burden of this common, expensive clinical scenario [of acute low-risk chest pain] in appropriately selected patients.”

CTA Not Supported in Recent Guidelines

However, the investigators caution that many emergency departments do not use stress perfusion imaging as the standard of care for low-risk patients without prior CAD. Coronary CTA also should first be compared with other alternatives such as ECG stress testing, stress echocardiography, or myocardial perfusion based on rest-only or stress-only imaging before definitive conclusions can be made, they say.

Findings from the CT-STAT trial were not published in time to be included in recent AHA guidelines that recommend exercise treadmill testing without imaging as the initial test in low- to intermediate-risk patients who present with ischemic symptoms. Those recommendations support nuclear stress testing as an accurate way to increase both diagnostic and prognostic information beyond ECG testing and clinical variables, while CTA is discussed but not supported in low-risk patients.

In an accompanying editorial, Michael Salerno, MD, PhD, Jamieson M. Bourque, MD, MS, and George A. Beller, MD, all of the University of Virginia (Charlottesville, VA), note that “the CT-STAT trial provides additional evidence for the excellent [negative predictive value] of [coronary] CTA in patients at low risk for an ACS or at low-intermediate risk of having CAD as the cause of the chest pain syndrome. . . . ”

Future Trial PROMISEs More Definitive Answer

However, Dr, Salerno and colleagues point out that a “substantial number of patients presenting with chest pain in the [emergency department] . . . are not eligible for [coronary] CTA or would benefit more from a functional imaging approach.”

They agree with the AHA guidelines that exercise ECG testing alone is the most cost-effective option for first-line testing, with no imaging at all “for patients with atypical chest pain, patients with a normal resting ECG, and patients who attain high exercise heart rates and workloads without associated ischemic ST-segment depression.”

The editorial notes that the true difference in cost and time to diagnosis between coronary CTA and myocardial stress perfusion imaging will come from future studies such as the PROMISE (PROspective Multicenter Imaging Study for Evaluation of chest pain) trial, which will compare improved, state-of-the-art versions of both technologies.

 

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Sources:
1. Goldstein JA, Chinnaiyan KM, Abidov A, et al. The CT-STAT (coronary computed tomographic angiography for systemic triage of acute chest pain patients to treatment) trial. J Am Coll Cardiol. 2011;58:1414-1422.

2. Salerno M, Bourque JM, Beller GA. Coronary angiographic evaluation of low-risk chest pain in the emergency department: CT-STAT, or maybe not quite that fast? J Am Coll Cardiol. 2011;58:1423-1425.

 

 

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