Diagnostic performance and cost of CT angiography versus stress ECG — A randomized prospective study of suspected acute coronary syndrome chest pain in the emergency department (CT-COMPARE),☆☆

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Abstract

Background

Coronary CT angiography (CCTA) has high sensitivity, with 3 recent randomized trials favorably comparing CCTA to standard-of-care. Comparison to exercise stress ECG (ExECG), the most available and least expensive standard-of-care worldwide, has not been systematically tested.

Methods

CT-COMPARE was a randomized, single-center trial of low–intermediate risk chest pain subjects undergoing CCTA or ExECG after the first negative troponin. From March 2010 to April 2011, 562 patients randomized to either dual-source CCTA (n = 322) or ExECG (n = 240). Primary endpoints were diagnostic performance for ACS, and hospital cost at 30 days. Secondary endpoints were time-to-discharge, admission rates, and downstream resource utilization.

Results

ACS occurred in 24 (4%) patients. ExECG had 213 negative studies and 27 (26%) positive studies for ACS with sensitivity of 83% [95% CI: 36, 99.6%], specificity of 91% [CI: 86, 94%], and ROC AUC of 0.87 [CI: 0.70, 1]. CCTA (> 50% stenosis considered positive) had 288 negative studies and 18/35 (51%) positive studies with a sensitivity of 100% [CI: 81.5, 100], specificity of 94% [CI: 91.2, 96.7%], and ROC of 0.97 [CI: 0.92, 1.0; p = 0.2]. Despite CCTA having higher odds of downstream testing (OR 2.0), 30 day per-patient cost was significantly lower for CCTA ($2193 vs $2704, p < 0.001). Length of stay for CCTA was significantly reduced (13.5 h [95% CI: 11.2–15.7], ExECG 19.7 h [95% CI: 17.4–22.1], p < 0.0005), which drove the reduction in cost. No patient had post-discharge cardiovascular events at 30 days.

Conclusions

CCTA had improved diagnostic performance compared to ExECG, combined with 35% relative reduction in length-of-stay, and 20% reduction in hospital costs. These data lend further evidence that CCTA is useful as a first line assessment in emergency department chest pain.

Introduction

Chest pain is a common cause for presentations to hospital emergency departments (EDs). The clinical investigation of undifferentiated chest pain must include the expeditious assessment for acute coronary syndrome (ACS). Many chest pain assessment pathways include serial electrocardiography and biomarkers followed by a provocative stress test to rule out myocardial ischemia [1], [2]. In many institutions, treadmill exercise stress ECG (ExECG) is used to stratify intermediate risk patients due to the widespread availability and low cost, and is a Class IB indication in the AHA/ACC guidelines [3]. However, ExECG has relatively limited diagnostic performance with low sensitivity and specificity in unselected populations [4]. More recently, coronary computed tomographic angiography (CCTA) has been investigated as a rapid, noninvasive test with a high negative predictive value and reduced length of stay in low to intermediate risk patients with possible ACS [5], [6], [7]. These studies have suggested that CCTA-based care is also less expensive compared to provocative stress testing when coupled with imaging. However, cost analyses suggest that CCTA may be more expensive compared to ExECG-based care [8]. To date, there have been no large-scale clinical trials comparing CCTA-based care to ExECG-based care in possible ACS patients.

The CT Coronary Angiography Compared to Exercise ECG (CT-COMPARE) study was a prospective randomized trial that compared dual source CCTA with ExECG as part of the standard of care in low–intermediate risk possible ACS patients presenting to the ED. The primary endpoints were the diagnostic performance measures and the hospital-based costs of CCTA-based care as compared to ECG-based care.

Section snippets

Study design

CT-COMPARE was a randomized, prospective, non-blinded single-center study conducted in a large tertiary academic Australian hospital. Enrolled subjects were randomized to either CCTA or ExECG performed as part of an established chest pain assessment service [1], [9]. The local Human Research and Ethics Committee approved the study (HREC/09/QPCH/89) and all subjects were required to give informed consent prior to randomization. The study was registered with the Australian New Zealand Clinical

Results

From January 2010 to April 2011, 717 low-to-intermediate risk patients with chest pain were enrolled in the study in a 1:1 ratio. Sixty one patients (8%) were subsequently excluded prior to testing due to not meeting strict enrolment criteria (Fig. 1). Eighty four patients (11%) were excluded at completion of the trial in consultation with the Human Research Ethics Committee due to misplacement of informed consent documentation. Data for included and secondarily excluded patients were compared

Discussion

For subjects presenting to the ED with acute chest pain, CCTA had better positive predictive value than ExECG, combined with a significantly reduced length of stay and reduced per-patient cost.

In an outpatient population, CCTA has emerged as an accurate and rapid tool for the exclusion of coronary artery disease [15], [16], [17], [18], [19]. Recent randomized controlled trials in acute ED patients that compared CCTA to nuclear SPECT [7], or to a mixed standard-of-care [5], [6] showed lower

Limitations

Limitations of this study need to be addressed. First, of the 21% of eligible patients not enrolled, 11% had misplaced informed consent primarily due to loss of paper documentation during patient transfers. This resulted in a disproportionate exclusion of patients in the ExECG group. An analysis between these excluded and study patients show no meaningful differences between baseline data (clearly outlined in Appendix 2), but primary outcomes could be affected if their data were included in the

Conclusions

In symptomatic patients at low–intermediate risk for acute coronary syndrome presenting to the emergency department, coronary CT angiography is faster and less expensive, with improved diagnostic performance compared to exercise treadmill ECG-based care. These data add additional proof that protocols using CCTA rather than stress testing-based care in emergency departments should be considered. Further verification of these data in a multicenter randomized trial is warranted.

Acknowledgments

We thank the staff of the Prince Charles Hospital Medical Imaging Department, Liz Warburton, Steve Graves, Kathryn Arnett, and our patients.

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Funding: The study was supported by grants from 1) the Queensland Emergency Medicine Research Foundation (#QEMRF-EMSS-2009-022), 2) the Smart Futures Fellowship Early Career Grant (Queensland State Government #ISF783), 3) the Washington–Queensland Trans-Pacific Fellowship fund and 4) Grant Number 5KL2RR025015-02 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH) and NIH Roadmap for Medical Research. The grant bodies had no input on study design, data analysis or writing.

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No conflicts of interest or relationships with industry.

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