Coronary Computed Tomographic Angiography in the Evaluation of Low-Risk Patients with Acute Chest Pain
Background: Emergency room visits for evaluation of acute chest pain are common. After acute coronary syndromes are excluded and coronary artery disease is suspected, patient evaluation is generally indicated. Non-invasive testing prior to discharge, or soon after, is a practicable approach used to exclude the presence of clinically significant disease. Given its high negative prognostic value and quickly obtained, coronary CTA has been proposed as an attractive approach in this setting.
Objective: The objective of this Assessment is to compare the net health outcome following a coronary CTA diagnostic strategy to other commonly used strategies for evaluating patients with acute chest pain presenting to the emergency room found not to have evidence of acute coronary syndromes.
Search strategy: Randomized controlled trials and prospective observational studies reporting prognosis were identified by searching the MEDLINE® (via PubMed) database through May 2011. Anticipating CT-STAT publication, preliminary reports of results from that trial were also included.*
Selection criteria: Randomized controlled trials conducted in the samples of the target population were included. Prospective observational studies including more than 100 patients reporting prognostic value of coronary CTA were in also reviewed.
Main results: Two randomized, controlled trials and 2 prognostic studies were identified. The first trial evaluated 197 randomized patients from a single center without evidence of acute coronary syndromes to coronary CTA (n=99) or usual care (n=98). Over 6 months’ follow-up, no cardiac events occurred in either arm. Invasive coronary angiography rates were somewhat higher in the coronary CTA arm (12.1% versus 7.1%). Diagnosis was achieved more quickly following coronary CTA. The second trial (CT-STAT) evaluated a similar sample of 699 randomized patients from 16 centers—361 undergoing coronary CTA and 338 undergoing myocardial perfusion imaging. Over 6 months’ follow-up, there were no deaths in either arm, 2 cardiac events in the coronary CTA arm, and 1 in the perfusion imaging arm. Invasive coronary angiography rates were similar in both arms (7.2% after coronary CTA; 6.5% after perfusion imaging). A second noninvasive test was obtained more often following coronary CTA (10.2% versus 2.1%), but cumulative radiation exposure in the coronary CTA arm (using retrospective gating) was significantly lower—mean 11.5 versus 12.8 mSv. Time to diagnosis was shorter (mean 3.3 hours) and estimated emergency room costs lower with coronary CTA.
Two studies of patients from the target population reported no cardiac events following a negative coronary CTA after 12 months’ (n=481) and 24 months’ (n=368) follow-up.
Author’s Conclusions and Comments: Owing to the negative prognostic value of coronary CTA in this population, the test offers an alternative for patients and providers. Evidence obtained in the emergency setting, similar to more extensive results among ambulatory patients, a normal coronary CTA appears to provide a prognosis as good as other noninvasive tests. Other important outcomes that need be considered in comparing technologies include invasive coronary angiography rates, use of a second noninvasive test, radiation exposure, and follow-up of any incidental lung findings. While there is uncertainty accompanying the limited trial evidence, it is reasonable to conclude that the invasive angiography rate following coronary CTA is similar to that following perfusion imaging. Evidence regarding comparative differences in obtaining a second noninvasive test is limited to CT-STAT and was greater following coronary CTA. Despite that difference, cumulative radiation exposure remained lower in the coronary CTA arm utilizing retrospective gating techniques. Given further reduction realized with prospective gating, radiation exposure accompanying coronary CTA will continue to decrease. Incidental findings following coronary CTA are common and lead to further testing without evidence for benefit.
While uncertainties exist and should be further studied, considering important outcomes in the patient population, the net health outcome following coronary CTA appears to be as good as that following other strategies.
Based on the available evidence, the Blue Cross and Blue Shield Association Medical Advisory Panel (MAP) made the following judgments about coronary CTA for patients with acute chest pain presenting to the emergency room and found not to have evidence of acute coronary syndromes.
1. The technology must have final approval from the appropriate governmental regulatory bodies.
Coronary CTA is performed using multidetector-row CT (MDCT) and multiple manufacturers have received U.S. Food and Drug Administration (FDA) 510(k) clearance to market machines. Current machines are equipped with at least 64 detector rows. Intravenous iodinated contrast agents used for coronary CTA have also received FDA approval.
2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes.
For patients with acute chest pain presenting to the emergency room found not to have evidence of acute coronary syndromes, there is sufficient evidence to permit conclusions concerning the effect of coronary CTA on relevant health outcomes.
3. The technology must improve the net health outcome.
4. The technology must be as beneficial as any established alternatives.
By avoiding adverse cardiac events, use of coronary CTA in the target population will improve the net health outcome and as well as other strategies currently used in practice.
5. The improvement must be attainable outside the investigational settings.
Coronary CTA is widely available and used outside the investigational setting. The main clinical trial evaluating its use was performed primarily in real-world settings.
Based on the above, for patients with acute chest pain presenting to the emergency room without history of coronary artery disease and found not to have evidence of acute coronary syndromes, coronary CTA meets the TEC criteria.
*This trial was published as the Assessment was in press (Goldstein JA, Chinnaiyan KM, Abidov A et al.; CT-STAT Investigators. (2011). The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) Trial. J Am Coll Cardiol, 58(14):1414-22). The final report will be updated with the final, published results of this trial.
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NOTICE OF PURPOSE: TEC Assessments are scientific opinions, provided solely for informational purposes. TEC Assessments should not be construed to suggest that the Blue Cross Blue Shield Association, Kaiser Permanente Medical Care Program or the TEC Program recommends, advocates, requires, encourages, or discourages any particular treatment, procedure, or service; any particular course of treatment, procedure, or service; or the payment or non-payment of the technology or technologies evaluated.
