Clinical Benefits of Coronary Computed Tomography Angiography for Evaluating Low-Risk Patients With Non-ST-Elevation Acute Coronary Syndrome in the Emergency Department　― Systematic Review and Meta-Analysis ―

Abstract

Background

The utility of coronary computed tomography angiography (CCTA) in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS), particularly among low-risk individuals presenting to the emergency department (ED), remains unclear. We conducted a systematic review to assess the clinical benefits of CCTA in low-risk patients presenting to the ED with chest pain.

Methods and Results

A systematic search of MEDLINE, CENTRAL, and Web of Science was performed for randomized controlled trials (RCTs) published up to March 23, 2023, comparing CCTA performed in the ED with standard care in low-risk patients with NSTE-ACS. Low-risk status was defined as resolved symptoms at ED presentation and no troponin elevation or ischemic ECG changes. Seven RCTs were extracted from the databases. No significant differences were observed between the CCTA and standard care groups in all-cause mortality, non-fatal myocardial infarction, ED revisits, or radiation exposure. However, hospital length of stay was significantly shorter and healthcare costs were slightly lower in the CCTA group. Conversely, revascularization and invasive coronary angiography were significantly more frequent in this group.

Conclusions

In low-risk patients with NSTE-ACS, CCTA performed in the ED did not reduce adverse clinical events but was associated with shorter hospital stays and marginally reduced healthcare costs. These findings suggest that CCTA may be a useful tool that supports the safe and early discharge of selected patients.

Despite significant advances in cardiovascular care, acute coronary syndrome (ACS) remains a leading cause of mortality worldwide.^1–5 Given that non-ST-elevation acute coronary syndrome (NSTE-ACS) encompasses a wide spectrum of clinical severity, risk stratification using serial troponin measurements and electrocardiographic findings is essential to determine the necessity and optimal timing of an invasive approach.^6–8 Patients suspected with NSTE-ACS and classified as low-risk, characterized by resolved symptoms, normal troponin levels, and no significant ECG changes, are managed electively, similar to patients with chronic coronary syndrome.^6–8 However, a subset of these patients may have underlying unstable angina, and non-invasive CCTA may prevent missed diagnoses in this group.^9,10 Although previous systematic reviews have evaluated the benefit of CCTA in low-to-intermediate risk patients,^11–13 none have specifically addressed its utility in low-risk patients with NSTE-ACS.

Accordingly, the Japanese Resuscitation Council (JRC) ACS Task Force for the JRC Guidelines 2025 performed this systematic review to assess if early CCTA performed in the emergency department (ED) is beneficial for patients with low-risk NSTE-ACS.

Methods

The JRC ACS Task Force was established through a collaboration between the Japanese Circulation Society and the Japanese Society of Internal Medicine. Following discussions with the Guidelines Editorial Committee, the Population, Intervention, Comparator, Outcome, Study design, and Time frame (PICOST) framework was adopted to guide the systematic review as follows:

P (population): Adult patients (aged ≥18 years) presenting to the ED classified as low risk with suspected ACS.

I (interventions): CCTA performed in the ED.

C (comparators, controls): No CCTA performed in the ED.

O (outcomes): All-cause mortality, non-fatal myocardial infarction, length of hospital stay, revascularization, invasive coronary angiography, revisit to the ED, radiation exposure, and healthcare costs. All-cause mortality and non-fatal myocardial infarction were considered critical outcomes, while length of hospital stay, revascularization, invasive coronary angiography, revisit to the ED, radiation exposure, and healthcare costs were considered important outcomes.

S (study design): Only randomized controlled trials (RCTs) published in English were included; review articles were excluded.

T (time frame): All literature published up to March 23, 2023.

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with the International Prospective Register of Systematic Reviews (PROSPERO; ID CRD42023402105).^14,15

Search Strategies

The literature search strategy was developed using Medical Subject Headings (MeSH) terms and relevant keywords related to NSTE-ACS, CCTA, and ED presentations. The complete search strategy is detailed in Supplementary Table. A comprehensive search of MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science was conducted to identify relevant studies published from database inception through to March 23, 2023. We included all full-text human studies published in English prior to this date.

Study Selection and Definitions

The study population consisted of adult patients with NSTE-ACS who underwent CCTA in an emergency setting. No restrictions were placed on the country of origin; however, only studies published in English were included. Studies were considered eligible if they met the following criteria: (1) RCT design; (2) inclusion of patients diagnosed with NSTE-ACS who were classified as low-risk; and (3) comparison of ED CCTA with standard of care. Low-risk patients were defined as those whose symptoms had resolved at the time of ED presentation, with no troponin elevation or ischemic electrocardiographic changes.

Data Extraction and Management

The following data were extracted: author name(s), article title, journal name, year of publication, website URL, and abstract. After removing duplicates, study titles and abstracts were independently screened by 2 reviewers (K.T., R.A.) based on the predefined inclusion criteria. In cases of uncertainty, the full texts were independently assessed by the same 2 reviewers. Discrepancies regarding study inclusion or exclusion were resolved through discussion, with final adjudication by a third independent reviewer (T. Mano).

Assessment of the Risk of Bias

The risk of bias for each study and outcome was assessed using the Cochrane Risk of Bias 2 (RoB 2) tool.¹⁶ RoB 2 evaluates bias across 5 domains: (1) bias arising from the randomization process; (2) bias due to deviations from the intended intervention; (3) bias due to missing outcome data; (4) bias in the measurement of outcomes; and (5) bias in the selection of the reported result. Each domain is rated as having a ‘low risk,’ ‘high risk,’ or ‘some concerns’ regarding bias. Two experienced reviewers (K.T., R.A.) independently assessed the risk of bias for all included studies. A domain was rated as ‘high risk’ if the bias was present and likely to affect the outcome, and as ‘low risk’ if the bias was absent or present but unlikely to influence the result.

Rating Certainty of Evidence

The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was applied to assess the certainty of evidence regarding the potential benefits of emergent CCTA in patients with low-risk NSTE-ACS.^17,18 The certainty of evidence was rated as ‘high’, ‘moderate’, ‘low,’ or ‘very low’ based on the following domains: risk of bias, inconsistency, indirectness, imprecision, and publication bias.

Statistical Analysis

The results were synthesized using a random-effects model to account for between-study variability and to facilitate the pooling of estimated treatment effects. Dichotomous outcomes are reported as risk ratios (RRs), while continuous outcomes are expressed as mean differences (MDs) or ratio of means with corresponding 95% confidence intervals (CIs), as appropriate. Heterogeneity across studies for each outcome was assessed using the I² statistic to quantify inconsistency and was considered substantial if the source of heterogeneity could not be identified and the I² value was ≥50%.¹⁹ Currency conversion was performed using the following exchange rates: AU$1=US$0.96 and €1=US$1.30. A funnel plot was constructed to evaluate potential publication bias. All statistical analyses were performed using Review Manager (RevMan) version 5.4 or Stata version 15.1 (StataCorp LLC, College Station, TX, USA).

Results

Literature Search

Figure 1 shows a flow diagram of the study adapted from the PRISMA statement.^14,15 We identified 4,013 studies in PubMed, Web of Science, and Cochrane Library databases. Thirty studies were assessed for eligibility based on title and abstract screening. The full-text review led to the exclusion of 23 studies due to incorrect population (n=7), duplication of data from other included studies (n=7), inappropriate comparator (n=2), ineligible study design (n=3), inappropriate intervention (n=1), and irrelevant outcome (n=3). Finally, a meta-analysis was conducted on 7 RCTs comparing CCTA in the ED with the standard of care in patients with NSTE-ACS.

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart. The PRISMA flowchart illustrates the study selection process, including identification, screening, eligibility assessment, and inclusion.

Study Characteristics

Seven studies were included in the analysis, with a total of 3,648 patients. The characteristics of the included studies are summarized in Table 1.

Table 1.

Main Characteristics of the Included Studies

Study author (year)	Study design	No. participants	Intervention details	Follow up	Primary endpoint results	Main secondary endpoint results
Goldstein et al. (2007)20	RCT	197	Patients with recent chest pain and negative ECG and troponin were randomized to MSCT or standard care	6 months	No test complications, unstable angina, MI, or death occurred in either group	MSCT reduced time to diagnosis (3.4 vs. 15.0 h) and costs ($1,586 vs. $1,872; both P=0.001), with fewer repeat evaluations (2.0% vs. 7%; P=0.10)
Goldstein et al. (2011)21 (CT-STAT trial)	RCT	699	Patients with normal/non-diagnostic ECG and negative troponin were randomized to CCTA or MPI	6 months	CCTA reduced time to diagnosis by 54% vs. MPI (median 2.9 vs. 6.3 h; P<0.0001)	No significant difference in MACE after normal testing (0.8% CCTA vs. 0.4% MPI; P=0.29)
Hamilton-Craig et al. (2014; CT-COMPARE trial)22	RCT	562	Patients with chest pain and an initial negative troponin were randomized to CCTA or standard care	12 months	CCTA showed higher diagnostic accuracy for ACS (sensitivity 100%; specificity 94%; AUC 0.97) than ExECG (sensitivity 83%; specificity 91%; AUC 0.87), with lower 30-day cost per patient ($2,193 vs. $2,704; P<0.001)	CCTA significantly reduced length of stay (13.5 vs. 19.7 h; P<0.0005) and no post-discharge cardiovascular events occurred at 30 days
Hoffmann et al. (2012; ROMICAT-II trial)23	RCT	1,000	Patients with suspected ACS, normal ECG, and negative initial troponin were randomized to early CCTA or standard ED evaluation	28 days	Early CCTA reduced hospital stay by 7.6 h and increased direct ED discharge (47% vs. 12%; both P<0.001)	There were no undetected ACS and no significant differences in MACE at 28 days
Linde et al. (2015; CATCH trial)24	RCT	578	Patients with acute chest pain, normal ECG and troponin, were randomized to CCTA or standard care (exercise ECG or perfusion imaging)	19 months	Composite of MACE and chest pain-related readmission occurred in 11% of the CCTA group vs. 16% in the standard care group (HR 0.62; 95% CI 0.40, 0.98; P=0.04)	MACE (cardiac death, MI, UAP, late revascularization) occurred in 5 patients in the CCTA group vs. 14 in the standard care group (HR 0.36; 95% CI 0.16, 0.95; P=0.04)
Uretsky et al. (2017; PERFECT trial)25	RCT	411	Chest pain patients with negative troponin and non-diagnostic ECG requiring admission were randomized to CCTA or stress testing (echo or SPECT MPI)	1 year	No differences in discharge time, medication use, downstream testing, or CV hospitalizations at 1 year, but invasive angiography (11% vs. 2%; P=0.001) and PCI (6% vs. 0%; P<0.001) were more frequent in the CCTA group	No deaths occurred; MI (1 vs. 2) and unstable angina (1 case in CCTA group) were rare; downstream testing was more frequent in the CCTA group (P=0.06), but event and rehospitalization rates were similar
Piñeiro-Portela et al. (2021)26	RCT	203	ED patients with suspected ACS, non-diagnostic ECG, and negative cardiac markers were randomized to SE or MCT	5 years	No significant difference in the primary endpoint (death, MI, revascularization, readmission; 42% vs. 41%; P=0.91)	Overall cost was similar, but lower with negative SE vs. negative MCT (€557 vs. €706; P<0.02)

ACS, acute coronary syndrome; AUC, area under the curve; CCTA, coronary computed tomography angiography; CI, confidence interval; CV, cardiovascular; ECG, electrocardiogram; ED, emergency department; ExECG, exercise electrocardiogram; HR, hazard ratio; MACE, major adverse cardiac events; MCT, multidetector computed tomography; MI, myocardial infarction; MPI, myocardial perfusion imaging; MSCT, multislice computed tomography; PCI, percutaneous coronary intervention; RCT, randomized controlled trial; SE, stress echocardiography; SPECT, single photon emission computed tomography; UAP, unstable angina pectoris.

Goldstein et al. conducted a randomized trial comparing multislice computed tomography (MSCT) with standard of care in 197 low-risk patients with chest pain. They found that MSCT was equally safe, provided a definitive diagnosis in 75% of cases, and significantly reduced diagnostic time (3.4 vs. 15.0 h; P=0.001) and cost ($1,586 vs. $1,872; P=0.001).²⁰

Subsequently, Goldstein et al. conducted the multicenter CT-STAT trial, randomizing 699 low-risk patients with chest pain to early CCTA or rest-stress myocardial perfusion imaging (MPI), which includes positron emission tomography (PET) or single photon emission computed tomography (SPECT). CCTA significantly reduced the time to diagnosis (median 2.9 vs. 6.3 h; P<0.0001) and cost of care (median $2,137 vs. $3,458; P<0.0001). No significant differences were observed in major adverse cardiac events at 6 months among patients who underwent normal index testing (0.8% vs. 0.4%; P=0.29).²¹

The CT-COMPARE study is a single-center RCT of 562 low-risk patients with chest pain who had initial negative troponin test results and were randomized to undergo CCTA or exercise ECG (ExECG). CCTA demonstrated superior diagnostic performance (sensitivity 100% vs. 83%; specificity 94% vs. 91%; area under the curve 0.97 vs. 0.87) and resulted in shorter hospital stays (13.5 vs. 19.7 h; P<0.0005) and lower 30-day hospital costs ($2,193 vs. $2,704; P<0.001), despite higher downstream testing. No cardiovascular events occurred at the 30-day follow up.²²

Hoffmann et al. conducted a multicenter RCT involving 1,000 low-risk ED patients with suspected ACS, comparing early CCTA with standard evaluation. CCTA significantly reduced hospital length of stay (by 7.6 h; P<0.001) and increased direct discharge from the ED (47% vs. 12%; P<0.001), without increasing missed ACS or the risk of 28-day major adverse cardiac events. Despite more downstream testing and higher radiation exposure, cumulative costs were similar between the groups.²³

In the CATCH trial, 578 low-risk patients with chest pain (normal ECG, negative troponin) were randomized to undergo coronary CTA or standard functional testing. The CTA group experienced fewer primary events as a composite of cardiac death, myocardial infarction, hospitalization for unstable angina pectoris, late symptom-driven revascularizations, and readmission for chest pain (11% vs. 16%; hazard ratio [HR] 0.62; 95% CI 0.40, 0.98; P=0.04) and fewer major adverse cardiac events as cardiac death, myocardial infarction, hospitalization for unstable angina pectoris, and late symptom-driven revascularization (5 vs. 14; HR 0.36; 95% CI 0.16, 0.95).²⁴

In a single-center RCT of 411 hospitalized patients with chest pain, individuals were randomized to undergo CCTA (n=206) or stress testing (n=205). No differences were observed between the groups in terms of time to discharge, initiation of cardiac medications, downstream non-invasive testing (21% vs. 15%; P=0.10), or cardiovascular rehospitalizations (14% vs. 16%; P=0.50). However, invasive coronary angiography (11% vs. 2%; P=0.001) and percutaneous coronary intervention (6% vs. 0%; P<0.001) were more frequently performed in the CCTA group.²⁵

Piñeiro-Portela et al. conducted a randomized trial of 203 patients in a chest pain unit who had a low risk of ACS, comparing stress echocardiography (SE; n=103) with multidetector CT (MCT; n=100). They found no significant differences in the primary composite outcome (42% vs. 41%; P=0.91) or adverse events (5% vs. 7%; P=0.42). Although overall costs were similar, patients with a negative SE had lower costs than those with a negative MCT (€557 vs. €706; P<0.02).26

Risk of Bias

The risks of bias, namely the risks arising from the randomization process, deviations from the intended intervention, missing outcome data, measurement of outcomes, selection of reported results, and the overall risk, were assessed for each study (Figure 2). No domain was judged to be at high risk of bias in any of the included studies.

Figure 2.

Comparison of outcomes between coronary computed tomography angiography (CCTA) and standard care arms and the risk of bias. Forest plots show the risk ratio (RR), mean differences (MDs), or ratio of means (ROM) of each outcome for the CCTA vs. standard care arms. The size of central markers reflects the weight of each study. The risk of bias for each study and outcome was assessed using the Cochrane Risk of Bias 2 (RoB 2) tool. Currency conversion was performed using the following exchange rates: AU$1=US$0.96 and €1=US$1.30. CI, confidence interval; ED, emergency department; MI, myocardial infarction. SOC, standard care.

Outcomes

A forest plot of outcomes is presented in Figure 2, and an outline of findings, including the number of included studies, is summarized in the evidence profile shown in Table 2.

Table 2.

Evidence Profile

	No. studies	Study design	Certainty assessment					No. patients		Effect		Certainty	Importance
			Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	CCTA	SOC	Relative (95% CI)	Absolute (95% CI)
All-cause mortality	7	RCT	Not serious	Not serious	Not serious	Serious†	None	7/1,874	5/1,774	RR 1.36 (0.44, 4.21)	1 more per 1,000 (2 fewer to 9 more per 1,000)	Moderate	Critical
Non-fatal MI	7	RCT	Not serious	Not serious	Not serious	Not serious	None	13/1,874	22/1,774	RR 0.59 (0.23, 1.47)	5 fewer per 1,000 (10 fewer to 6 more per 1,000)	High	Critical
Length of stay	2	RCT	Not serious	Not serious	Not serious	Serious†	None	823	739	MD −6.23 h (−6.80, −5.66)	–	Moderate	Important
Revascularization	7	RCT	Not serious	Serious‡	Not serious	Not serious	None	132/1,874	77/1,774	RR 1.99 (1.13, 3.50)	43 more per 1,000 (6 to 109 more per 1,000)	Moderate	Important
Invasive coronary angiography	7	RCT	Not serious	Serious‡	Not serious	Not serious	None	216/1,874	151/1,774	RR 1.43 (1.04, 1.98)	37 more per 1,000 (3 to 83 more per 1,000)	Moderate	Important
Revisit to ED	6	RCT	Not serious	Not serious	Not serious	Not serious	None	101/1,668	99/1,569	RR 0.94 (0.72, 1.23)	4 fewer per 1,000 (18 fewer to 15 more per 1,000)	High	Important
Radiation exposure	3	RCT	Not serious	Serious‡	Not serious	Serious†	None	1,184	1,077	MD 3.94 mSv (−5.96, 13.83)	–	Low	Important
Healthcare costs	5	RCT	Not serious	Serious‡	Not serious	Not serious	None	1,383	1,278	ROM 0.82 (0.72, 0.94)	–	Moderate	Important

^†Due to either a limited number of RCTs or a small number of events, imprecision was judged to be serious. ^‡Inconsistency was downgraded due to substantial heterogeneity (I² >50%). MD, mean difference; N/A, not applicable; ROM, ratio of means; RR, relative risk; SOC, standard of care. Other abbreviations as in Table 1.

Among the critical outcomes, all-cause mortality and non-fatal myocardial infarction were reported in all 7 included studies, encompassing 3,648 patients. All-cause death occurred in 7 (0.4%) of 1,874 patients in the CCTA group and 5 (0.3%) of 1,774 patients in the standard care group (RR 1.36; 95% CI 0.44, 4.21). Furthermore, 13 (0.7%) of the 1,874 patients in the CCTA group and 22 (1.2%) of the 1,774 patients in the standard care group experienced non-fatal myocardial infarction, with no significant differences between the groups (RR 0.59; 95% CI 0.23, 1.47).

Among the important outcomes, length of hospital stay was evaluated in 2 studies including 1,562 patients, revascularization and invasive coronary angiography were analyzed in 7 studies with a total of 3,648 patients, ED revisits were assessed in 6 studies comprising 3,237 patients, radiation exposure was reported in 3 studies including 2,261 patients, and healthcare costs were analyzed in 5 studies with a total of 2,661 patients. Length of hospital stay was shorter in the CCTA group (MD −6.23 h; 95% CI −6.80, −5.66). In the present study, most patients were discharged directly from the ED. In a study by Hamilton-Craig et al.,²² 90% of patients were discharged from the ED, and in a study by Goldstein et al.,²⁰ 90% of patients in the CCTA group and 97% of those in the standard care group were discharged directly from the ED. According to Hoffmann et al.,²³ ED discharge rates were 47% in the CCTA group and 12% in the standard care group, with an additional 30% and 60% discharged from the observation unit and 21% and 25% discharged from hospital, respectively.²³ In a study by Piñeiro-Portela et al., approximately 70% of patients were discharged from the ED.²⁶ The number of patients who underwent revascularization was significantly higher in the CCTA group (132 of 1,874; 7.0%) compared with the standard care group (77 of 1,774; 4.3%; RR 1.99; 95% CI 1.13, 3.50). In addition, the number of patients who underwent invasive coronary angiography was also higher in the CCTA group (216 of 1,874; 11.5%) than in the standard care group (151 of 1,774; 8.5%; RR 1.43; 95% CI 1.04, 1.98). There was no significant difference in ED revisits between the groups, with 101 (6.1%) of 1,668 patients in the CCTA group and 99 (6.3%) of 1,569 patients in the standard care group (RR 0.94; 95% CI 0.72, 1.23). Although no significant difference in radiation exposure was observed between the 2 groups, the certainty of evidence was rated as low (MD 3.94; 95% CI −5.96, 13.83). Furthermore, healthcare costs were slightly lower in the CCTA group (ratio of means 0.82; 95% CI 0.72, 0.94).

Publication Bias and Quality of Evidence

Since visual inspection of the funnel plots revealed no apparent asymmetry (Supplementary Figure), the certainty of the evidence regarding publication bias for each outcome was rated as not serious according to the GRADE approach (Table 2). Based on the GRADE approach, the certainty of evidence for radiation exposure was rated as low due to concerns about inconsistency and the inclusion of only 2 RCTs. For all-cause mortality, length of hospital stay, revascularization, invasive coronary angiography, and healthcare costs, inconsistency was identified as a concern, either due to heterogeneity among the studies or the small number of events and/or included RCTs, resulting in a moderate certainty rating. In contrast, the certainty of evidence for non-fatal myocardial infarction, length of hospital stay, and revisit to the ED was rated as high (Table 2).

Discussion

This systematic review revealed that among low-risk patients with NSTE-ACS, early CCTA performed in the ED did not lead to reductions in all-cause mortality, non-fatal myocardial infarction, or ED revisit compared with standard care. Although the rate of revascularization and invasive coronary angiography were higher in the CCTA group, early CCTA was associated with a shorter length of hospital stay. Moreover, there was no significant difference in radiation exposure between the 2 groups, whereas healthcare costs were slightly lower in the CCTA group.

Clinical Benefits of CCTA in Low-Risk Patients Presenting With Suspected ACS

Patients with NSTE-ACS represent a heterogeneous population, and current guidelines recommend risk stratification to guide management.^6–8,27 For those at high risk, early invasive coronary angiography is strongly recommended.^6–8,28,29 In contrast, among low-risk patients, invasive coronary angiography has shown limited clinical benefit,^30,31 and non-invasive testing, such as CCTA or stress testing during hospitalization, is recommended.^6–8 In real-world clinical settings, low-risk patients are often discharged from the ED without hospitalization, and outpatient non-invasive testing is subsequently performed. However, previous studies have shown that a small proportion of patients with low-risk features may still have underlying ACS.^9,10 Therefore, early CCTA in the ED may be a valuable tool to safely identify such patients and support safe discharge decisions.

In this systematic review, we focused on a low-risk population characterized by the resolution of chest pain at presentation, absence of significant elevation in cardiac biomarkers such as troponin, and no apparent ischemic changes on electrocardiography. Based on 7 RCTs,^20–26 we compared early CCTA performed in the ED with standard care. There were no significant differences between the groups in terms of adverse clinical events, including all-cause mortality. However, hospital stay was shorter in the CCTA group. Radiation exposure did not differ significantly in the CCTA group, while healthcare costs were slightly lower compared with standard care. Although radiation exposure would generally be expected to be higher in the CCTA group, this finding may be related to the fact that only 2 studies were included in the analysis, one of which (the CT-STAT trial) was an RCT comparing CCTA with MPI, which also involves radiation exposure.²¹ This may have contributed to the absence of a statistically significant difference. Therefore, the certainty of evidence for radiation exposure was rated as low, and the results should be interpreted with caution. Nevertheless, recent advances in CCTA have led to a substantial reduction in radiation exposure compared with earlier techniques, and several studies have suggested that coronary CT may be performed with lower radiation doses than invasive coronary angiography.^32–34 Furthermore, both revascularization and invasive coronary angiography were performed more frequently in the CCTA group. Given that there was no corresponding increase in non-fatal myocardial infarction or all-cause mortality in the standard care group, it is possible that, in this low-risk population, incidentally detected stable plaques by CCTA were also included as targets for invasive angiography and revascularization. These results are in line with previous studies.^11–13,35

Barbosa et al. reported the utility of CCTA in patients presenting to the ED with acute chest pain.³⁵ In contrast to the present study, this analysis included a mixed population of low- to intermediate-risk patients rather than only low-risk individuals. Consistent with our findings, their study demonstrated that among low- to intermediate-risk patients, CCTA did not significantly differ from standard care in terms of all-cause mortality (RR 0.83; 95% CI 0.37, 1.88), cardiovascular mortality (RR 1.53; 95% CI 0.06, 37.40), or non-fatal myocardial infarction (RR 0.90; 95% CI 0.58, 1.38). However, length of hospital stay was significantly reduced in the CCTA group (RR 0.86; 95% CI 0.78, 0.95). Notably, the reduction in length of stay was more pronounced in the low- to intermediate-risk subgroup than in high-risk patients, suggesting that the benefit of CCTA in shortening hospital stay may be greater in populations including low-risk individuals. Additionally, the study reported significantly lower costs in the low- to intermediate-risk group (ratio of means 0.79; 95% CI 0.70, 0.90) and no significant difference in radiation exposure (MD 1.99; 95% CI −2.62, 6.59), which are findings that closely align with our results. As previously described, the patient population in the study by Barbosa et al. had a broader spectrum of risk, and specific findings limited to low-risk patients were not presented.³⁵ Therefore, our analysis, which focused on low-risk individuals, provides novel insights.

Chen et al. conducted a systematic review evaluating the utility of CCTA in patients with chest pain who were at low to intermediate risk.¹¹ Although the review included studies involving elective ischemia testing,³⁶ which differs from the acute presentation of patients included in our analysis, the findings are largely consistent with our results. Specifically, compared with a conventional strategy, CCTA did not increase the risk of all-cause mortality (RR 0.95; 95% CI 0.64, 1.40), major adverse cardiovascular events (RR 1.10; 95% CI 0.92, 1.30), or hospital readmission (RR 0.96; 95% CI 0.66, 1.40). However, the rate of invasive coronary angiography was significantly higher in the CCTA group (RR 1.44; 95% CI 1.28, 1.63).¹¹

Based on the current evidence, CCTA in low-risk patients presenting to the ED appears to have limited effectiveness in reducing adverse clinical outcomes, such as all-cause mortality and non-fatal MI. Although CCTA may lead to an increased use of revascularization and invasive coronary angiography, it can reduce ED length of stay and overall healthcare costs. No significant differences in radiation exposure were observed between the CCTA and standard care groups; however, the certainty of evidence was low, and the findings should be considered inconclusive.

In the population included in this systematic review, the incidence of adverse clinical events was very low, even in the standard care group. However, CCTA provided a basis for safely discharging patients without increasing the occurrence of such events, which may be considered a valuable clinical benefit. Given the high sensitivity and negative predictive value of CCTA,^37–39 these findings suggest that CCTA may facilitate the safe and early discharge of low-risk patients with NSTE-ACS.

Study Limitations

The present study had several limitations. First, although the 0/1-h algorithm using high-sensitivity troponin is now commonly used in the evaluation of NSTE-ACS,^6–8 some of the included studies may have used conventional troponin assays rather than high-sensitivity assays.^20,21,26 As a result, the background of standard care may differ from current clinical practice, highlighting the need for further RCTs. Second, in several of the included studies, the standard of care group routinely underwent MPI, which may explain the lack of significant differences in radiation exposure between the groups. Last, outcomes such as length of stay and radiation exposure were reported in only a limited number of studies. Therefore, these results should be interpreted with caution.

Conclusions

The use of CCTA in low-risk patients with NSTE-ACS in the ED did not increase the risk of all-cause death, non-fatal myocardial infarction, or revisits to the ED. CCTA may not be associated with a significant increase in radiation exposure; however, the certainty of evidence is low, and the findings should be considered inconclusive. Although CCTA use likely results in a higher rate of revascularization and invasive coronary angiography, early CCTA was probably associated with a shorter length of hospital stay and a slight reduction in healthcare costs in our study. These findings suggest that performing CCTA may be a useful strategy for facilitating the safe and early discharge of low-risk patients with NSTE-ACS from the ED.

Disclosures

T. Matoba is a member of Circulation Reports’ Editorial Team. T. Matoba reports research grants from Amgen. T. Mano received research grants from Abbott Medical Japan. T. Kondo received lecture fees from Abbott Japan LLC, AstraZeneca K.K., Boehringer Ingelheim, Ono Pharmaceutical Co., Ltd, Kowa Company, Ltd, Kyowa Kirin Co., Ltd, and Novartis Pharma K.K. The other authors declare no conflicts of interest with regard to this article.

IRB Information

Not applicable.

Supplementary Files

Supplementary File 1

Supplementary Table. Supplementary Figure.

Funding Statement

Sources of Funding: This work was supported by the Japan Resuscitation Council, Japan Circulation Society, MHLW grant no. 24FA1017, and the Intramural Research Fund for Cardiovascular Disease of the National Cerebral and Cardiovascular Center (23-B-7).

Data Availability

The deidentified participant data will be shared on a request basis. Please directly contact the corresponding author to request data sharing.