Outcomes After Coronary Computed Tomography Angiography in the Emergency Department

ACR Appropriateness Criteria® Acute Nonspecific Chest Pain-Low Probability of Coronary Artery Disease

Patients with acute nonspecific chest pain and low probability for coronary disease remain an important clinical management dilemma. We focus on evidence for imaging, in an integrated decision-making setting. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Impact of Education-based HEART Score Pathway on Coronary Computed Tomography Angiography Utilization and Yield in the Emergency Department

OBJECTIVE

There is a growing consensus to reduce unnecessary testing among low-risk chest pain patients. The objective of this study was to evaluate the impact of implementing an education-based HEART score pathway in the emergency department on coronary computed tomography angiography (CCTA) utilization and yield.

METHODS

A retrospective before and after intervention study was conducted at a single site. Adult emergency department patients undergoing CCTA for suspected acute coronary syndrome were included. Primary outcomes were CCTA utilization and yield. Utilization was defined as the percentage of patients evaluated with CCTA and yield was calculated as the percentage of patients with a diagnosis of obstructive coronary artery disease, defined as ≥50% stenosis in any one coronary artery due to atherosclerosis.

RESULTS

1540 patients undergoing CCTAs were included. CCTA utilization before and after were 2.2% [95% confidence interval (CI) 2.0-2.3] and 2.0% (95% CI 1.9-2.2), respectively; mean difference 0.1% (95% CI -0.1 to 0.3; P = 0.21). The mean age was 53 years (SD = 11) and females were 52%. Of 1477 patients included in CCTA yield analysis, patients diagnosed with obstructive coronary artery disease before and after were 15.0% (95% CI 12.6-17.7) and 16.2% (95% CI 13.6-19.1), respectively; mean difference 1.2% (95% CI -2.6 to 5.1; P = 0.53).

CONCLUSIONS

There was no significant change in the CCTA utilization or yield after the implementation of an education-based HEART pathway in a large academic center. Our findings suggest adopting a more comprehensive approach for deploying such evidence-based protocols to increase institutional compliance.

Comparison Between Anatomical and Functional Imaging Modalities for Evaluation of Chest Pain in the Emergency Department

Evaluation of chest pain in the emergency department (ED) frequently employs a noninvasive strategy, including coronary computed tomography angiography (CCTA), stress echocardiography (SE), or myocardial perfusion imaging (MPI). We sought to report the real-world experience of utilizing CCTA compared with SE and MPI at an urban hospital ED. We conducted a retrospective cohort study of consecutively enrolled patients presenting with chest pain who had normal or nondiagnostic electrocardiogram (ECG), negative initial troponin-T, at least intermediate risk based on modified Diamond-Forrester criteria, and who underwent CCTA, SE, or MPI based on their individual test eligibility criteria. The primary outcome was ED discharge time. Secondary outcomes included test utilization and 30-days rehospitalization rates. The 2,143 patients who were included (mean age was 56 ± 12 years; 55% women) utilization rate (test performed/eligible) was lower for CCTA (n = 354/1,329) and MPI (n = 530/1,435) compared with SE (n = 1,259/1,650), p <0.001. Mean ED discharge times for both CCTA and SE were 12.5 ± 7.4 versus 16 ± 7.3 hours for MPI (p <0.0001). Patients with SE and CCTA were less likely to undergo coronary angiography (29%, 25%, vs 52% for MPI). There was a 1% cardiac-related 30-days rehospitalization rate in the CCTA group versus 1% in SE and 3% in the MPI group (p <0.01). In conclusion, CCTA and SE were associated with faster ED discharge and lower frequency of diagnostic coronary angiography. Notwithstanding its clinical utility, CCTA was underutilized at our large urban ED setting.

SPECT Versus PET Myocardial Perfusion Imaging in Patients with Equivocal CT

PURPOSE OF REVIEW

The most pertinent clinical question in post-coronary computed tomography angiography (CCTA) patients is the assessment of the physiological significance of an anatomically identified stenosis. The clinical application of radionuclide MPI using single-photon emission computed tomography (SPECT) versus positron emission tomography (PET) in the evaluation and management of patients with an inconclusive CCTA is reviewed using a case-based approach.

RECENT FINDINGS

Recent evidence suggests that CCTA is the most sensitive non-invasive test to exclude angiographic CAD and may be an effective first-line test especially among symptomatic low-intermediate risk patients. However, in the presence of angiographic atherosclerosis, its specificity and positive predictive value for identifying flow-limiting stenosis are modest. Radionuclide myocardial perfusion imaging offers accurate quantitative assessment of myocardial ischemia, which helps with risk stratification and patient management especially the potential need for revascularization. Routine accurate quantifications of myocardial blood flow and flow reserve are major advantages of PET MPI, which are especially useful when used in patients at intermediate-high clinical risk.

Is Physiologic Stress Test with Imaging Comparable to Anatomic Examination of Coronary Arteries by Coronary Computed Tomography Angiography to Investigate Coronary Artery Disease? - A Systematic Review and Meta-Analysis

Objective Coronary computed tomography angiography (CCTA) is a noninvasive diagnostic modality that remains underutilized compared to functional stress testing (ST) for investigating coronary artery disease (CAD). Several patients are misdiagnosed with noncardiac chest pain (CP) that eventually die from a cardiovascular event in subsequent years. We compared CCTA to ST to investigate CP. Methods We searched MEDLINE, PubMed, Cochrane Library, and Embase from January 1, 2007 to July 1, 2018 for randomized controlled trials (RCTs) comparing CCTA to ST in patients who presented with acute or stable CP. We used Review Manager (RevMan) [Computer program] Version 5.3 (Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014) for review and analysis. Results We included 16 RCTs enrolling 21,210 patients; there were more patients with hyperlipidemia and older patients in the ST arm compared to the CCTA arm. There was no difference in mortality: 103 in the CCTA arm vs. 110 in the ST arm (risk ratio [RR] = 0.93, 95% confidence interval [CI] = 0.71-1.21, P = .58, and I² = 0%). A significant reduction was seen in myocardial infarctions (MIs) after CCTA compared to ST: 115 vs. 156 (RR = 0.71, CI = 0.56-0.91, P < .006, I²=0%). On subgroup analysis, the CCTA arm had fewer MIs vs. the ST with imaging subgroup (RR = 0.70, CI = 0.54-0.89, P = .004, I² = 0%) and stable CP subgroup (RR = 0.66, CI = 0.50-0.88, P = .004, I² = 0%). The CCTA arm showed significantly higher invasive coronary angiograms and revascularizations and significantly reduced follow-up testing and recurrent hospital visits. A trend towards increased unstable anginas was seen in the CCTA arm. Conclusions Our analysis showed a significant reduction in downstream MIs, hospital visits, and follow-up testing when CCTA is used to investigate CAD with no difference in mortality.

Diagnosis and risk stratification of chest pain patients in the emergency department: focus on acute coronary syndromes. A position paper of the Acute Cardiovascular Care Association

This paper provides an update on the European Society of Cardiology task force report on the management of chest pain. Its main purpose is to provide an update on the decision algorithms and diagnostic pathways to be used in the emergency department for the assessment and triage of patients with chest pain symptoms suggestive of acute coronary syndromes.

Long-term health outcomes and cost-effectiveness of coronary CT angiography in patients with suspicion for acute coronary syndrome

BACKGROUND

Randomized trials have shown favorable clinical outcomes for coronary CT angiography (CTA) in patients with suspected acute coronary syndrome (ACS). Our goal was to estimate the cost-effectiveness of coronary CTA as compared to alternative management strategies for ACP patients over lifetime.

METHODS

Markov microsimulation model was developed to compare cost-effectiveness of competitive strategies for ACP patients: 1) coronary CTA, 2) standard of care (SOC), 3) AHA/ACC Guidelines, and 4) expedited emergency department (ED) discharge protocol with outpatient testing. ROMICAT-II trial was used to populate the model with low to intermediate risk of ACS patient data, whereas diagnostic test-, treatment effect-, morbidity/mortality-, quality of life- and cost data were obtained from the literature. We predicted test utilization, costs, 1-, 3-, 10-year and over lifetime cardiovascular morbidity/mortality for each strategy. We determined quality adjusted life years (QALY) and incremental cost-effectiveness ratio. Observed outcomes in ROMICAT-II were used to validate the short-term model.

RESULTS

Estimated short-term outcomes accurately reflected observed outcomes in ROMICAT-II as coronary CTA was associated with higher costs ($4,490 vs. $2,513-$4,144) and revascularization rates (5.2% vs. 2.6%-3.7%) compared to alternative strategies. Over lifetime, coronary CTA dominated SOC and ACC/AHA Guidelines and was cost-effective compared to expedited ED protocol ($49,428/QALY). This was driven by lower cardiovascular mortality (coronary CTA vs. expedited discharge: 3-year: 1.04% vs. 1.10-1.17; 10-year: 5.06% vs. 5.21-5.36%; respectively).

CONCLUSION

Coronary CTA in patients with suspected ACS renders affordable long-term health benefits as compared to alternative strategies.

Use of Initial Noninvasive Cardiac Testing and Association with Downstream Healthcare Resource: A Retrospective Review of Resources Used Across a 12-Month Window for Probable Type I Myocardial Infarction Patients

BACKGROUND

Clinical guidelines provide clinicians with substantial discretion in the use of noninvasive cardiac testing for patients with suspected coronary artery disease. Repeat testing, frequent emergency department (ED) visits, and increases in other cardiac-related procedures can be a burden on patients and payers and can complicate treatment planning. We assessed downstream healthcare resource utilization (HCRU) for patients undergoing initial single-photon emission computed tomography (SPECT), myocardial perfusion imaging (MPI), stress echocardiography (ECHO), or exercise treadmill testing (ETT) with probable type I myocardial infarction (MI).

METHODS

Electronic medical records data from 12,130 patients with probable type I MI presenting to EDs within a large healthcare system comprised of 11 adult hospitals were retrospectively analyzed. Logistic and linear regression determined the individual contribution of SPECT-MPI, ETT, and ECHO on repeat cardiovascular (CV) testing, inpatient visits, outpatient visits, and cardiac-related costs within 12 months of the index visit.

RESULTS

The majority of patients received SPECT-MPI for the index-testing event (56.5%), followed by ETT (29.2%) and ECHO (14.3%). Patients who had SPECT-MPI at the index visit were less likely to have a repeat CV testing visit (odds ratio [OR] 0.77, 95% confidence interval [CI] 0.62‒0.96; p = 0.020) or an inpatient visit (OR 0.70, 95% CI 0.49‒0.98; p = 0.039) than those who underwent ETT or ECHO. ETT and ECHO were not predictive of any outcome.

CONCLUSIONS

SPECT-MPI does not result in more downstream HCRU than ETT or ECHO and is associated with a lower likelihood of repeat non-invasive CV testing and inpatient visits.

Clinical Use of CT-Derived Fractional Flow Reserve in the Emergency Department

OBJECTIVES

This study sought to examine the feasibility, safety, clinical outcomes, and costs associated with computed tomography-derived fractional flow reserve (FFR_CT) in acute chest pain (ACP) patients in a coronary computed tomography angiography (CTA)-based triage program.

BACKGROUND

FFR_CT is useful in determining lesion-specific ischemia in patients with stable ischemic heart disease, but its utility in ACP has not been studied.

METHODS

ACP patients with no known coronary artery disease undergoing coronary CTA and coronary CTA with FFR_CT were studied. FFR_CT ≤0.80 was considered positive for hemodynamically significant stenosis.

RESULTS

Among 555 patients, 297 underwent coronary CTA and FFR_CT (196 negative, 101 positive), whereas 258 had coronary CTA only. The rejection rate for FFR_CT was 1.6%. At 90 days, there was no difference in major adverse cardiac events (including death, nonfatal myocardial infarction, and unexpected revascularization after the index visit) between the coronary CTA and FFR_CT groups (4.3% vs. 2.7%; p = 0.310). Diagnostic failure, defined as discordance between the coronary CTA or FFR_CT results with invasive findings, did not differ between the groups (1.9% vs. 1.68%; p = NS). No deaths or myocardial infarction occurred with negative FFR_CT when revascularization was deferred. Negative FFR_CT was associated with higher nonobstructive disease on invasive coronary angiography (56.5%) than positive FFR_CT (8.0%) and coronary CTA (22.9%) (p < 0.001). There was no difference in overall costs between the coronary CTA and FFR_CT groups ($8,582 vs. $8,048; p = 0.550).

CONCLUSIONS

In ACP, FFR_CT is feasible, with no difference in major adverse cardiac events and costs compared with coronary CTA alone. Deferral of revascularization is safe with negative FFR_CT, which is associated with higher nonobstructive disease on invasive angiography.

Quantification of plaque characteristics detected by dual source computed tomography angiography to predict myocardial ischemia as assessed by single photon emission computed tomography myocardial perfusion imaging

Background

We aim to evaluate the relationship between quantitative plaque characteristics detected by dual-source computed tomography angiography (DSCTA) and myocardial ischemia as assessed by single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI).

Methods

In this study, 460 consecutive patients with suspected coronary artery disease (CAD) underwent DSCTA and stress/rest SPECT-MPI, and 179 patients with coronary artery plaques were quantitatively analyzed. Quantitative coronary artery plaque measurements including total plaque volume, the volume of non-calcified plaque, calcified plaque volume, low-density noncalcified plaque volume, total plaque burden, calcified plaque burden, non-calcified plaque burden, low-density non-calcified plaque (LDNCP) burden, remodeling index, plaque length, maximum diameter stenosis were provided by the automated software (Release 5.6.5, Circle Cardiovascular Imaging, Canada). Univariate and multivariate logistic regression analysis was performed to assess the correlation between quantitative plaque characteristics and myocardial ischemia to determine if plaque characteristics were independent of clinical risk factors and significant CAD.

Results

One hundred and seventy-nine patients (65% males) with suspected-CAD, undergoing DSCTA and stress/rest SPECT-MPI and single vessel ischemia were considered. There were significant correlations between quantitative assessment of plaque features and myocardial ischemia with details as follow: total plaque volume [25.2 (17.8-37.8) vs. 15.6 (10.3-24.9) mm³, P<0.001], calcified plaque volume (1.6±7.1 vs. 2.3±6.4 mm³, P=0.019), non-calcified plaque volume [23.6 (16.6-35.9) vs. 14.6 (10.3-22.8) mm³, P<0.001)], LDNCP volume [4.9 (2.1-8.2) vs. 2.2 (1.0-5.5) mm³, P=0.003], total plaque burden (47.6%±17.1% vs. 36.2%±17.3%, P=0.002), calcified plaque burden (1.5%±5.5% vs. 2.9%±6.9%, P=0.014), non-calcified plaque burden (46.1%±18.8% vs. 33.3%±16.4%, P=0.001), LDNCP burden [12.3% (6.4-17.7) vs. 3.3% (1.6-5.3), P<0.001], remodeling index [1.2 (1.1-1.4) vs. 1.0 (1.1-1.2), P<0.001], plaque length [4.0 (3.2-6.1) vs. 3.3 (2.8-3.8) mm, P=0.009], maximum diameter stenosis [18.1% (10.0-52.9) vs. 12.9% (6.5-18.5), P=0.011]. In a multivariate analysis, low-density noncalcified plaque burden (OR 1.33; 95% CI, 1.16-1.53, P<0.001) remained a significant predictor of myocardial ischemia after adjusting for stenosis ≥50% and gender. The area under curve (AUC) of the model containing LDNCP burden, stenosis ≥50% and gender was 0.875 (95% CI, 0.812-0.938), which was significantly better than the model with stenosis ≥50% and gender (AUC 0.729; 95% CI, 0.633-0.825).

Conclusions

Quantitative plaque characteristics detected by DSCTA are independently correlated with the incidence of myocardial ischemia by SPECT-MPI in patients with suspected CAD.

Effects of obesity on noninvasive test results in patients with suspected cardiac ischemia: Insights from the PROMISE trial

BACKGROUND

Obesity is a risk factor for coronary artery disease (CAD), but adiposity may mimic symptoms of CAD and reduce the accuracy of diagnostic testing.

METHODS

Patients from the PROMISE trial (n = 8889) were classified according to body mass index (BMI). We assessed relationships between BMI, physician's preference of functional test, test positivity, and results of invasive coronary angiography (Cath) using logistic regression models.

RESULTS

Nearly half (48%) of the patients had BMI ≥ 30 kg/m², and 20% had BMI ≥ 35. Providers were more likely to prefer nuclear myocardial perfusion imaging (MPI) over other functional tests as BMI increased. The rate of test positivity with coronary computed tomographic angiography (CTA) was not different (10% vs. 12%) in patients with BMI ≥35 vs. < 35. The same was true for stress echocardiogram and stress electrocardiogram (positivity 8-13%, P > 0.8 for both). In contrast, MPI was significantly more likely to be positive in those with BMI ≥35 vs. <35 (18% vs. 13%; P = 0.001). The likelihood of obstructive CAD at Cath did not differ with BMI ≥35 vs. <35 in patients having CTA (52% vs. 59%, P = 0.22), but among MPI patients, Cath positivity was only 29% with BMI ≥35 vs. 48% with BMI <35 (P = 0.005). Radiation exposure increased with higher BMI in both MPI and CTA groups.

CONCLUSIONS

Increasing levels of obesity adversely affect the diagnostic yield of MPI more than CTA. The degree of obesity should be considered when choosing evaluation strategies for patients with chest pain.

CLINICAL TRIAL REGISTRATION

PROMISE ClinicalTrials.gov number, NCT01174550.

Coronary Computed Tomography Angiography Improving Outcomes in Patients with Chest Pain

Purpose of Review

To provide an overview of recent studies of coronary computed tomography angiography (CCTA) and how it has helped to improve clinical outcomes for patients presenting with chest pain.

Recent Findings

Randomised controlled trials have uniformly demonstrated that the use of CCTA is associated with improvements in patient diagnosis, management and treatments as well as the avoidance of unnecessary invasive coronary angiography. These changes have been associated with consistent reductions in long-term rates of fatal or non-fatal myocardial infarction.

Summary

Major beneficial effects in clinical management and patient outcomes are seen with the use of coronary computed tomography angiography. CCTA might be considered to be the first test of choice for the investigation of coronary heart disease.

Risk stratification and role for additional diagnostic testing in patients with acute chest pain and normal high-sensitivity cardiac troponin levels

Background

Normal high sensitivity cardiac troponin (hs-cTn) assays rule out acute myocardial infarction (AMI) with great accuracy, but additional non-invasive testing is frequently ordered. This observational study evaluates whether clinical characteristics can contribute to risk stratification and could guide referral for additional testing.

Methods

918 serial patients with acute chest pain and normal hs-cTnT levels were prospectively included. Major adverse cardiac events (MACE) and non-invasive test results were assessed during one-year follow-up. Patients were classified as low and high risk based on clinical characteristics.

Results

MACE occurred in 6.1% of patients and mainly comprised revascularizations (86%). A recent abnormal stress test, suspicious history, a positive family history and higher baseline hs-cTnT levels were independent predictors of MACE with odds ratios of 16.00 (95%CI:6.25–40.96), 16.43 (6.36–42.45), 2.33 (1.22–4.42) and 1.10 (1.01–1.21), respectively. Absence of both recent abnormal stress test and suspicious history identified 86% of patients. These patients were at very low risk for MACE (0.4% in 30-days and 2.3% in one-year). Despite this, the majority (287/345 = 83%) of additional tests were performed in low risk patients, with <10% abnormal test findings. The diagnostic yield was significantly higher in the remaining higher risk patients, 40% abnormal test findings and a positive predictive value of 70% for MACE. Similar results were observed in patients without known coronary artery disease.

Conclusions

Clinical characteristics can be used to identify low risk patients with acute chest pain and normal hs-cTnT levels. Current strategies in the emergency department result in numerous additional tests, which are mostly ordered in patients at very low risk and have a low diagnostic yield.

2018 Guidelines of the Taiwan Society of Cardiology, Taiwan Society of Emergency Medicine and Taiwan Society of Cardiovascular Interventions for the management of non ST-segment elevation acute coronary syndrome

In Taiwan, the incidence of non-ST segment elevation acute coronary syndrome (NSTE-ACS) continues to increase in recent years. The purpose of this guideline is to help health care professionals in Taiwan to use adequate tests and treatments for management of NSTE-ACS. For rapid diagnosis, in addition to history and physical examination, 0/3 h rapid diagnosis protocol with high sensitivity cardiac troponin assay is recommended in this guideline. Dual antiplatelet and anticoagulation therapies are important parts in the initial treatment. Risk stratification should be performed to identify high risk patients for early coronary angiography. Through evaluation of the coronary anatomy and other clinical factors, the decision for coronary revascularization, either by percutaneous coronary intervention or coronary artery bypass grafting, should be decided by the heart team. The duration of dual antiplatelet therapy should be given for at least 12 months after discharge. Other secondary preventive medications are also recommended for long term use.

Evaluation of right ventricular function by coronary computed tomography angiography using a novel automated 3D right ventricle volume segmentation approach: a validation study

OBJECTIVES

To evaluate right ventricle (RV) function by coronary computed tomography angiography (CTA) using a novel automated three-dimensional (3D) RV volume segmentation tool in comparison with clinical reference modalities.

METHODS

Twenty-six patients with severe end-stage heart failure [left ventricle (LV) ejection fraction (EF) <35%] referred to CTA were enrolled. A specific individually tailored biphasic contrast agent injection protocol was designed (80%/20% high/low flow) was designed. Measurement of RV function [EF, end-diastolic volume (EDV), end-systolic volume (ESV)] by CTA was compared with tricuspid annular plane systolic excursion (TAPSE) by transthoracic echocardiography (TTE) and right heart invasive catheterisation (IC).

RESULTS

Automated 3D RV volume segmentation was successful in 26 (100%) patients. Read-out time was 3 min 33 s (range, 1 min 50s-4 min 33s). RV EF by CTA was stronger correlated with right atrial pressure (RAP) by IC (r = -0.595; p = 0.006) but weaker with TAPSE (r = 0.366, p = 0.94). When comparing TAPSE with RAP by IC (r = -0.317, p = 0.231), a weak-to-moderate non-significant inverse correlation was found. Interobserver correlation was high with r = 0.96 (p < 0.001), r = 0.86 (p < 0.001) and r = 0.72 (p = 0.001) for RV EDV, ESV and EF, respectively. CT attenuation of the right atrium (RA) and right ventricle (RV) was 196.9 ± 75.3 and 217.5 ± 76.1 HU, respectively.

CONCLUSIONS

Measurement of RV function by CTA using a novel 3D volumetric segmentation tool is fast and reliable by applying a dedicated biphasic injection protocol. The RV EF from CTA is a closer surrogate of RAP than TAPSE by TTE.

KEY POINTS

• Evaluation of RV function by cardiac CTA by using a novel 3D volume segmentation tool is fast and reliable. • A biphasic contrast agent injection protocol ensures homogenous RV contrast attenuation. • Cardiac CT is a valuable alternative modality to CMR for the evaluation of RV function.

Cardiac CT in the Emergency Department: Contrasting Evidence from Registries and Randomized Controlled Trials

PURPOSE OF REVIEW

To compare outcomes between registries and randomized controlled trials of coronary computed tomographic angiography (CCTA)-based versus standard of care approaches to the initial evaluation of patients with acute chest pain.

RECENT FINDINGS

Randomized trials have demonstrated CCTA to be a safe and efficient tool for triage of low- to intermediate-risk patients presenting to the emergency department with chest pain. Recent studies demonstrate heterogeneous result using different standard of care approaches for evaluation of hard endpoints in comparison with standard evaluation. Also, there has been continued concern for increase in subsequent testing after coronary CTA. Although CCTA improves detection of coronary artery disease, it is uncertain if it will bring improvement of long-term health outcomes at this point of time. Careful analysis of the previous results and further investigation will be required to validate evaluation of hard endpoints.

Coronary CT Angiography: Use in Patients With Chest Pain Presenting to Emergency Departments

OBJECTIVE

Previously published reports have shown that coronary CT angiography (CCTA) is a more efficient method of diagnosis than myocardial perfusion imaging (MPI) and stress echocardiography for patients presenting to emergency departments (EDs) with acute chest pain. In light of this evidence, the objective of this study was to examine recent trends in the use of these techniques in EDs.

MATERIALS AND METHODS

The nationwide Medicare Part B databases for 2006-2015 were the data source. The Current Procedural Terminology, version 4, codes for CCTA, MPI, and stress echocardiography were selected. Medicare place-of-service codes were used to determine procedure volumes in EDs. Medicare specialty codes were used to ascertain how many of these examinations were interpreted by radiologists, cardiologists, and other physicians as a group.

RESULTS

From 2006 to 2015, there was essentially no change in the number of MPI examinations performed in EDs for patients using Medicare (22,342 in 2006, 22,338 in 2015) or in the number of stress echocardiograms (3544 in 2006, 3520 in 2015). By contrast, the number of CCTA examinations increased rapidly, from 126 in 2006 to 1919 in 2015 (compound annual growth rate, 35%). Despite this rapid growth, patients in EDs underwent 11.6 times as many MPI as CCTA examinations in 2015. In that last year of the study, radiologists interpreted 78% of ED MPI and 83% of ED CCTA examinations.

CONCLUSION

Use of CCTA in EDs has increased rapidly, but far more MPI examinations are still being performed. This finding suggests that recently acquired evidence is not yet being fully acted upon.

Immediate Stress Echocardiography for Low-Risk Chest Pain Patients in the Emergency Department: A Prospective Observational Cohort Study

BACKGROUND

Evaluation and disposition of low-risk chest pain (CP) patients in the emergency department (ED) is time consuming and expensive. Low-risk CP often results in hospital admission to rule out myocardial infarction, which leads to additional costs and delays.

OBJECTIVE

Our aim was to assess whether an immediate exercise stress echocardiogram (IESE) in the ED will allow safe, efficient, and cost-effective evaluation and discharge of patients with low-risk CP.

METHODS

Low-risk CP patients (TIMI [Thrombolysis in Myocardial Infarction] score 0-1) presenting to the ED with normal electrocardiogram, no history of coronary artery disease, and negative troponin T received IESE. We followed these patients for major adverse cardiac events and compared them to a control cohort of similar-risk patients admitted with traditional care at 1 and 6 months.

RESULTS

We enrolled 216 patients, 117 IESE and 109 control. We obtained follow-up at 1 and 6 months in 94% of the IESE group and 88% in the control group. There was no difference in diagnostic catheterization or percutaneous coronary intervention between the 2 groups (6.0% and 1.7% vs. 6.4% and 1.8%; p = 0.89). Median time from triage to discharge was significantly shorter with IESE (572.6 min vs. 1466.0 min), resulting in significantly lower cost ($4380.50 vs. $6191.70). There were no adverse events related to IESE or early discharge.

CONCLUSIONS

In our study, IESE for low-risk CP patients presenting to the ED has the potential to be equally safe, more expeditious, and more cost effective than admission to an observation unit.

Defining Quality in Cardiovascular Imaging: A Scientific Statement From the American Heart Association

The aims of the current statement are to refine the definition of quality in cardiovascular imaging and to propose novel methodological approaches to inform the demonstration of quality in imaging in future clinical trials and registries. We propose defining quality in cardiovascular imaging using an analytical framework put forth by the Institute of Medicine whereby quality was defined as testing being safe, effective, patient-centered, timely, equitable, and efficient. The implications of each of these components of quality health care are as essential for cardiovascular imaging as they are for other areas within health care. Our proposed statement may serve as the foundation for integrating these quality indicators into establishing designations of quality laboratory practices and developing standards for value-based payment reform for imaging services. We also include recommendations for future clinical research to fulfill quality aims within cardiovascular imaging, including clinical hypotheses of improving patient outcomes, the importance of health status as an end point, and deferred testing options. Future research should evolve to define novel methods optimized for the role of cardiovascular imaging for detecting disease and guiding treatment and to demonstrate the role of cardiovascular imaging in facilitating healthcare quality.

Chest pain triage: Current trends in the emergency departments in the United States

Chest pain is one of the most common complaints in the emergency department (ED). Over the past decade, there has been a significant shift in the approach to patients with chest pain in the ED. With the development of improved cardiac biomarkers, the validation of clinical scoring systems, and an increasing emphasis on shared patient medical decision making, increasing numbers of patients in the ED are being evaluated without requiring admission to the hospital.

Computed Tomography Angiographic Assessment of Acute Chest Pain

Acute chest pain is a leading cause of Emergency Department visits. Computed tomography angiography plays a vital diagnostic role in such cases, but there are several common challenges associated with the imaging of acute chest pain, which, if unrecognized, can lead to an inconclusive or incorrect diagnosis. These imaging challenges fall broadly into 3 categories: (1) image acquisition, (2) image interpretation (including physiological and pathologic mimics), and (3) result communication. The aims of this review are to describe and illustrate the most common challenges in the imaging of acute chest pain and to provide solutions that will facilitate accurate diagnosis of the causes of acute chest pain in the emergency setting.

Coronary Computed Tomography Angiography vs Functional Stress Testing for Patients With Suspected Coronary Artery Disease: A Systematic Review and Meta-analysis

Importance

Coronary computed tomography angiography (CCTA) is a new approach for the diagnosis of anatomical coronary artery disease (CAD), but it is unclear how CCTA performs compared with the standard approach of functional stress testing.

Objective

To compare the clinical effectiveness of CCTA with that of functional stress testing for patients with suspected CAD.

Data Sources

A systematic literature search was conducted in PubMed and MEDLINE for English-language randomized clinical trials of CCTA published from January 1, 2000, to July 10, 2016.

Study Selection

Researchers selected randomized clinical trials that compared a primary strategy of CCTA with that of functional stress testing for patients with suspected CAD and reported data on patient clinical events and changes in therapy.

Data Extraction and Synthesis

Two reviewers independently extracted data from and assessed the quality of the trials. This analysis followed the PRISMA statement for reporting systematic reviews and meta-analyses and used the Cochrane Collaboration's tool for assessing risk of bias in randomized trials. The Mantel-Haenszel method was used to conduct the primary analysis. Summary relative risks were calculated with a random-effects model.

Main Outcomes and Measures

The outcomes of interest were all-cause mortality, cardiac hospitalization, myocardial infarction, invasive coronary angiography, coronary revascularization, new CAD diagnoses, and change in prescription for aspirin and statins.

Results

Thirteen trials were included, with 10 315 patients in the CCTA arm and 9777 patients in the functional stress testing arm who were followed up for a mean duration of 18 months. There were no statistically significant differences between CCTA and functional stress testing in death (1.0% vs 1.1%; risk ratio [RR], 0.93; 95% CI, 0.71-1.21) or cardiac hospitalization (2.7% vs 2.7%; RR, 0.98; 95% CI, 0.79-1.21), but CCTA was associated with a reduction in the incidence of myocardial infarction (0.7% vs 1.1%; RR, 0.71; 95% CI, 0.53-0.96). Patients undergoing CCTA were significantly more likely to undergo invasive coronary angiography (11.7% vs 9.1%; RR, 1.33; 95% CI, 1.12-1.59) and revascularization (7.2% vs 4.5%; RR, 1.86; 95% CI, 1.43-2.43). They were also more likely to receive a diagnosis of new CAD and to have initiated aspirin or statin therapy.

Conclusions and Relevance

Compared with functional stress testing, CCTA is associated with a reduced incidence of myocardial infarction but an increased incidence of invasive coronary angiography, revascularization, CAD diagnoses, and new prescriptions for aspirin and statins. Despite these differences, CCTA is not associated with a reduction in mortality or cardiac hospitalizations.

Improved Assessment of Chest pain Trial (IMPACT): assessing patients with possible acute coronary syndromes

OBJECTIVE

To examine the safety and efficacy of the Improved Assessment of Chest pain Trial (IMPACT) protocol, a strategy for accelerated assessment of patients presenting to emergency departments (EDs) with chest pain.

DESIGN, SETTING AND PARTICIPANTS

IMPACT was an intervention trial at a single tertiary referral hospital (Royal Brisbane and Women's Hospital) during February 2011 - March 2014. 1366 prospectively recruited patients presenting to the ED with symptoms of suspected acute coronary syndrome (ACS) were stratified into groups at low, intermediate or high risk of an ACS.

INTERVENTION

High risk patients were treated according to NHFA/CSANZ guidelines. Low and intermediate risk patients underwent troponin testing (sensitive assay) 0 and 2 hours after presentation. Intermediate risk patients underwent objective testing after the second troponin test; low risk patients were discharged without further objective testing.

MAIN OUTCOME MEASURES

The primary outcome was an ACS within 30 days of presentation. Secondary outcomes were ED and hospital lengths of stay (LOS).

RESULTS

The IMPACT protocol stratified 244 (17.9%) patients to low risk, 789 (57.7%) to intermediate risk, and 333 (24.4%) to high risk categories. The overall 30-day ACS rate was 6.6%, but there were no ACS events in the low risk group, and 14 (1.8%) in the intermediate risk group. The median hospital LOS was 5.1 hours (IQR, 4.2-5.6 h) for low risk and 7.7 hours (IQR, 6.1-21 h) for intermediate risk patients.

CONCLUSIONS

The IMPACT protocol safely and efficiently allowed a large proportion of patients presenting to EDs with chest pain to undergo accelerated assessment for risk of an ACS.

CLINICAL TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12611000206921.

Age- and sex-based resource utilisation and costs in patients with acute chest pain undergoing cardiac CT angiography: pooled evidence from ROMICAT II and ACRIN-PA trials

OBJECTIVES

To determine resource utilisation according to age and gender-specific subgroups in two large randomized diagnostic trials.

METHODS

We pooled patient-specific data from ACRIN-PA 4005 and ROMICAT II that enrolled subjects with acute chest pain at 14 US sites. Subjects were randomized between a standard work-up and a pathway utilizing cardiac computed tomography angiography (CCTA) and followed for the occurrence of acute coronary syndrome (ACS) and resource utilisation during index hospitalisation and 1-month follow-up. Study endpoints included diagnostic accuracy of CCTA for the detection of ACS as well as resource utilisation.

RESULTS

Among 1240 patients who underwent CCTA, negative predictive value of CCTA to rule out ACS remained very high (≥99.4%). The proportion of patients undergoing additional diagnostic testing and cost increased with age for both sexes (p < 0.001), and was higher in men as compared to women older than 60 years (43.1% vs. 23.4% and $4559 ± 3382 vs. $3179 ± 2562, p < 0.01; respectively). Cost to rule out ACS was higher in men (p < 0.001) and significantly higher for patients older than 60 years ($2860-5935 in men, p < 0.001).

CONCLUSIONS

CCTA strategy in patients with acute chest pain results in varying resource utilisation according to age and gender-specific subgroups, mandating improved selection for advanced imaging.

KEY POINTS

• In this analysis, CAD and ACS increased with age and male gender. • CCTA in patients with acute chest pain results in varying resource utilisation. • Significant increase of diagnostic testing and cost with age for both sexes. • Cost to rule out ACS is higher in men and patients >60 years. • Improved selection of subjects for cardiac CTA result in more resource-driven implementation.

Acute chest pain evaluation using coronary computed tomography angiography compared with standard of care: a meta-analysis of randomised clinical trials

Objective

Coronary CT angiography (CCTA) has certain advantages compared with stress testing including greater accuracy in identifying obstructive coronary disease. The aim of the study was to perform a systematical review and meta-analysis comparing CCTA with other standard-of-care (SOC) approaches in evaluation of patients with acute chest pain.

Methods

Electronic databases were systematically searched to identify randomised clinical trials of patients with acute chest pain comparing CCTA with SOC approaches. We examined the following end points: mortality, major adverse cardiac events (MACE), myocardial infarction (MI), invasive coronary angiography (ICA) and revascularisation. Pooled risk ratios (RR) and their 95% CIs were calculated using random-effects models.

Results

Ten trials with 6285 patients were included. The trials used different definitions and implementation for SOC but all used physiologic testing. The clinical follow-up ranged from 1 to 19 months. There were no significant differences in all-cause mortality (RR 0.48, 95% CI 0.17 to 1.36, p=0.17), MI (RR 0.82, 95% CI 0.49 to 1.39, p=0.47) or MACE (RR 0.98, 95% CI 0.67 to 1.43, p=0.92) between the groups. However, significantly higher rates of ICA (RR 1.32, 95% CI 1.07 to 1.63, p=0.01) and revascularisation (RR 1.77, 95% CI 1.35 to 2.31, p<0.0001) were observed in the CCTA arm.

Conclusions

Compared with other SOC approaches use of CCTA is associated with similar major adverse cardiac events but higher rates of revascularisation in patients with acute chest pain.

Comparative effectiveness of coronary CT angiography vs stress cardiac imaging in patients following hospital admission for chest pain work-up: The Prospective First Evaluation in Chest Pain (PERFECT) Trial

BACKGROUND

Because the frequency of cardiac event rates is low among chest pain patients following either performance of coronary CT angiography (CCTA) or stress testing, there is a need to better assess how these tests influence the central management decisions that follow from cardiac testing. The present study was performed to assess the relative impact of CCTA vs stress testing on medical therapies and downstream resource utilization among patients admitted for the work-up of chest pain.

METHODS

The admitted patients were randomized in a 1:1 ratio to either cardiac imaging stress test or CCTA. Primary outcomes were time to discharge, change in medication usage, and frequency of downstream testing, cardiac interventions, and cardiovascular re-hospitalizations. We randomized 411 patients, 205 to stress testing, and 206 to CCTA.

RESULTS

There were no differences in time to discharge or initiation of new cardiac medications at discharge. At 1 year follow-up, there was no difference in the number of patients who underwent cardiovascular downstream tests in the CCTA vs stress test patients (21% vs 15%, P = .1) or cardiovascular hospitalizations (14% vs 16%, P = .5). However, there was a higher frequency of invasive angiography in the CCTA group (11% vs 2%, P = .001) and percutaneous coronary interventions (6% vs 0%, P < .001).

CONCLUSIONS

Randomization of hospitalized patients admitted for chest pain work-up to either CCTA or to stress testing resulted in similar discharge times, change in medical therapies at discharge, frequency of downstream noninvasive testing, and repeat hospitalizations. However, a higher frequency of invasive coronary angiography and revascularization procedures were performed in the CCTA arm. (ClinicalTrials.gov number, NCT01604655.).

Coronary CT angiography in acute chest pain

Coronary computed tomographic angiography has become a reliable diagnostic tool in the evaluation of patients with chest pain. Studies have shown this modality to be accurate and safe when compared with conventional methods of assessing patients with chest pain. We review the recent developments with coronary computed tomographic angiography and devote particular attention toward its application to triage patients in the emergency department.

Computed Tomography and Cardiac Magnetic Resonance in Ischemic Heart Disease

Ischemic heart disease is a complex disease process caused by the development of coronary atherosclerosis, with downstream effects on the left ventricular myocardium. It is characterized by a long preclinical phase, abrupt development of myocardial infarction, and more chronic disease states such as stable angina and ischemic cardiomyopathy. Recent advances in computed tomography (CT) and cardiac magnetic resonance (CMR) now allow detailed imaging of each of these different phases of the disease, potentially allowing ischemic heart disease to be tracked during a patient’s lifetime. In particular, CT has emerged as the noninvasive modality of choice for imaging the coronary arteries, whereas CMR offers detailed assessments of myocardial perfusion, viability, and function. The clinical utility of these techniques is increasingly being supported by robust randomized controlled trial data, although the widespread adoption of cardiac CT and CMR will require further evidence of clinical efficacy and cost effectiveness.

Cardiac Computed Tomography Assessment in Acute Coronary Syndromes — Do We Have Time for It in Emergency Settings?

The diagnosis and treatment of acute coronary syndrome remain a challenge for clinicians in many clinical settings, especially in patients with previous low-to-intermediate risk. Due to its high specificity and sensitivity for detecting significant coronary artery stenoses, cardiac computed tomography angiography (CCTA) tends to be used more frequently in the emergency room (ER) in the last years. This technique has been associated with a higher rate of safe discharge in patients with chest pain, less time spent in the ER, and decreased costs related to further investigations. In cases positive for coronary artery stenosis, CCTA can accurately evaluate the indication for percutaneous coronary angioplasty and can offer relevant information related to the characteristics of the coronary plaques, being able to detect vulnerable coronary plaques. The aim of this manuscript is to highlight the possibility of using CCTA in the ER in the assessment of patients with chest pain and to show the benefits of the procedure regarding safety, costs, accuracy, and time.

Clinical risk factors alone are inadequate for predicting significant coronary artery disease

OBJECTIVE

We sought to derive and validate a model for identifying suspected ACS patients harboring undiagnosed significant coronary artery disease (CAD).

METHODS

This was a secondary analysis of data from a randomized control trial (RCT). Patients randomized to the CTA arm of an RCT examining a CTA-based strategy for ruling-out acute coronary syndrome (ACS) constitute the derivation cohort, which was randomly divided into a training dataset (2/3, used for model derivation) and a test dataset (1/3, used for internal validation (IV)). ED patients from a different center receiving CTA to evaluate for suspected ACS constitute the external validation (EV) cohort. Primary outcome was CTA-assessed significant CAD (stenosis of ≥50% in a major coronary artery).

RESULTS

In the derivation cohort, 11.2% (76/679) of subjects had CTA-assessed significant CAD, and in the EV cohort, 8.2% of subjects (87/1056) had CTA-assessed significant CAD. Age was the strongest predictor of significant CAD among the clinical risk factors examined. Predictor variables included in the derived logistic regression model were: age, sex, tobacco use, diabetes, and race. This model exhibited an area under the receiver operating characteristic curve (ROC AUC) of 0.72 (95% CI: 0.61-0.83) based on IV, and 0.76 (95% CI: 0.70, 0.82) based on EV. The derived random forest model based on clinical risk factors yielded improved but not sufficient discrimination of significant CAD (ROC AUC = 0.76 [95% CI: 0.67-0.85] based on IV). Coronary artery calcium score was a more accurate predictor of significant CAD than any combination of clinical risk factors (ROC AUC = 0.85 [95% CI: 0.76-0.94] based on IV; ROC AUC = 0.92 [95% CI: 0.88-0.95] based on EV).

CONCLUSIONS

Clinical risk factors, either individually or in combination, are insufficient for accurately identifying suspected ACS patients harboring undiagnosed significant coronary artery disease.

Cardiac Imaging in the Diagnosis of Coronary Artery Disease

Coronary artery disease (CAD) continues to be a leading cause of morbidity and mortality worldwide. Although invasive coronary angiography has previously been the gold standard in establishing the diagnosis of CAD, there is a growing shift to more appropriately use the cardiac catheterization laboratory to perform interventional procedures once a diagnosis of CAD has been established by noninvasive imaging modalities rather than using it primarily as a diagnostic facility to confirm or refute CAD. With ongoing technological advancements, noninvasive imaging plays a pre-eminent role in not only diagnosing CAD but also informing the choice of appropriate therapies, establishing prognosis, all while containing costs and providing value-based care. Multiple imaging modalities are available to evaluate patients suspected of having coronary ischemia, such as stress electrocardiography, stress echocardiography, single-photon emission computed tomography myocardial perfusion imaging, positron emission tomography, coronary computed tomography (CT) angiography, and magnetic resonance imaging. These imaging modalities can variably provide functional and anatomical delineation of coronary stenoses and help guide appropriate therapy. This review will discuss their advantages and limitations and their usage in the diagnostic pathway for patients with CAD. We also discuss newer technologies such as CT fractional flow reserve, CT angiography with perfusion, whole-heart coronary magnetic resonance angiography with perfusion, which can provide both anatomical as well as functional information in the same test, thus obviating the need for multiple diagnostic tests to obtain a comprehensive assessment of both, plaque burden and downstream ischemia. Recognizing that clinicians have a multitude of tests to choose from, we provide an underpinning of the principles of ischemia detection by these various modalities, focusing on anatomy vs physiology, the database justifying their use, their prognostic capabilities and lastly, their appropriate and judicious use in this era of patient-centered, cost-effective imaging.

Functional compared to anatomical imaging in the initial evaluation of patients with suspected coronary artery disease: An international, multi-center, randomized controlled trial (IAEA-SPECT/CTA study)

OBJECTIVE

To test the hypothesis that, in the initial evaluation of patients with suspected coronary artery disease (CAD), stress myocardial perfusion imaging (MPI) would result in less downstream testing than coronary computed tomographic angiography (CCTA).

METHODS

In this international, randomized trial, mildly symptomatic patients with an intermediate likelihood of having CAD, and asymptomatic patients at intermediate risk of cardiac events, underwent either initial stress-rest MPI or CCTA. The primary outcome was downstream noninvasive or invasive testing at 6 months. Secondary outcomes included cumulative effective radiation dose (ERD) and costs at 12 months.

RESULTS

We recruited 303 patients (151 MPI and 152 CTA) from 6 centers in 6 countries. The initial MPI was abnormal in 29% (41/143) and CCTA in 56% (79/141) of patients. Fewer patients undergoing initial stress-rest MPI had further downstream testing at 6 months (adjusted OR 0.51, 95% CI 0.28-0.91, P = 0.023). There was a small increase in the median cumulative ERD with MPI (9.6 vs. 8.8 mSv, P = 0.04), but no difference in costs between the two strategies at 12 months.

CONCLUSION

In the management of patients with suspected CAD, a strategy of initial stress MPI is substantially less likely to require further downstream testing than initial testing with CCTA.

TRIAL REGISTRATION

clinicaltrials.gov identification number NCT01368770.

Estimating Effective Dose of Radiation From Pediatric Cardiac CT Angiography Using a 64-MDCT Scanner: New Conversion Factors Relating Dose-Length Product to Effective Dose

OBJECTIVE

The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children.

MATERIALS AND METHODS

Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials. Organ doses were used to calculate the ED on the basis of weighting factors published in 1991 in International Commission on Radiological Protection (ICRP) publication 60 and in 2007 in ICRP publication 103. The EDs and the scanner-reported dose-length products were used to determine conversion factors for each scan mode. The effect of infant heart rate on the ED and the conversion factors was also assessed.

RESULTS

The mean conversion factors calculated using the current definition of ED that appeared in ICRP publication 103 were as follows: 0.099 mSv · mGy-1 · cm-1, for the 1-year-old phantom, and 0.049 mSv · mGy-1 · cm-1, for the 10-year-old phantom. These conversion factors were a mean of 37% higher than the corresponding conversion factors calculated using the older definition of ED that appeared in ICRP publication 60. Varying the heart rate did not influence the ED or the conversion factors.

CONCLUSION

Conversion factors determined using the definition of ED in ICRP publication 103 and cardiac, rather than chest, scan coverage suggest that the radiation doses that children receive from cardiac CT performed using a contemporary 64-MDCT scanner are higher than the radiation doses previously reported when older chest conversion factors were used. Additional up-to-date pediatric cardiac CT conversion factors are required for use with other contemporary CT scanners and patients of different age ranges.

The RAPID-CTCA trial (Rapid Assessment of Potential Ischaemic Heart Disease with CTCA) - a multicentre parallel-group randomised trial to compare early computerised tomography coronary angiography versus standard care in patients presenting with suspected or confirmed acute coronary syndrome: study protocol for a randomised controlled trial

BACKGROUND

Emergency department attendances with chest pain requiring assessment for acute coronary syndrome (ACS) are a major global health issue. Standard assessment includes history, examination, electrocardiogram (ECG) and serial troponin testing. Computerised tomography coronary angiography (CTCA) enables additional anatomical assessment of patients for coronary artery disease (CAD) but has only been studied in very low-risk patients. This trial aims to investigate the effect of early CTCA upon interventions, event rates and health care costs in patients with suspected/confirmed ACS who are at intermediate risk.

METHODS/DESIGN

Participants will be recruited in about 35 tertiary and district general hospitals in the UK. Patients ≥18 years old with symptoms with suspected/confirmed ACS with at least one of the following will be included: (1) ECG abnormalities, e.g. ST-segment depression >0.5 mm; (2) history of ischaemic heart disease; (3) troponin elevation above the 99th centile of the normal reference range or increase in high-sensitivity troponin meeting European Society of Cardiology criteria for 'rule-in' of myocardial infarction (MI). The early use of ≥64-slice CTCA as part of routine assessment will be compared to standard care. The primary endpoint will be 1-year all-cause death or recurrent type 1 or type 4b MI at 1 year, measured as the time to such event. A number of secondary clinical, process and safety endpoints will be collected and analysed. Cost effectiveness will be estimated in terms of the lifetime incremental cost per quality-adjusted life year gained. We plan to recruit 2424 (2500 with ~3% drop-out) evaluable patients (1212 per arm) to have 90% power to detect a 20% versus 15% difference in 1-year death or recurrent type 1 MI or type 4b MI, two-sided p < 0.05. Analysis will be on an intention-to-treat basis. The relationship between intervention and the primary outcome will be analysed using Cox proportional hazard regression adjusted for study site (used to stratify the randomisation), age, baseline Global Registry of Acute Coronary Events score, previous CAD and baseline troponin level. The results will be expressed as a hazard ratio with the corresponding 95% confidence intervals and p value.

DISCUSSION

The Rapid Assessment of Potential Ischaemic Heart Disease with CTCA (RAPID-CTCA) trial will recruit 2500 participants across about 35 hospital sites. It will be the first study to investigate the role of CTCA in the early assessment of patients with suspected or confirmed ACS who are at intermediate risk and including patients who have raised troponin measurements during initial assessment.

TRIAL REGISTRATION

ISRCTN19102565 . Registered on 3 October 2014. ClinicalTrials.gov: NCT02284191.