Coronary computed tomographic angiography for rapid discharge of low-risk patients with potential acute coronary syndromes

Virtual (Computed) Fractional Flow Reserve: Future Role in Acute Coronary Syndromes

The current management of acute coronary syndromes (ACS) is with an invasive strategy to guide treatment. However, identifying the lesions which are physiologically significant can be challenging. Non-invasive imaging is generally not appropriate or timely in the acute setting, so the decision is generally based upon visual assessment of the angiogram, supplemented in a small minority by invasive pressure wire studies using fractional flow reserve (FFR) or related indices. Whilst pressure wire usage is slowly increasing, it is not feasible in many vessels, patients and situations. Limited evidence for the use of FFR in non-ST elevation (NSTE) ACS suggests a 25% change in management, compared with traditional assessment, with a shift from more to less extensive revascularisation. Virtual (computed) FFR (vFFR), which uses a 3D model of the coronary arteries constructed from the invasive angiogram, and application of the physical laws of fluid flow, has the potential to be used more widely in this situation. It is less invasive, fast and can be integrated into catheter laboratory software. For severe lesions, or mild disease, it is probably not required, but it could improve the management of moderate disease in 'real time' for patients with non-ST elevation acute coronary syndromes (NSTE-ACS), and in bystander disease in ST elevation myocardial infarction. Its practicability and impact in the acute setting need to be tested, but the underpinning science and potential benefits for rapid and streamlined decision-making are enticing.

High-Risk Chief Complaints I: Chest Pain-The Big Three (an Update)

Nontraumatic chest pain is a frequent concern of emergency department patients, with causes that range from benign to immediately life threatening. Identifying those patients who require immediate/urgent intervention remains challenging and is a high-risk area for emergency medicine physicians where incorrect or delayed diagnosis may lead to significant morbidity and mortality. This article focuses on the 3 most prevalent diagnoses associated with adverse outcomes in patients presenting with nontraumatic chest pain, acute coronary syndrome, thoracic aortic dissection, and pulmonary embolism. Important aspects of clinical evaluation, diagnostic testing, treatment, and disposition and other less common causes of lethal chest pain are also discussed.

CCTA in patients with positive troponin and low clinical suspicion for ACS: a useful diagnostic option to exclude obstructive CAD

PURPOSE

It is uncertain whether patients with elevated troponin and non-classical presentation of acute coronary syndrome (ACS) should receive coronary CT angiography (CCTA). A proportion of these patients will have no coronary artery disease (CAD) and would benefit from non-invasive investigations and expedited discharge. Objectives were to determine most common diagnoses and rate of ACS among patients with positive troponin and low clinical suspicion of ACS who received CCTA.

METHODS

IRB approved retrospective analysis of 491 consecutive patients in a level I trauma center ED referred for CCTA between April 4, 2015 to April 2, 2017. Patients were included if there was an elevated troponin (TnI > 0.045 μg/L) and atypical chest pain within 24 h prior to imaging. One hundred one patients met inclusion criteria; 17 excluded due to technical factors or history. Scans performed on dual-source CT.

RESULTS

Eighty-four patients (47 men, 37 women) with median TnI of 0.11 ± 0.21 μg/L underwent CCTA 8.20 ± 6.41 h after first elevated Tn. Mean age was 53.2 ± 14.6 years. CCTA demonstrated absence of CAD in 39 patients (46.4%; 20 M, 19 F). CAD < 25% stenosis was observed in 24 (28.6%; 9 M, 15 F). CAD with 25-50% stenosis was observed in seven (8.3%; six M, one F). CAD > 50% stenosis was observed in 11 (13.1%; 9 M, 2 F), and non-diagnostic in three (3.6%, 3 M, 0 F). Forty-six (56.8%) were discharged directly from ED with median stay 15.82 ± 6.41 h.

CONCLUSIONS

Use of CCTA in ED patients with elevated troponin and low clinical suspicion for ACS allowed obstructive CAD to be excluded in 83%.

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.

SEALONE (Safety and Efficacy of Coronary Computed Tomography Angiography with Low Dose in Patients Visiting Emergency Room) trial: study protocol for a randomized controlled trial

Objective

Chest pain is one of the most common complaints in the emergency department (ED). Cardiac computed tomography angiography (CCTA) is a frequently used tool for the early triage of patients with low- to intermediate-risk acute chest pain. We present a study protocol for a multicenter prospective randomized controlled clinical trial testing the hypothesis that a low-dose CCTA protocol using prospective electrocardiogram (ECG)-triggering and limited-scan range can provide sufficient diagnostic safety for early triage of patients with acute chest pain.

Methods

The trial will include 681 younger adult (aged 20 to 55) patients visiting EDs of three academic hospitals for acute chest pain or equivalent symptoms who require further evaluation to rule out acute coronary syndrome. Participants will be randomly allocated to either low-dose or conventional CCTA protocol at a 2:1 ratio. The low-dose group will undergo CCTA with prospective ECG-triggering and restricted scan range from sub-carina to heart base. The conventional protocol group will undergo CCTA with retrospective ECG-gating covering the entire chest. Patient disposition is determined based on computed tomography findings and clinical progression and all patients are followed for a month. The primary objective is to prove that the chance of experiencing any hard event within 30 days after a negative low-dose CCTA is less than 1%. The secondary objectives are comparisons of the amount of radiation exposure, ED length of stay and overall cost.

Results and Conclusion

Our low-dose protocol is readily applicable to current multi-detector computed tomography devices. If this study proves its safety and efficacy, dose-reduction without purchasing of expensive newer devices would be possible.

Comparison of mid- to long-term clinical outcomes between anatomical testing and usual care in patients with suspected coronary artery disease: A meta-analysis of randomized trials

BACKGROUND

Controversies remain regarding clinical outcomes following initial strategies of coronary computed tomography angiography (CCTA) vs usual care with functional testing in patients with suspected coronary artery disease (CAD).

HYPOTHESIS

CCTA as initial diagnostic strategy results in better mid- to long-term outcomes than usual care in patients with suspected CAD.

METHODS

We searched PubMed, Embase, and Cochrane Library for randomized controlled trials comparing clinical outcomes during ≥6 months' follow-up between initial anatomical testing by CCTA vs usual care with functional testing in patients with suspected CAD. Occurrence of all-cause mortality, nonfatal myocardial infarction (MI), and major adverse cardiovascular events (MACE), and use of invasive coronary angiography and coronary revascularization, were compared between the 2 diagnostic strategies.

RESULTS

Twelve trials were included (20 014 patients; mean follow-up, 20.5 months). Patients undergoing CCTA as initial noninvasive testing had lower risk of nonfatal MI compared with those treated with usual care (risk ratio [RR]: 0.70, 95% confidence interval [CI]: 0.52-0.94, P = 0.02). There was a tendency for reduced MACE following initial CCTA strategy, but not for risk of all-cause mortality. Compared with functional testing, the CCTA strategy increased use of invasive coronary angiography (RR: 1.53, 95% CI: 1.12-2.09, P = 0.007) and coronary revascularization (RR: 1.49, 95% CI: 1.11-2.00, P = 0.007).

CONCLUSIONS

Anatomical testing with CCTA as the initial noninvasive diagnostic modality in patients with suspected CAD resulted in lower risk of nonfatal MI than usual care with functional testing, at the expense of more frequent use of invasive procedures.

A systematic review of imaging anatomy in predicting functional significance of coronary stenoses determined by fractional flow reserve

Fractional flow reserve (FFR) is the current gold standard to assess the physiological significance of coronary stenoses. With the development of coronary imaging techniques, several anatomic parameters have been investigated in vivo and their associations with FFR have been studied. The aim of this review is to summarize the accuracy of anatomic parameters derived by the present coronary imaging techniques including invasive coronary angiography, coronary computed tomography angiography, intravascular ultrasound and optical coherence tomography, in predicting a significant FFR. The impact of patient characteristics, lesion locations, variability of FFR and imaging resolution on the predictive ability are discussed.

Highly sensitive troponin and coronary computed tomography angiography in the evaluation of suspected acute coronary syndrome in the emergency department

The evaluation of patients presenting to the emergency department with suspected acute coronary syndrome (ACS) remains a clinical challenge. The traditional assessment includes clinical risk assessment based on cardiovascular risk factors with serial electrocardiograms and cardiac troponin measurements, often followed by advanced cardiac testing as inpatient or outpatient (i.e. stress testing, imaging). Despite this costly and lengthy work-up, there is a non-negligible rate of missed ACS with an increased risk of death. There is a clinical need for diagnostic strategies that will lead to rapid and reliable triage of patients with suspected ACS. We provide an overview of the evidence for the role of highly sensitive troponin (hsTn) in the rapid and efficient evaluation of suspected ACS. Results of recent research studies have led to the introduction of hsTn with rapid rule-in and rule-out protocols into the guidelines. Highly sensitive troponin increases the sensitivity for the detection of myocardial infarction and decreases time to diagnosis; however, it may decrease the specificity, especially when used as a dichotomous variable, rather than continuous variable as recommended by guidelines; this may increase clinician uncertainty. We summarize the evidence for the use of coronary computed tomography angiography (CTA) as the rapid diagnostic tool in this population when used with conventional troponin assays. Coronary CTA significantly decreases time to diagnosis and discharge in patients with suspected ACS, while being safe. However, it may lead to increase in invasive procedures and includes radiation exposure. Finally, we outline the opportunities for the combined use of hsTn and coronary CTA that may result in increased efficiency, decreased need for imaging, lower cost, and decreased radiation dose.

Efficiency and safety of coronary CT angiography compared to standard care in the evaluation of patients with acute chest pain: a Canadian study

The optimal assessment of patients with chest pain and possible acute coronary syndrome (ACS) remains a diagnostic dilemma for emergency physicians. Cardiac computed tomographic angiography (CCTA) may identify patients who can be safely discharged home from the emergency department (ED). The objective of the study was to compare the efficiency and safety of CCTA to standard care in patients presenting to the ED with low- to intermediate-risk chest pain. This was a single-center before-after study enrolling ED patients with chest pain and low to intermediate risk of ACS, before and after implementing a cardiac CT-based management protocol. The primary outcome was efficiency (time to diagnosis). Secondary outcomes included safety (30-day incidence of major adverse cardiovascular events (MACE)) and length of stay in the ED. We enrolled 258 patients: 130 in the standard care group and 128 in the cardiac CT-based management group. The cardiac CT group had a shorter time to diagnosis of 7.1 h (IQR 5.8-14.0) compared to 532.9 h (IQR 312.8-960.5) for the standard care group (p < 0.0001) but had a longer length of stay in the ED of 7.9 h (IQR 6.5-10.8) versus 5.5 h (IQR 3.9-7.7) (p < 0.0001). The MACE rate was 1.6 % in the standard care group and 0 % in the cardiac CT group. In conclusion, a cardiac CT-based management strategy to rule out ACS in ED patients with low- to intermediate-risk chest pain was safe and led to a shorter time to diagnosis but increased length of stay in the ED.

Noninvasive cardiac imaging in suspected acute coronary syndrome

Noninvasive cardiac imaging has an important role in the assessment of patients with acute-onset chest pain. In patients with suspected acute coronary syndrome (ACS), cardiac imaging offers incremental value over routine clinical assessment, the electrocardiogram, and blood biomarkers of myocardial injury, to confirm or refute the diagnosis of coronary artery disease and to assess future cardiovascular risk. This Review covers the current guidelines and clinical use of the common noninvasive imaging techniques, including echocardiography and stress echocardiography, computed tomography coronary angiography, myocardial perfusion scintigraphy, positron emission tomography, and cardiovascular magnetic resonance imaging, in patients with suspected ACS, and provides an update on the developments in noninvasive imaging techniques in the past 5 years.

Chest pain: coronary CT in the ER

Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years.

Cardiac CT angiography for evaluation of acute chest pain

Chest pain is the second most common emergency department (ED) presentation in the United States. Cardiac computed tomography angiography (CCTA) now plays an important role in the evaluation of patients with suspected acute coronary syndrome in the ED setting. In this article, we review the available techniques focused on the use of CCTA to evaluate patients fosr coronary atherosclerosis for timely triage of acute chest pain.

Safety and efficiency of outpatient versus emergency department-based coronary CT angiography for evaluation of patients with potential ischemic chest pain

BACKGROUND

While coronary CT angiography (coronary CTA) may be comparable to standard care in diagnosing acute coronary syndrome (ACS) in emergency department (ED) chest pain patients, it has traditionally been obtained prior to ED discharge and a strategy of delayed outpatient coronary CTA following an ED visit has not been evaluated.

OBJECTIVE

To investigate the safety of discharging stable ED patients and obtaining outpatient CCTA.

METHODS

At two urban Canadian EDs, patients up to 65 years with chest pain but no findings indicating presence of ACS were further evaluated depending upon time of presentation: (1) ED-based coronary CTA during normal working hours, (2) or outpatient coronary CTA within 72 hours at other times. All data were collected prospectively. The primary outcome was the proportion of patients who had an outpatient coronary CTA ordered and had a predefined major adverse cardiac event (MACE) between ED discharge and outpatient CT; secondary outcome was the ED length of stay in both groups.

RESULTS

From July 1, 2012 to June 30, 2014, we enrolled 521 consecutive patients: 350 with outpatient CT and 171 with ED-based CT. Demographics and risk factors were similar in both cohorts. No outpatient CT patients had a MACE prior to coronary CTA. (0.0%, 95% CI 0 to 0.9%) The median length of stay for ED-based evaluation was 6.6 hours (interquartile range 5.4 to 8.3 hours) while the outpatient group had a median length of stay of 7.0 hours (IQR 6.0 to 9.8 hours, n.s.).

CONCLUSIONS

In ED chest pain patients with a low risk of ACS, performing coronary CTA as an outpatient may be a safe strategy.

Cardiac computed tomography for the evaluation of the acute chest pain syndrome: state of the art

Coronary computed tomography angiography (CCTA) is recommended for the triage of acute chest pain in patients with a low-to-intermediate likelihood for acute coronary syndrome. Absence of coronary artery disease (CAD) confirmed by CCTA allows rapid emergency department discharge. This article shows that CCTA-based triage is as safe as traditional triage, reduces the hospital length of stay, and may provide cost-effective or even cost-saving care.

Korean guidelines for the appropriate use of cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Cardiac CT: atherosclerosis to acute coronary syndrome

Coronary computed tomographic angiography (CCTA) is a robust non-invasive method to assess coronary artery disease (CAD). Qualitative and quantitative assessment of atherosclerotic coronary stenosis with CCTA has been favourably compared with invasive coronary angiography (ICA) and intravascular ultrasound (IVUS). Importantly, it allows the study of preclinical stages of atherosclerotic disease, may help improve risk stratification and monitor the progressive course of the disease. The diagnostic accuracy of CCTA in the assessment of coronary artery bypass grafts (CABG) is excellent and the constantly improving technology is making the evaluation of stents feasible. Novel techniques are being developed to assess the functional significance of coronary stenosis. The excellent negative predictive value of CCTA in ruling out disease enables early and safe discharge of patients with suspected acute coronary syndromes (ACS) in the Emergency Department (ED). In addition, CCTA is useful in predicting clinical outcomes based on the extent of coronary atherosclerosis and also based on individual plaque characteristics such as low attenuation plaque (LAP), positive remodelling and spotty calcification. In this article, we review the role of CCTA in the detection of coronary atherosclerosis in native vessels, stented vessels, calcified arteries and grafts; the assessment of plaque progression, evaluation of chest pain in the ED, assessment of functional significance of stenosis and the prognostic significance of CCTA.

Discrepancy between clinician and research assistant in TIMI score calculation (TRIAGED CPU)

Introduction

Several studies have attempted to demonstrate that the Thrombolysis in Myocardial Infarction (TIMI) risk score has the ability to risk stratify emergency department (ED) patients with potential acute coronary syndromes (ACS). Most of the studies we reviewed relied on trained research investigators to determine TIMI risk scores rather than ED providers functioning in their normal work capacity. We assessed whether TIMI risk scores obtained by ED providers in the setting of a busy ED differed from those obtained by trained research investigators.

Methods

This was an ED-based prospective observational cohort study comparing TIMI scores obtained by 49 ED providers admitting patients to an ED chest pain unit (CPU) to scores generated by a team of trained research investigators. We examined provider type, patient gender, and TIMI elements for their effects on TIMI risk score discrepancy.

Results

Of the 501 adult patients enrolled in the study, 29.3% of TIMI risk scores determined by ED providers and trained research investigators were generated using identical TIMI risk score variables. In our low-risk population the majority of TIMI risk score differences were small; however, 12% of TIMI risk scores differed by two or more points.

Conclusion

TIMI risk scores determined by ED providers in the setting of a busy ED frequently differ from scores generated by trained research investigators who complete them while not under the same pressure of an ED provider.

Accuracy of multidetector computed tomography for detection of coronary artery stenosis in acute coronary syndrome compared with stable coronary disease: a CORE64 multicenter trial substudy

BACKGROUND

Multi-detector computed tomography angiography (MDCTA) is a promising method for risk assessment of patients with acute chest pain. However, its diagnostic performance in higher-risk patients has not been investigated in a large international multicenter trial. Therefore, in the present study we sought to estimate the diagnostic accuracy of MDCTA to detect significant coronary stenosis in patients with acute coronary syndrome (ACS).

METHODS

Patients included in the CORE64 study were categorized as suspected-ACS or non-ACS based on clinical data. A 64-row coronary MDCTA was performed before invasive coronary angiography (ICA) and both exams were evaluated by blinded, independent core laboratories.

RESULTS

From 371 patients included, 94 were categorized as suspected ACS and 277 as non-ACS. Patient-based analysis showed an area under the receiver-operating-characteristic curve (AUC) for detecting ≥ 50% coronary stenosis of 0.95 (95% CI: 0.88-0.98) in ACS and 0.92 (95% CI: 0.88-0.95) in non-ACS group (P=0.29). The sensitivity, specificity, positive and negative predictive values of MDCTA were 0.90(0.80-0.96), 0.88(0.70-0.98), 0.95(0.87-0.99) and 0.77(0.58-0.90) in suspected ACS patients and 0.87(0.81-0.92), 0.86(0.79-0.92), 0.91(0.85-0.95) and 0.82(0.74-0.89) in non-ACS patients (P NS for all comparisons). The mean calcium scores (CS) were 282 ± 449 in suspected ACS and 435 ± 668 in non-ACS group. The accuracy of CS to detect significant coronary stenosis was only moderate and the absence or minimal coronary artery calcification could not exclude the presence of significant coronary stenosis, particularly in ACS patients.

CONCLUSIONS

The diagnostic accuracy of MDCTA to detect significant coronary stenosis is high and comparable for both ACS and non-ACS patients.

Point-of-care assessment of platelet reactivity in the emergency department may facilitate rapid rule-out of acute coronary syndromes: a prospective cohort pilot feasibility study

OBJECTIVE

Accurate, efficient and cost-effective disposition of patients presenting to emergency departments (EDs) with symptoms suggestive of acute coronary syndromes (ACS) is a growing priority. Platelet activation is an early feature in the pathogenesis of ACS; thus, we sought to obtain an insight into whether point-of-care testing of platelet function: (1) may assist in the rule-out of ACS; (2) may provide additional predictive value in identifying patients with non-cardiac symptoms versus ACS-positive patients and (3) is logistically feasible in the ED.

DESIGN

Prospective cohort feasibility study.

SETTING

Two urban tertiary care sites, one located in the USA and the second in Argentina.

PARTICIPANTS

509 adult patients presenting with symptoms of ACS.

MAIN OUTCOME MEASURES

Platelet reactivity was quantified using the Platelet Function Analyzer-100, with closure time (seconds required for blood, aspirated under high shear, to occlude a 150 µm aperture) serving as the primary endpoint. Closure times were categorised as 'normal' or 'prolonged', defined objectively as the 90th centile of the distribution for all participants enrolled in the study. Diagnosis of ACS was made using the standard criteria. The use of antiplatelet agents was not an exclusion criterion.

RESULTS

Closure times for the study population ranged from 47 to 300 s, with a 90th centile value of 138 s. The proportion of patients with closure times ≥138 s was significantly higher in patients with non-cardiac symptoms (41/330; 12.4%) versus the ACS-positive cohort (2/105 (1.9%); p=0.0006). The specificity of 'prolonged' closure times (≥138 s) for a diagnosis of non-cardiac symptoms was 98.1%, with a positive predictive value of 95.4%. Multivariate analysis revealed that the closure time provided incremental, independent predictive value in the rule-out of ACS.

CONCLUSIONS

Point-of-care assessment of platelet reactivity is feasible in the ED and may facilitate the rapid rule-out of ACS in patients with prolonged closure times.

Coronary computed tomography angiography in the assessment of acute chest pain in the emergency room

The coronary computed tomography angiography has recently emerged as an accurate diagnostic tool in the evaluation of coronary artery disease, providing diagnostic and prognostic data that correlate directly with the data provided by invasive coronary angiography. The association of recent technological developments has allowed improved temporal resolution and better spatial coverage of the cardiac volume with significant reduction in radiation dose, and with the crucial need for more effective protocols of risk stratification of patients with chest pain in the emergency room, recent evaluation of the computed tomography coronary angiography has been performed in the setting of acute chest pain, as about two thirds of invasive coronary angiographies show no significantly obstructive coronary artery disease. In daily practice, without the use of more efficient technologies, such as coronary angiography by computed tomography, safe and efficient stratification of patients with acute chest pain remains a challenge to the medical team in the emergency room.

Recently, several studies, including three randomized trials, showed favorable results with the use of this technology in the emergency department for patients with low to intermediate likelihood of coronary artery disease. In this review, we show data resulting from coronary angiography by computed tomography in risk stratification of patients with chest pain in the emergency room, its diagnostic value, prognosis and cost-effectiveness and a critical analysis of recently published multicenter studies.

Role of imaging for acute chest pain syndromes

Acute chest pain suggestive of ischemic cardiac origin, with a normal or nondiagnostic electrocardiogram and negative initial cardiac markers for myocardial necrosis represent a significant diagnostic dilemma for clinicians. Multiple imaging modalities play a pivotal role in early diagnosis and safe discharge of these patients. In this review, we compare the current imaging modalities available for these patients including their diagnostic accuracy, feasibility, and cost effectiveness. Acute rest myocardial perfusion imaging significantly improves the clinical outcome in these patients and reduces the overall cost when incorporated into the decision making pathway. The choice of imaging modality recommended should be based on local institutional expertise and the overall clinical presentation. The imaging modality with high diagnostic accuracy and negative predictive value will provide for precise risk stratification which is important to clinical decision making, including patients who require admission to the hospital and those who can be safely discharged.

The Big Picture: Evidence Base and Current Trials in Cardiac CT

Cardiac computed tomography angiography (CCTA) has technically matured into a robust imaging modality for various cardiac disorders. Whereas early trials focused on assessment of the efficacy of CCTA in comparison with established recommended methods, current research efforts focus on the effectiveness of the technique in specific clinical scenarios. In this article, we provide an overview of recent technology advances, describe major clinical scenarios in which CCTA has been evaluated, and detail pertinent evidence from completed or ongoing clinical trials, including its use to investigate acute chest pain, its use among patients with stable chest pain syndrome, and its prognostic value for the occurrence of cardiovascular events.

Salhi R, Hollander JE. Relationship between body mass index and prognosis of patients presenting with potential acute coronary syndromes

OBJECTIVES

Studies examining the relationship between obesity and acute coronary syndrome (ACS) have been limited to patients with confirmed diagnoses. The authors sought to determine the relationship between body mass index (BMI) and 30-day cardiovascular events in emergency department (ED) patients with potential ACS.

METHODS

This was a secondary analysis of a prospective cohort study of patients who presented to the ED with potential ACS. Patients were stratified according to their BMI: underweight (BMI < 18.49 kg/m(2) ), normal weight (BMI = 18.5 to 24.99 kg/m(2) ), overweight (BMI = 25 to 29.99 kg/m(2) ), obese (BMI = 30 to 34.99 kg/m(2) ), and very obese (BMI > 35 kg/m(2) ). The primary outcome was acute myocardial infarction (AMI), death, or revascularization within 30 days of presentation. A logistic regression analysis was used to adjust for confounding variables and adjusted odds ratios (aOR) with 95% confidence intervals (CIs) are presented for cardiac events and readmission outcomes.

RESULTS

Of the 3,946 patients included in this study, 73 (1.9%) were underweight, 911 (23%) were normal weight, 1,199 (30.4%) were overweight, 872 (22.1%) were obese, and 891 (22.6%) were very obese. Although increased levels of obesity were associated with a greater number of cardiac risk factors, there was no difference in 30-day cardiovascular events between those of normal weight and underweight (aOR = 1.1; 95% CI = 0.4 to 2.7), overweight (aOR = 1.0; 95% CI = 0.7 to 1.4), obese (aOR = 1.2; 95% CI = 0.8 to1.7), or very obese (aOR = 0.8; 95% CI = 0.5 to 1.3). Those who were underweight were more likely to be readmitted within 30 days (aOR = 1.9; 95% CI = 1.0 to 3.7), and those who were very obese were less likely to be readmitted within 30 days (aOR = 0.7; 95% CI = 0.5 to 0.9).

CONCLUSIONS

Among patients who present to the ED with potential ACS, BMI is not associated with higher risk of cardiovascular outcomes at 30 days.

HEART score to further risk stratify patients with low TIMI scores

OBJECTIVE

The ability to risk stratify patients presenting to the emergency department (ED) with potential acute coronary syndrome (ACS) is critical. The thrombolysis in myocardial infarction (TIMI) risk score can risk stratify ED patients with potential ACS but cannot identify patients safe for ED discharge. The symptom-based HEART score identifies very low-risk patients. Our hypothesis was that patients with a TIMI score of 0 or 1 may be stratified further with the HEART score to identify a group of patients at less than 1% risk of 30-day cardiovascular events.

METHODS

We conducted a secondary analysis of a prospective cohort study in a tertiary care hospital ED. Patients with potential ACS who were >30 years of age were included. Data collected included demographics, history, electrocardiogram, laboratories, and components of the TIMI and HEART scores. Follow-up was conducted by structured record review and phone. The main outcome was a composite of death, acute myocardial infarction, or revascularization at 30 days.

RESULTS

There were 8815 patients enrolled (mean age, 52.8 ± 15.1 years; 57% women, and 69% black). At 30 days, the composite event rate was 8.0% (660 patients): 108 deaths, 410 acute myocardial infarction, and 301 revascularizations. Of the 485 patients with both a TIMI score of 0 and a HEART score of 0, there were no cardiovascular events (95% confidence interval, 0-0.8%); but no other score combination had an upper limit confidence interval less than 1%.

CONCLUSION

At all levels of TIMI score, the HEART score was able to further substratify patients with respect to 30-day risk. A HEART score of 0 in a patient with a TIMI of 0 identified a group of patients at less than 1% risk for 30-day adverse events.

Diagnostic performance of resting CT myocardial perfusion in patients with possible acute coronary syndrome

OBJECTIVE

Coronary CT angiography has high sensitivity, but modest specificity, to detect acute coronary syndrome. We studied whether adding resting CT myocardial perfusion imaging improved the detection of acute coronary syndrome.

SUBJECTS AND METHODS

Patients with low-to-intermediate cardiac risk presenting with possible acute coronary syndrome received both the standard of care evaluation and a research thoracic 64-MDCT examination. Patients with an obstructive (> 50%) stenosis or a nonevaluable coronary segment on CT were diagnosed with possible acute coronary syndrome. CT perfusion was determined by applying gray and color Hounsfield unit maps to resting CT angiography images. Adjudicated patient diagnoses were based on the standard of care and 3-month follow-up. Patient-level diagnostic performance for acute coronary syndrome was calculated for coronary CT, CT perfusion, and combined techniques.

RESULTS

A total of 105 patients were enrolled. Of the nine (9%) patients with acute coronary syndrome, all had obstructive CT stenoses but only three had abnormal CT perfusion. CT perfusion was normal in all other patients. To detect acute coronary syndrome, CT angiography had 100% sensitivity, 89% specificity, and a positive predictive value of 45%. For CT perfusion, specificity and positive predictive value were each 100%, and sensitivity was 33%. Combined cardiac CT and CT perfusion had similar specificity but a higher positive predictive value (100%) than did CT angiography.

CONCLUSION

Resting CT perfusion using CT angiographic images may have high specificity and may improve CT positive predictive value for acute coronary syndrome without added radiation and contrast. However, normal resting CT perfusion cannot exclude acute coronary syndrome.

Reduction in observation unit length of stay with coronary computed tomography angiography depends on time of emergency department presentation

OBJECTIVES

Prior studies demonstrating shorter length of stay (LOS) from coronary computed tomography angiography (CCTA) relative to stress testing in emergency department (ED) patients have not considered time of patient presentation. The objectives of this study were to determine whether low-risk chest pain patients receiving stress testing or CCTA have differences in ED plus observation unit (OU) LOS and if there are disparities in testing modality use, based on the time of patient presentation to the ED.

METHODS

The authors examined a cohort of low-risk chest pain patients evaluated in an ED-based OU using prospective and retrospective OU registry data. During the study period, stress testing and CCTA were both available from 08:00 to 17:00 hours. CCTA was not available on weekends, and therefore only subjects presenting on weekdays were included. Cox regression analysis was used to model the effect of testing modality (stress testing vs. CCTA) on OU LOS. Separate models were fit based on time of patient presentation to the ED using 4-hour blocks beginning at midnight. The primary independent variable was testing modality: stress testing or CCTA. Age, sex, and race were included as covariates. Logistic regression was used to model testing modality choice by time period adjusted for age, sex, and race.

RESULTS

Over the study period, 841 subjects presented Monday through Friday. Median LOS was 18.0 hours (interquartile range [IQR] = 11.7 to 22.9 hours). Objective cardiac testing was completed in 788 of 841 (94%) patients, with 496 (63%) receiving stress testing and 292 (37%) receiving CCTA. After age, race, and sex were adjusted for, patients presenting between 08:00 and 11:59 hours not only had a shorter LOS associated with CCTA (p < 0.0001), but also had a greater likelihood of being tested by CCTA (p = 0.001). None of the other time periods had significant differences in LOS or testing modality choice for CCTA relative to stress testing.

CONCLUSIONS

In an OU setting with weekday and standard business hours CCTA availability, CCTA testing was associated with shorter LOS among low-risk chest pain patients only in patients presenting to the ED between 08:00 and 11:59 hours. That time period was also associated with a greater likelihood of being tested by CCTA, suggesting that ED providers may have intuited the inability of CCTA to shorten LOS during other times.

Triage of patients presenting with chest pain to the emergency department: implementation of coronary CT angiography in a large urban health care system

OBJECTIVE

There is growing evidence supporting the use of coronary CT angiography (CTA) to triage patients in the emergency department (ED) with acute chest pain and low risk of acute coronary syndrome (ACS). We hypothesized that coronary CTA can guide early management and safely discharge patients by introducing a dedicated patient management protocol.

SUBJECTS AND METHODS

We conducted a prospective cohort study in three EDs of a large health care system (> 1300 beds). Five hundred twenty-nine patients (mean age, 52.1 years; 56% women) with chest pain, negative cardiac enzyme results, normal or nondiagnostic ECG findings, and a thrombolysis in myocardial infarction (TIMI) risk score of 2 or less were admitted and underwent CTA. A new dedicated chest pain triage protocol (levels 1-5) was implemented. On the basis of CTA findings, patients were stratified into one of the following four groups: 0, low (negative CTA findings); 1, mild (1-49% stenosis); 2, moderate (50-69% stenosis); or 3, severe (≥ 70% stenosis) risk of ACS. Outcome measures included major adverse cardiac events (MACEs) during the first 30 days after CTA, downstream testing results, and length of stay (LOS). LOS was compared before and after implementation of our chest pain triage protocol.

RESULTS

Three hundred seventeen patients (59.9%) with negative CTA findings and 151 (28.5%) with mild stenosis were discharged from the ED with a very low downstream testing rate and a very low MACE rate (negative predictive value = 99.8%). Twenty-five patients (4.7%) had moderate stenosis (n = 17 undergoing further testing). Thirty-six patients (6.8%) had stenosis of 70% or greater by CTA (n = 34 positive by invasive angiography or SPECT-myocardial perfusion imaging). The sensitivity of CTA was 94%. The rate of MACEs in patients with stenosis of 70% or greater (8.3%) was significantly higher (p < 0.001) than in patients with negative CTA findings (0%) or those with mild stenosis (0.2%). A 51% decrease in LOS-from 28.8 to 14.0 hours--was noted after implementation of the dedicated chest pain protocol (p < 0.001).

CONCLUSION

Chest pain patients with negative or mild nonobstructive CTA findings can be safely discharged from the ED without further testing. Implementation of a dedicated chest pain triage protocol is critical for the success of a coronary CTA program.

Risk stratification in chest pain patients undergoing nuclear stress testing: the Erlanger Stress Score

BACKGROUND

Studies have individually reported the relationship of age, cardiac risk factors, and history of preexisting coronary artery disease (CAD) for predicting acute coronary syndromes in chest pain patients undergoing cardiac stress testing. In this study, we investigate the interplay of all these factors on the incidence of acute coronary syndromes to develop a tool that may assist physicians in the selection of appropriate chest pain patients for stress testing.

METHODS

Retrospective analysis of a prospectively acquired database of consecutive chest pain patients undergoing nuclear stress testing. Backward stepwise logistic regression was used to develop a model for predicting risk of 30-day acute coronary events (ACE) using information obtained from age, sex, cardiac risk factors, and history of preexisting CAD.

RESULTS

A total of 800 chest pain patients underwent nuclear stress testing. ACE occurred in 74 patients (9.3%). Logistic regression analysis found only 6 factors predictive of ACE: age, male sex, preexisting CAD, diabetes, and hyperlipidemia. Area under the receiver operator characteristic curve of this model for predicting ACE was 0.767 (95% confidence interval, 0.719-0.815). There were no cases of ACE in the 173 patients with predicted probability estimates ≤2.5% (95% confidence interval, 0%-2.1%).

CONCLUSIONS

A regression model using age, sex, preexisting CAD, diabetes, and hyperlipidemia is predictive of 30-day ACE in chest pain patients undergoing nuclear stress testing. Prospective studies need to be performed to determine whether this model can assist physicians in the selection of appropriate low-to-intermediate risk chest pain patients for nuclear stress testing.

Is it prime time for "rapid comprehensive cardiopulmonary imaging" in the emergency department?

Reducing hospital admissions through improved risk stratification of patients with potential acute coronary syndrome represents a critical focus for reducing health care expenditure. Coronary computed tomographic angiography (CTA) has been used with increasing frequency as part of the evaluation of chest pain in the Emergency Department. In the appropriate group of patients at low to intermediate risk CTA appears to be an excellent evaluation strategy, safely and efficiently allowing for the rapid discharge of patients home.

Non-invasive imaging in coronary artery disease including anatomical and functional evaluation of ischaemia and viability assessment

Coronary artery disease has an important impact on the morbidity and mortality statistics and health economics worldwide. Diagnosis of coronary artery disease is important in risk stratification and guides further management. Invasive coronary angiography is the traditional method of imaging the coronary arteries and remains the gold standard. It detects luminal stenosis but provides little information about the vessel wall or plaques. Besides, not all anatomical lesions are functionally significant. This has lent itself to a wide variety of imaging techniques to identify and assess a flow-limiting stenosis. The approach to diagnosis of coronary artery disease is broadly based on anatomical and functional imaging. Coronary CT and MRI of coronary arteries provide an anatomical assessment of coronary stenosis. Coronary calcium score and coronary CT assess subclinical atherosclerosis by assessing the atherosclerotic plaque burden. The haemodynamic significance of a coronary artery stenosis can be assessed by stress radioisotope studies, stress echocardiography and stress MRI. The more recent literature also focuses on plaque assessment and identification of plaques that are likely to give rise to an acute coronary syndrome. There is an explosion of literature on the merits and limitations of the different imaging modalities. This review article will provide an overview of all the imaging modalities in the diagnosis of coronary artery disease.

Comparison of traditional cardiovascular risk models and coronary atherosclerotic plaque as detected by computed tomography for prediction of acute coronary syndrome in patients with acute chest pain

OBJECTIVES

The objective was to determine the association of four clinical risk scores and coronary plaque burden as detected by computed tomography (CT) with the outcome of acute coronary syndrome (ACS) in patients with acute chest pain. The hypothesis was that the combination of risk scores and plaque burden improved the discriminatory capacity for the diagnosis of ACS.

METHODS

The study was a subanalysis of the Rule Out Myocardial Infarction Using Computer-Assisted Tomography (ROMICAT) trial-a prospective observational cohort study. The authors enrolled patients presenting to the emergency department (ED) with a chief complaint of acute chest pain, inconclusive initial evaluation (negative biomarkers, nondiagnostic electrocardiogram [ECG]), and no history of coronary artery disease (CAD). Patients underwent contrast-enhanced 64-multidetector-row cardiac CT and received standard clinical care (serial ECG, cardiac biomarkers, and subsequent diagnostic testing, such as exercise treadmill testing, nuclear stress perfusion imaging, and/or invasive coronary angiography), as deemed clinically appropriate. The clinical providers were blinded to CT results. The chest pain score was calculated and the results were dichotomized to ≥10 (high-risk) and <10 (low-risk). Three risk scores were calculated, Goldman, Sanchis, and Thrombolysis in Myocardial Infarction (TIMI), and each patient was assigned to a low-, intermediate-, or high-risk category. Because of the low number of subjects in the high-risk group, the intermediate- and high-risk groups were combined into one. CT images were evaluated for the presence of plaque in 17 coronary segments. Plaque burden was stratified into none, intermediate, and high (zero, one to four, and more than four segments with plaque). An outcome panel of two physicians (blinded to CT findings) established the primary outcome of ACS (defined as either an acute myocardial infarction or unstable angina) during the index hospitalization (from the presentation to the ED to the discharge from the hospital). Logistic regression modeling was performed to examine the association of risk scores and coronary plaque burden to the outcome of ACS. Unadjusted models were individually fitted for the coronary plaque burden and for Goldman, Sanchis, TIMI, and chest pain scores. In adjusted analyses, the authors tested whether the association between risk scores and ACS persisted after controlling for the coronary plaque burden. The prognostic discriminatory capacity of the risk scores and plaque burden for ACS was assessed using c-statistics. The differences in area under the receiver-operating characteristic curve (AUC) and c-statistics were tested by performing the -2 log likelihood ratio test of nested models. A p value <0.05 was considered statistically significant.

RESULTS

Among 368 subjects, 31 (8%) subjects were diagnosed with ACS. Goldman (AUC = 0.61), Sanchis (AUC = 0.71), and TIMI (AUC = 0.63) had modest discriminatory capacity for the diagnosis of ACS. Plaque burden was the strongest predictor of ACS (AUC = 0.86; p < 0.05 for all comparisons with individual risk scores). The combination of plaque burden and risk scores improved prediction of ACS (plaque + Goldman AUC = 0.88, plaque + Sanchis AUC = 0.90, plaque + TIMI AUC = 0.88; p < 0.01 for all comparisons with coronary plaque burden alone).

CONCLUSIONS

Risk scores (Goldman, Sanchis, TIMI) have modest discriminatory capacity and coronary plaque burden has good discriminatory capacity for the diagnosis of ACS in patients with acute chest pain. The combined information of risk scores and plaque burden significantly improves the discriminatory capacity for the diagnosis of ACS.

Cholesteryl esters associated with acyl-CoA:cholesterol acyltransferase predict coronary artery disease in patients with symptoms of acute coronary syndrome

OBJECTIVES

Identifying the likelihood of a patient having coronary artery disease (CAD) at the time of emergency department (ED) presentation with chest pain could reduce the need for stress testing or coronary imaging after myocardial infarction (MI) has been excluded. The authors aimed to determine if a novel cardiac biomarker consisting of plasma cholesteryl ester (CE) levels typically derived from the activity of the enzyme acyl-CoA:cholesterol acyltransferase (ACAT2) are predictive of CAD in a clinical model.

METHODS

A single-center prospective cohort design enrolled participants with symptoms of acute coronary syndrome (ACS) undergoing coronary computed tomography angiography (CCTA) or invasive angiography. Plasma samples were analyzed for CE composition with mass spectrometry. The primary endpoint was any CAD determined at angiography. Multivariable logistic regression analyses were used to estimate the relationship between the sum of the plasma concentrations from cholesteryl palmitoleate (16:1) and cholesteryl oleate (18:1) (defined as ACAT2-CE) and the presence of CAD. The added value of ACAT2-CE to the model was analyzed comparing the C-statistics and integrated discrimination improvement (IDI).

RESULTS

The study cohort was composed of 113 participants with a mean (± standard deviation [SD]) age of 49 (±11.7) years, 59% had CAD at angiography, and 23% had an MI within 30 days. The median (interquartile range [IQR]) plasma concentration of ACAT2-CE was 938 μmol/L (IQR = 758 to 1,099 μmol/L) in patients with CAD and 824 μmol/L (IQR = 683 to 998 μmol/L) in patients without CAD (p = 0.03). When considered with age, sex, and the number of conventional CAD risk factors, ACAT2-CE levels were associated with a 6.5% increased odds of having CAD per 10 μmol/L increase in concentration. The addition of ACAT2-CE significantly improved the C-statistic (0.89 vs. 0.95, p = 0.0035) and IDI (0.15, p < 0.001) compared to the reduced model. In the subgroup of low-risk observation unit patients, the CE model had superior discrimination compared to the Diamond-Forrester classification (IDI = 0.403, p < 0.001).

CONCLUSIONS

Plasma levels of ACAT2-CE have strong potential to predict a patient's likelihood of having CAD when considered in a clinical model but not when used alone. In turn, a clinical model containing ACAT2-CE could reduce the need for cardiac imaging after the exclusion of MI.