Acute coronary syndromes in the emergency department: diagnostic characteristics, tests, and challenges

Comparison of two strategies in a chest pain unit: stress echocardiography and multidetector computed tomography

INTRODUCTION AND OBJECTIVES

This study aimed to compare stress echocardiography (SE) and multidetector computed tomography (MCT) in patients admitted to a chest pain unit to detect acute coronary syndrome (ACS).

METHODS

A total of 203 patients with ≥ 1 cardiovascular risk factor, no ischemic electrocardiogram changes and negative biomarkers were randomized to SE (n=103) or MTC (n=100). The primary endpoint was a combination of hard events (death and nonfatal myocardial infarction), revascularizations, and readmissions during follow-up. The secondary endpoint was the cost of the 2 strategies.

RESULTS

Invasive angiography was performed in 61 patients (34 [33%] in the SE group and in 27 [27%] in the MCT group, P=.15). A final diagnosis of ACS was made in 53 patients (88% vs 85%, P=.35). There were no significant differences between groups in the primary endpoint (42% vs 41%, P=.91), or in hard events (5% vs 7%, P=.42). There were no significant differences in overall cost, but costs were lower in patients with negative SE than in those with negative MCT (€557 vs €706, P <.02).

CONCLUSIONS

No significant differences were found in efficacy and safety for the stratification of patients with a low to moderate probability of ACS admitted to a chest pain unit. The cost of the 2 strategies was similar, but cost was significantly lower for SE on comparison of negative studies.

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.

Computed Tomographic Angiography for Risk Stratification in Patients with Acute Chest Pain - The Triple Rule-out Concept in the Emergency Department

BACKGROUND

Acute chest pain is one of the most common reasons for Emergency Department (ED) visits and hospital admissions. As this could represent the first symptom of a lifethreatening condition, urgent identification of the etiology of chest pain is of utmost importance in emergency settings. Such high-risk conditions that can present with acute chest pain in the ED include Acute Coronary Syndromes (ACS), Pulmonary Embolisms (PE) and Acute Aortic Syndromes (AAS).

DISCUSSION

The concept of Triple Rule-out Computed Tomographic Angiography (TRO-CTA) for patients presenting with acute chest pain in the ED is based on the use of coronary computed tomographic angiography as a single imaging technique, able to diagnose or exclude three lifethreatening conditions in one single step: ACS, AAS and PE. TRO-CTA protocols have been proved to be efficient in the ED for diagnosis or exclusion of life-threatening conditions and for differentiation between various etiologies of chest pain, and application of the TRO-CTA protocol in the ED for acute chest pain of uncertain etiology has been shown to improve the further clinical evaluation and outcomes of these patients.

CONCLUSION

This review aims to summarize the main indications and techniques used in TRO protocols in EDs, and the role of TRO-CTA protocols in risk stratification of patients with acute chest pain.

Prevalence of Acute Coronary Syndrome in Patients Suspected for Pulmonary Embolism or Acute Aortic Syndrome: Rationale for the Triple Rule-Out Concept

BACKGROUND

The aims of the study were to evaluate the prevalence of acute coronary syndrome (ACS) among patients presenting with atypical chest pain who are evaluated for acute aortic syndrome (AAS) or pulmonary embolism (PE) with computed tomoangiography (CTA) and discuss the rationale for the use of triple rule-out (TRO) protocol for triaging these patients.

METHODS

This study is a retrospective analysis of patients presenting with atypical chest pain and evaluated with thoracic (CTA), for suspicion of AAS/PE. Two physicians reviewed patient files for demographic characteristics, initial CT and final clinical diagnosis. Patients were classified according to CTA finding into AAS, PE and other diagnoses and according to final clinical diagnosis into AAS, PE, ACS and other diagnoses.

RESULTS

Four hundred and sixty-seven patients were evaluated: 396 (84.8%) patients for clinical suspicion of PE and 71 (15.2%) patients for suspicion of AAS. The prevalence of ACS and AAS was low among the PE patients: 5.5% and 0.5% respectively (P = 0.0001), while the prevalence of ACS and PE was 18.3% and 5.6% among AAS patients (P = 0.14 and P = 0.34 respectively).

CONCLUSION

The prevalence of ACS and AAS among patients suspected clinically of having PE is limited while the prevalence of ACS and PE among patients suspected clinically of having AAS is significant. Accordingly patients suspected for PE could be evaluated with dedicated PE CTA while those suspected for AAS should still be triaged using TRO protocol.

High-sensitive troponin T assay for the diagnosis of acute myocardial infarction: an economic evaluation

Background

Delayed diagnosis and treatment of Acute Myocardial Infarction (AMI) has a major adverse impact on prognosis in terms of both morbidity and mortality. Since conventional cardiac Troponin assays have a low sensitivity for diagnosing AMI in the first hours after myocardial necrosis, high-sensitive assays have been developed. The aim of this study was to assess the cost effectiveness of a high-sensitive Troponin T assay (hsTnT), alone or combined with the heart-type fatty acid-binding protein (H-FABP) assay in comparison with the conventional cardiac Troponin (cTnT) assay for the diagnosis of AMI in patients presenting to the hospital with chest pain.

Methods

We performed a cost-utility analysis (quality adjusted life years-QALYs) and a cost effectiveness analysis (life years gained-LYGs) based on a decision analytic model, using a health care perspective in the Dutch context and a life time time-horizon. The robustness of model predictions was explored using one-way and probabilistic sensitivity analyses.

Results

For a life time incremental cost of 30.70 Euros, use of hsTnT over conventional cTnT results in gain of 0.006 Life Years and 0.004 QALY. It should be noted here that hsTnT is a diagnostic intervention which costs only 4.39 Euros/test more than the cTnT test. The ICER generated with the use of hsTnT based diagnostic strategy comparing with the use of a cTnT-based strategy, is 4945 Euros per LYG and 7370 Euros per QALY. The hsTnT strategy has the highest probability of being cost effective at thresholds between 8000 and 20000 Euros per QALY. The combination of hsTnT and h-FABP strategy’s probability of being cost effective remains lower than hsTnT at all willingness to pay thresholds.

Conclusion

Our analysis suggests that hsTnT assay is a very cost effective diagnostic tool relative to conventional TnT assay. Combination of hsTnT and H-FABP does not offer any additional economic and health benefit over hsTnT test alone.

Evaluation of the diagnostic performance of current and next-generation assays for cardiac troponin I in the BWH-TIMI ED Chest Pain Study

BACKGROUND

Rapid diagnosis of acute coronary syndrome is a clinical and operational priority in busy emergency departments (ED). We examined the performance of an investigational troponin I (TnI) assay with 10-100-times greater sensitivity than current commercial assays.

METHODS

Among patients with non-traumatic chest pain enrolled in the BWH-TIMI ED Chest Pain Study, we measured TnI (n=381) at baseline, 4-6 h, and 12-24 h with an investigational assay (S-TnI; Singulex, detection-limit 0.0002 µg/l, 99th percentile 0.009 µg/l) and a contemporary sensitive assay (TnI-Ultra; Siemens, detection-limit 0.006 µg/l, 99th percentile 0.04 µg/l). Final diagnosis was adjudicated using all diagnostic data and local hospital-based cardiac TnI (Siemens), blinded to investigational cardiac Tn.

RESULTS

The adjudicated diagnosis was myocardial infarction (MI) in 96 patients, unstable angina in 41, and acute non-coronary cardiovascular conditions in 50 patients. Baseline S-TnI was highly sensitive for MI (97%, 95% CI 91-99%) with specificity 81% (95% CI 76-86%) and positive predictive value 63% (95% CI 55-71%). The negative predictive value with S-TnI was 99% (95% CI 96-100%). S-TnI had better diagnostic accuracy than the local assay (area under the curve 0.976 vs. 0.916, p=0.003). Among 20 patients with negative baseline TnI and diagnosis of MI, 19 had elevated baseline S-TnI. Compared to TnI-Ultra, S-TnI trended toward higher sensitivity (97 vs. 94%, p=NS) but did not differ significantly in negative predictive value (99 vs. 98%) or area under the curve (p=0.29).

CONCLUSION

Current and investigational Tn assays substantially increased clinical sensitivity and improved diagnostic accuracy for MI, despite a decline in specificity. A contemporary sensitive assay delivered similar overall accuracy to the investigational test, suggesting that we have reached a point of maximum diagnostic return with increasing analytical sensitivity.

Chest pain of cardiac and noncardiac origin

Chest pain is one of the most common symptoms driving patients to a physician's office or the hospital's emergency department. In approximately half of the cases, chest pain is of cardiac origin, either ischemic cardiac or nonischemic cardiac disease. The other half is due to noncardiac causes, primarily esophageal disorder. Pain from either origin may occur in the same patient. In addition, psychological and psychiatric factors play a significant role in the perception and severity of the chest pain, irrespective of its cause. Chest pain of ischemic cardiac disease is called angina pectoris. Stable angina may be the prelude of ischemic cardiac disease; and for this reason, it is essential to ensure a correct diagnosis. In most cases, further testing, such as exercise testing and angiography, should be considered. The more severe form of chest pain, unstable angina, also requires a firm diagnosis because it indicates severe coronary disease and is the earliest manifestation of acute myocardial infarction. Once a diagnosis of stable or unstable angina is established, and if a decision is made not to use invasive therapy, such as coronary bypass, percutaneous transluminal coronary angioplasty, or stent insertion, effective medical treatment of associated cardiac risk factors is a must. Acute myocardial infarction occurring after a diagnosis of angina greatly increases the risk of subsequent death. Chest pain in women warrants added attention because women underestimate their likelihood to have coronary heart disease. A factor that complicates the clinical assessment of patients with chest pain (both cardiac and noncardiac in origin) is the relatively common presence of psychological and psychiatric conditions such as depression or panic disorder. These factors have been found to cause or worsen chest pain; but unfortunately, they may not be easily detected. Noncardiac chest pain represents the remaining half of all cases of chest pain. Although there are a number of causes, gastroesophageal disorders are by far the most prevalent, especially gastroesophageal reflux disease. Fortunately, this disease can be diagnosed and treated effectively by proton-pump inhibitors. The other types of non-gastroesophageal reflux disease-related noncardiac chest pain are more difficult to diagnose and treat. In conclusion, the cause of chest pain must be accurately diagnosed; and treatment must be pursued according to the cause, especially if the cause is of cardiac origin.

Cardiac computed tomography and magnetic resonance imaging: the clinical use from a cardiologist's perspective

The introduction and continued evolution of cardiac computed tomography and magnetic resonance imaging have added considerable noninvasive diagnostic insight into a wide range of frequently encountered clinical cardiology scenarios. With an increasing range of imaging modalities, and multiple methods of image acquisition in each, a detailed understanding of the clinical question at hand is often necessary to select the proper study and make optimal use of imaging data. We review common cardiac issues from a clinician's perspective, along with the unique role to be played by computed tomography and magnetic resonance imaging in each condition. This review will hopefully facilitate a strong dialogue between imagers and managing clinicians, creating a shared knowledge of both the capabilities of imaging and the management challenges that treating clinicians face.

Computed tomographic coronary artery calcium assessment for evaluating chest pain in the emergency department: long-term outcome of a prospective blind study

OBJECTIVE

To determine the long-term outcome of computed tomographic (CT) quantification of coronary artery calcium (CAC) used as a triage tool for patients presenting with chest pain to an emergency department (ED).

PATIENTS AND METHODS

Patients (men aged 30-62 years and women aged 30-65 years) with chest pain and low-to-moderate probability of coronary artery disease underwent both conventional ED chest pain evaluation and CT CAC assessment prospectively. Patients' physicians were blinded to the CAC results. The results of the conventional evaluation were compared with CAC findings on CT, and the long-term outcome in patients undergoing CT CAC assessment was established. Primary end points (acute coronary syndrome, death, fatal or nonfatal non-ST-segment elevation myocardial infarction, fatal or nonfatal ST-segment elevation myocardial infarction) and secondary outcomes (coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, coronary stenting, or a combination thereof) were obtained when the patient was dismissed from the ED or hospital and then at 30 days, 1 year, and 5 years.

RESULTS

Of the 263 study patients, 133 (51%) had a CAC score of zero. This absence of CAC correlated strongly with the likelihood of noncardiac chest pain. Among 133 patients with a CAC score of zero, only 1 (<1%) had cardiac chest pain. Conversely, of the 31 patients shown to have cardiac chest pain, 30 (97%) had evidence of CAC on CT. When a CAC cutoff score of 36 was used, as suggested by receiver operating characteristic analysis, sensitivity was 90%; specificity, 85%; positive predictive value, 44%; and negative predictive value, 99%. During long-term follow-up, patients without CAC experienced no cardiac events at 30 days, 1 year, and 5 years.

CONCLUSION

Findings suggest that CT CAC assessment is a powerful adjunct in chest pain evaluation for the population at low-to-intermediate risk. Absent or minimal CAC in this population makes cardiac chest pain extremely unlikely. The absence of CAC suggests an excellent long-term (5-year) prognosis, with no primary or secondary cardiac outcomes occurring in study patients at 5-year follow-up.

High-risk chief complaints I: chest pain--the big three

Chest pain is one of the most frequently seen chief complaints in patients presenting to emergency departments, and is considered to be a "high-risk" chief complaint. The differential diagnosis for chest pain is broad, and potential causes range from the benign to the immediately life-threatening. Although many (if not most) emergency department patients with chest pain do not have an immediately life-threatening condition, correct diagnoses can be difficult to make, incorrect diagnoses may lead to catastrophic therapies, and failure to make a timely diagnosis may contribute to significant morbidity and mortality. Several atraumatic "high-risk" causes of chest pain are discussed in this article, including myocardial infarction and ischemia, thoracic aortic dissection, and pulmonary embolism. Also included are brief discussions of tension pneumothorax, esophageal perforation, and cardiac tamponade.

Triple-rule-out CT angiography for evaluation of acute chest pain and possible acute coronary syndrome

Triple-rule-out (TRO) computed tomographic (CT) angiography can provide a cost-effective evaluation of the coronary arteries, aorta, pulmonary arteries, and adjacent intrathoracic structures for the patient with acute chest pain. TRO CT is most appropriate for the patient who is judged to be at low to intermediate risk for acute coronary syndrome (ACS) and whose symptoms may also be attributed to acute pathologic conditions of the aorta or pulmonary arteries. Although a regular cardiac rhythm remains an important factor in coronary CT image quality, newer CT scanners with 64 or more detector rows afford rapid electrocardiographically (ECG) gated imaging to provide high-quality TRO CT studies in patients with a heart rate of up to 80 beats per minute. Injection of iodinated contrast material (< or = 100 mL) is tailored to provide simultaneous high levels of arterial enhancement in the coronary arteries and aorta (> 300 HU) and in the pulmonary arteries (> 200 HU). To limit radiation exposure, the TRO CT examination does not include the entire chest but is constrained to incorporate the aortic arch down through the heart. Scanning parameters, including prospective ECG tube current modulation and prospective ECG gating with the "step-and-shoot" technique, are tailored to reduce radiation exposure (optimally, 5-9 mSv). When performed with appropriate attention to timing and technique, TRO CT provides coronary image quality equal to that of dedicated coronary CT angiography and pulmonary arterial images that are free of motion artifact related to cardiac pulsation. In an appropriately selected emergency department patient population, TRO CT can safely eliminate the need for further diagnostic testing in over 75% of patients.

Myocardial perfusion imaging with contrast echocardiography

Advances in myocardial perfusion imaging have firmly established the use of noninvasive techniques capable of providing useful information over a broad range of diagnostic and therapeutic cardiovascular problems. Evaluating regional myocardial perfusion abnormalities is a cornerstone for the diagnosis of coronary artery disease, risk assessment in those with known disease, and determination of myocardial viability. The clinical use of myocardial perfusion imaging and the current limitations of existing techniques continue to promote the development of new technologies capable of assessing microvascular and capillary perfusion abnormalities on a global myocardial level. Myocardial contrast echocardiography is an emerging technique capable of rapidly assessing myocardial perfusion at the capillary level in many different clinical settings. This article focuses on myocardial contrast-enhanced ultrasound perfusion techniques, emphasizing the unique information this modality provides compared with other noninvasive perfusion imaging techniques.

Sixty-four–slice multidetector computed tomography: the future of ED cardiac care

Multidetector computed tomography (MDCT) imaging, a technological advance over traditional CT, is a promising possible alternative to cardiac catheterization for evaluating patients with chest pain in the emergency department (ED). In comparison with traditional CT, MDCT offers increased spatial and temporal resolution that allows reliable visualization of the coronary arteries. In addition, a "triple scan," which includes evaluation for pulmonary embolism and thoracic aortic dissection, can be incorporated into a single study. This test will enable emergency physicians to rapidly evaluate patients for life-threatening illnesses and may allow safer and earlier discharges of many patients with chest pain in comparison with a traditional rule-out protocol. In this article, we will highlight the technological advances of MDCT imaging, review the literature on coronary angiography via MDCT, and discuss the future of this technology as it relates to the ED.

Effects of socioeconomic status on mortality after acute myocardial infarction

PURPOSE

To assess the effects of socioeconomic status on mortality in patients with acute myocardial infarction.

MATERIAL AND METHODS

We studied a retrospective cohort of 5622 patients who presented to a hospital emergency department with an initial episode of acute myocardial infarction between April 1998 and March 2002 in the Province of Alberta, Canada. Our main outcome measure was 1-year all-cause mortality following the index emergency department visit; we used socioeconomic status (measured by neighborhood median household income) as our main predictor after controlling for patient and hospital characteristics and revascularization.

RESULTS

Socioeconomic status profoundly affected the rate of emergency department presentation and the process and outcome of acute myocardial infarction care. In patients belonging to the lowest versus the highest socioeconomic status quartile, the risk of presenting to the emergency department was 72% higher (P <.001); at 1 year, revascularization was lower (36% vs 48%, P <.001), and mortality higher (19.1% vs 9.1%, P <.001). Socioeconomic status was independently associated with 1-year mortality after adjustment for baseline characteristics and 1-year revascularization, and socioeconomic status was especially influential in non-revascularized patients.

CONCLUSIONS

Given the influence of socioeconomic status on mortality after acute myocardial infarction and the key role of revascularization in modulating this relationship, our study has important implications for access to and process of cardiac care.