Clinical assessment of chest pain and guidelines for imaging

European Journal of Radiology 81 (2012) 3663–3668

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European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad

Review

Clinical assessment of chest pain and guidelines for imaging J. Gruettner a,∗ , T. Henzler b , T. Sueselbeck a , C. Fink b , M. Borggrefe a , T. Walter a a b

1st Department of Medicine (Cardiology), University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany

a r t i c l e

i n f o

Article history: Received 11 January 2011 Accepted 14 January 2011 Keywords: Emergency room Chest Pain Unit Coronary syndrome Reperfusion therapy Risk stratification Triple rule out Chest pain

a b s t r a c t For many emergency facilities, risk assessment of patients with diffuse chest pain still poses a major challenge. In their currently valid recommendations, the international cardiological societies have defined a standardized assessment of the prognostically relevant cardiac risk criteria. Here the classic sequence of basic cardiac diagnostics including case history (cardiac risk factors), physical examination (haemodynamic and respiratory vital parameters), ECG (ST segment analysis) and laboratory risk markers (troponin levels) is paramount. The focus is, on the one hand, on timely indication for percutaneous catheterization, especially in patients at high cardiac risk with or without ST-segment elevation in the ECG, and, on the other hand, on the possibility of safely discharging patients with intermediate or low cardiac risk after non-invasive exclusion of a coronary syndrome. For patients in the intermediate or low risk group, physical or pharmacological stress testing in combination with scintigraphy, echocardiography or magnetic resonance imaging is recommended in addition to basic diagnostics. Moreover, the importance of non-invasive coronary imaging, primarily cardiac CT angiography (CCTA), is increasing. Current data show that in intermediate or low risk patients this method is suitable to reliably rule out coronary heart disease. In addition, attention is paid to the major differential diagnoses of acute coronary syndrome, particularly pulmonary embolism and aortic dissection. Here the diagnostic method of choice is thoracic CT, possibly also in combination with CCTA aiming at a triple rule-out. © 2011 Elsevier Ireland Ltd. All rights reserved.

1. Introduction For many years, cardiovascular disease has been the most frequent cause of death in the industrialized countries all over the world. In the USA and in Europe, every year approximately 15 millions of patients are treated in emergency rooms for suspected myocardial infarction [1]. The rate of actually evidenced acute coronary syndromes (ACS) amounts to 10–20% of these cases; approximately half of the patients with undefined chest pain are discharged from the emergency room on the day of admission after exclusion of ACS or relevant differential diagnoses [2]. Risk assessment of these patients, quick diagnosis and reliable determination of eligibility for discharge still cause substantial problems for the emergency facilities. Prior to the worldwide implementation of chest pain units more than 20 years ago, the rate of undiagnosed ACS amounted to 5–15% [3]. Markedly, more up-to-date studies, however, reveal that in spite of enormous development and experience in the diagnosis and therapy of ACS the risk of uncontrolled or premature discharges is today still quite relevant at 2–5% [4–6]. For

∗ Corresponding author at: 1st Department of Medicine, University Medical Center Mannheim, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany. E-mail address: [email protected] (J. Gruettner). 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.01.063

prognostically important differential diagnoses such as pulmonary embolism, high rates of misjudgements are likewise documented, unchanged over many years [7]. Emergency medicine experts receive important support in the diagnosis and therapy of ACS and its differential diagnoses from permanently updated guidelines by national and international professional societies [8–13]. In addition, broad national schemes such as nationwide certification of chest pain units in Germany attempt to systematically counteract the risk of misdiagnoses in the assessment of acute chest pain.

2. Differential diagnoses Differential diagnoses of the ACS are of particular importance in the context of unclear chest pain (Table 1). They include noncoronary cardiac causes such as valve defects, cardiomyopathies, peri- and myocarditis, hypertensive heart disease and pulmonary embolism underlying acute right ventricular dysfunction. In addition, vascular (aortic dissection), pulmonary (pneumothorax, pleuritis) as well as neuropathic, oesophageal, gastrointestinal, musculoskeletal and psychogenic conditions must be considered. Given the plethora of possible causes, it is expedient to sort the differential diagnoses by priority. The highest risk conditions are, apart from coronary syndrome, pulmonary embolism and aortic dissection. These conditions must be quickly and reliably either

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Table 1 Differential diagnoses of acute coronary syndrome. High risk

Intermediate risk

Low risk

Pulmonary embolism Aortic dissection

Valvular disease Cardiomyopathy Pericarditis/Myocarditis Hypertension Pneumothorax

Pleuritis Neuropathy Oesophageal disease Gastrointestinal disease Musculoskeletal injury Psychogenic condition

detected or excluded, respectively. Intermediate risk results from non-coronary cardiac causes and pneumothorax, conditions which must be reliably diagnosed but whose prognosis generally remains the same over the treatment period. The risk is rather low in most neuropathic, oesophageal, gastrointestinal, musculoskeletal and psychogenic conditions. They are often diagnoses of exclusion, and treatment may often be continued in an outpatient setting. In many cases, however, reliable differential diagnosis after exclusion of a coronary syndrome is not possible at the time of discharge [14]. 3. Risk stratification For risk stratification of patients suspected of coronary syndrome, precise determination and assessment of prognostically relevant criteria is the mainstay. Prime elements of this synopsis are anamnestic, clinical, electro- and echocardiographical as well as laboratory parameters. 3.1. Clinical symptoms In general, chest pain is the leading symptom in patients with ACS diagnosed upon admission. There is an agreement that assessment of the pain character usually indicates the diagnostic direction but is unreliable as an exclusive tool for initial assessment and to be evaluated with caution [15]. Table 2 gives an overview of typical and atypical symptoms of angina pectoris. Retrosternal, long-lasting and nitrate-sensitive rest pain – described by Braunwald – emanating into arm, jaws or abdomen, in combination with vegetative symptoms such as dyspnoea, cold sweat and nausea, is considered as typical angina pectoris [16]. The intensity of the complaints likewise seems to be correlated to a certain degree with the risk of myocardial infarction and death [17]. Pain lasting for more than 20 min or persisting is particularly suggestive of infarction. Furthermore, triggering by stress and cold is considered as typical for angina pectoris. In women, diabetics and generally the elderly, the aforesaid symptoms are often expressed less strongly or less typically. Symptoms considered as rather atypical for angina pectoris include brief pain (a few seconds to minutes), small area of pain (few cm2 ), mechanical triggering (palpation, rotation) and position-dependence of the pain. For differential diagnosis, the breath-dependent pain symptomatology, with the focus on inspiration, in pulmonary embolism and the sharp immediate pain with emanation into neck and jaws in proximal, into back and abdomen

Table 2 Angina pectoris. Typical symptoms

Atypical symptoms

Prolonged angina (>20 min) Recurrent angina Retrosternal extension Emanating into arm, jaws or abdomen Triggering by stress or cold Nitrate-sensitive angina Vegetative symptoms

Brief pain (few seconds or minutes) Position-dependence Small area of pain (few cm2 ) Mechanical triggering

in distal aortic dissection, are of interest. However, even in these cases the pain frequently manifests atypically, sometimes only as a transient episode which does not appear very impressive upon admission. 3.2. Risk anamnesis In the extended anamnesis of suspected ACS, prognostically important cardiac risk factors include diabetes mellitus, arterial hypertension, hypercholesterinaemia, nicotine abusus, family history and advanced age, with diabetes mellitus being of special importance. Recent coronary events such as myocardial infarction or coronary procedures such as percutaneous catheterization (PCI) or coronary bypass surgery (CABG) in the preceding weeks or months likewise significantly increase the prognostic risk in the context of acute complaints. For differential diagnosis, patients must be questioned about previous infections, (especially those which could cause acute chest pain such as peri-/myocarditis and pleuritis), pulmonary embolisms and deep vein thromboses, as well as previous oesophageal, gastroenterological, orthopaedic or possibly psychiatric conditions. 3.3. Clinical findings Systematic physical examination of patients suspected of ACS includes in particular the classic examination techniques for the assessment of haemodynamics and cardiac insufficiency. Blood pressure and heart rate must be documented immediately. In auscultation, signs of congestion in the pulmonary veins, but with regard to differential diagnosis also findings typical for valvular diseases (aortic stenosis?), are of particular importance. Furthermore, indications of deep vein thromboses (pulmonary embolism?), of central or peripheral arterial occlusions (aortic dissection?) and other cardinal findings are important. Generally, in the context of acute chest pain, haemodynamically or respiratorically unstable patients are to be considered, according to all the above guidelines, as high risk patients and urgently subjected to heart catheterization [8,10,11]. 3.4. Electrocardiography The 12-lead ECG has top priority in the basic diagnostics of ACS, and according to the guidelines it must be taken no later than 10 min after the patient’s arrival in the emergency room. In the context of angina pectoris complaints, an ST elevation myocardial infarction (STEMI) is considered as evidenced if an ST-segment elevation of more than 0.2 mV is detected in more than two precordial leads, or of more than 0.1 mV in more than two limb leads or a newly occurred complete left bundle branch block is found. Because of the particularly poor prognosis of STEMI, this constellation justifies immediate reperfusion therapy without any further additional diagnostics [9,12,13]. Furthermore, alternating ST-segment changes or persisting ST-segment depressions of more than 0.1 mV are prognostically significant [18]. Specifically, deep T inversions in the precordial leads imply high risk. Furthermore, in the context of chest pain, T-wave negativity seems to be linked to rather moderately increased risk [19]. All in all, compared to ST-segment changes, T-wave negativity is of lower prognostic significance and in particular less specific [20]. Basically, in the context of angina pectoris complaints, all haemodynamically relevant and thus potentially life-threatening cardiac arrhythmias such as ventricular tachyarrhythmias must be considered as absolute high risk-situations with urgent indication for heart catheterization [8,10,11]. Regarding differential diagnosis, in tachycardic arrhythmias, T-wave negativity, right bundle branch block or e.g., SI/QIII type in combination with chest pain pulmonary embolism

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must also be contemplated. Here, however, the specificity of these changes is rather low [21].

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pulmonary embolism [30]. For aortic dissection fewer data are available; here testing for d-dimers can only be a supporting tool in overall clinical assessment [31].

3.5. Echocardiography 4. Non-invasive radiological diagnostics Acute cardiac insufficiency in combination with an ACS has poor prognosis. In the acute setting echocardiography is the most important examination method for imaging of left-ventricular function. In some cases of borderline ST-segment elevation in the ECG, demonstration of regional wall motion abnormalities in the affected segment of the myocardium can corroborate a suspicion of STEMI. But above all, echocardiography is helpful for differential diagnosis of non-coronary heart diseases (valve defects, cardiomyopathies, detection of right-ventricular dysfunction in pulmonary embolism, etc.). For general prognostic assessment of ACS, however, in particular for low risk patients, echocardiography is of minor importance compared to the aforesaid risk parameters [22]. 3.6. Biochemical risk markers Lab chemistry parameters are another mainstay in risk stratification of the ACS. In the guidelines, increased creatine kinase (CK) levels with a significant portion of the CK-MB isoenzyme of more than 5% of total CK are still considered as a valuable marker with prognostic importance for detection of myocardial cell damage as found in myocardial infarctions. In clinical routine, however, CK has been ousted by troponin, which reveals myocardial necrosis with much higher sensitivity and specificity [23,24]. The importance attributed to troponin in the guidelines and current literature is particularly documented by the current terminology of myocardial infarction, which primarily mentions troponin in lieu of creatine kinase, as the cardinal marker of myocardial damage. Positive detection of troponin has the highest prognostic significance among the biomarkers of ACS [25]. Slightly increased troponin values below the limit characteristic for infarction also indicate – albeit limited – cardiac risk [26]. The temporal dynamics of troponin are the basis for important sequences of actions and thus of particular importance in risk stratification of the ACS. Thus, troponin values are only partly reliable during the first hours after onset of the complaints, since troponin becomes detectable only after 3–4 h. On the other hand, it is well-documented that patients with low cardiac risk showing troponin levels in the norm range 6 h after the onset of symptoms have an excellent prognosis [19,26]. Pathologically increased troponin levels may occasionally be found also in non-coronary heart conditions such as peri- and myocarditis or right-ventricular dysfunction in the context of pulmonary embolism, and also in non-cardiac conditions such as sepsis or trauma, more rarely also in acute neurological conditions such as subarachnoidal haemorrhage or ischaemic stroke [27]. Discretely increased troponin levels are sometimes observed in renal insufficiency as well. First experience with new sensitive troponin assays shows, apart from higher sensitivity, markedly decreased specificity in the lower and middle measuring ranges [28,29]. So far, however, there are only very scarce data available on sensitive troponin, and more stringent evaluation for clinical day-to-day routine thus still remains to be performed. Further biomarkers such as myoglobin or CRP play a minor role in emergency diagnostics of the ACS. d-dimers as parameters of acute coagulation activation are usually slightly increased in myocardial infarction, but compared to the biomarkers mentioned above they play no particular role in the diagnosis of ACS. d-dimers are very unspecific, but because of their high sensitivity in pulmonary embolism and, to a limited degree, also in aortic dissection, they have their main use in differential diagnostics. In the extensive literature on the role of d-dimers in pulmonary embolism the view is held almost unanimously that a negative d-dimer value largely excludes acute

Radiological examinations (primarily conventional chest X-ray and computed tomography (CT) of the chest with CT angiography of the pulmonary arteries and thoracic aorta) complement the sequence of risk stratification in particular with regard to differential diagnosis (e.g., pneumothorax, pulmonary embolism). However, more advanced imaging tests like cardiac CT and – albeit limited – cardiac MRI are gaining more and more importance also for primary diagnostics of the ACS. 4.1. Conventional X-ray Conventional chest X-ray is an indispensable part of the basic diagnostics in the emergency room. It is of particular importance in the detection of signs of congestion in the pulmonary veins or of pleural effusions, and apart from that in differential diagnostics (e.g., pneumothorax) [32]. 4.2. Computed tomography For a long time, computed tomography had its value in particular in the detection or exclusion, respectively, of important differential diagnoses such as pulmonary embolism or aortic dissection. With the development and introduction of new CT techniques such as dual-source CT, however, the scope of CT has been significantly extended even into primary diagnostics of the ACS. In this context two methods in particular, coronary calcification scoring and CT angiography of the coronary arteries (coronary CTA), have moved into the focus of CAD diagnostics. Quantification of coronary calcification describes the extent of coronary arteriosclerosis and is correlated – in cases of higher Agatston scores of calcification – with increased cardiac risk. Coronary calcification scoring is rendered important in practice by its high negatively predictive value, which in case of a negative score largely excludes any relevant coronary heart disease [33]. Because of its high negatively predictive value, contrast-enhanced 64-slice coronary CTA likewise has increasing importance for largely reliable exclusion of CAD [34,35]. Both coronary calcification scoring and coronary CTA are thus primarily exclusion methods with only very limited suitability for assessment of manifest coronary stenosis. On the basis of these data, the current American and European guidelines recommend coronary CTA for investigation of unclear chest pain in patients at low to intermediate cardiac risk and non-significant stress test [36,37]. The use of coronary CTA in symptomatic patients with higher cardiac risk or pathological stress testing results is controversial [38]. However, the recently published guidelines about the appropriate use criteria for cardiac CT have greatly expanded the number of potential clinical scenarios in comparison to the original 2006 document including acute and chronic chest pain [39]. Other CT techniques such as positron emission tomography (PET) can be used for certain issues such as perfusion or viability imaging of the myocardium, but in clinical routine of CAD diagnostics they play only a very limited role [40,41]. 4.3. Magnetic resonance imaging Cardiac magnetic resonance imaging (MRI) has its applications in the imaging of myocardial wall mobility (CINE-MRI) and myocardial perfusion (perfusion MRI) in combination with a pharmacological stress test (adenosine or dobutamine). In the context of risk stratification in acute chest pain, it is recommended primarily

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Table 3 Diagnostic pathways for patients with suspected ACS. Risk category

Strategy

ST elevation myocardial infarction (STEMI) Unstable high risk patients without ST elevation (NSTEMI) Stable high risk patients without ST elevation (NSTEMI) Intermediate risk patients

Immediate PCI

Low risk patients

Urgent PCI (<2 h) Early PCI (<72 h) Early PCI (<72 h) or non-invasive diagnostics Optional non-invasive diagnostics, discharge

in patients with intermediate cardiac risk and non-significant stress ECG [37,42,43]. A further MRI technique is the imaging of myocardial viability using delayed contrast enhancement (DCE-MRI). Its special field of application, however, is in viability diagnostics prior to planned revascularization. For primary CAD diagnostics it is less well suited [37,42]. MRI angiography of the coronary arteries is still under clinical development, and currently it does not play an important role in risk stratification in acute chest pain compared to the aforesaid techniques of cardiac imaging. 5. Invasive strategy Percutaneous coronary angiography as the gold standard of coronary imaging is the diagnostic method of choice in unstable patients in the context of acute chest pain, but as an invasive technique it requires certain clearly defined high risk criteria to be met [38]. The current recommendations relating to cardiac catheterization are listed in Table 3, the details in the following chapter. 6. Currently valid recommendations for action Subsequent diagnostic and therapeutic course of action depends on the results of the risk assessment based on the anamnestic, clinical, electrocardiographic and lab chemistry criteria described

above. Basically, for risk stratification both the individual prognostic factors listed above and risk scores are used. Most important among the scores listed in the guidelines of the American and European professional societies are the GRACE, TIMI and PURSUIT scores [36,44,45]. Based on these concepts, the cardiological societies have derived certain courses of action according to prognostic weighing with individually different recommendation regarding an invasive strategy. Even though there are minor differences between the individual guidelines, the recommendations relating to therapy of STEMI and unstable and stable high risk patients are almost uniform [8,10]. Fig. 1 shows a comprehensive algorithm for risk stratification of patients with undefined chest pain. 6.1. ST elevation myocardial infarction ST-segment elevation myocardial infarction (STEMI) accounts for some 5% of all coronary syndromes, but with a 30-day mortality of 30–50% they are associated with the highest risk. Thus, they must be treated by reperfusion therapy immediately [9,12,13]. The therapy of choice is coronary angiography followed by revascularization (PCI), provided onset of the complaints was less than 12 h before. The guidelines named above demonstrate superiority of PCI over thrombolysis even in case of delay due to transport of the patients into a cardiological center with intervention station, as long as such delay does not exceed 90 min. In hospitals without cardiac catheterization lab and presumably longer transfer time, thrombolysis is the only option for reperfusion therapy. However, according to the present data, thrombolysis therapy is significantly effective only during the first hours after onset of paint and basically limited by a number of specific contraindications [46]. 6.2. Unstable high risk patients without ST elevation Patients suspected of coronary syndrome who show no significant ST elevation or no (newly appeared) left bundle branch block, respectively, in the ECG are nevertheless considered as absolute high risk patients if they show clinically therapy-resistant angina pectoris symptoms, haemodynamic or respiratory instability or,

Fig. 1. Algorithm at the University Medical Center Mannheim for the management of patients with acute chest pain. Our cardiac CT protocol includes a non-enhanced calcium score scan prior to the contrast enhanced coronary CT angiography. A positive test result of this protocol is defined as a stenosis > 50% in the actual coronary CT angiography. A high calcium score without a significant stenosis does not necessarily lead to invasive PCA.

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in the ECG, life-threatening cardiac arrhythmia. For these patients there is an indication for urgent (within 2 h) cardiac catheterization [8,10]. 6.3. Stable high risk patients without ST elevation For patients with acute chest pain without ST elevation in the ECG who are haemodynamically and respiratorically stable but exhibit further defined high risk criteria, the professional societies recommend early (within 72 h) cardiac catheterization [8,10]. The high risk parameters mentioned include troponin level increase, significant ST-segment and T-wave changes, diabetes mellitus, leftventricular dysfunction, a current cardiac anamnesis (condition after myocardial infarction, CABG or PCI) as well as increased risk according to the risk scores mentioned above. 6.4. Intermediate risk patients A rather intermediate cardiac risk is found in patients who show certain risk factors but do not meet the high risk criteria mentioned above. As this group represents approximately 20–30% of all the patients in the chest pain units [2], over the recent years – also in view of newer (in particular non-invasive) diagnostic imaging test – it has received more and more attention. The discussion about the prognostic assessment of this patient group, however, has not been concluded yet, as intermediate riskpatients are assessed not quite consistently by the American and European professional societies. For determination of intermediate cardiac risk, on the one hand the score systems described above are recommended, on the other hand intermediate risk according to the current AHA/ACC guidelines is also defined by certain individual factors in combination with acute chest pain. These include non-cardiac arteriosclerotic conditions in the anamnesis, certain symptoms (successfully treated or nitrate-sensitive typical angina, recurrent angina), ECG changes (Q-waves in a plurality of leads, ST-segment depression < 1 mV), troponin in the intermediary range and more than 70 years of age [8]. Basically there is an agreement that such patients as do not meet any high risk criteria but do neither correspond unambiguously to the low risk definition will require extended technical diagnostics under monitoring conditions (optimally in a chest pain unit). In addition to serial troponin controls, for further risk evaluation there are several strategies available. Patients meeting the requirements for exercise ECG (potentially fit to be subjected to full exercise, ECG without bundle branch block or pacemaker rhythm) should primarily be examined by conventional ergometry. If these requirements are not met, there is – as described above – indication for pharmacological stress testing (adenosine or dobutamine) in combination with echocardiography, scintigraphy or magnetic resonance imaging. Alternatively, the current guidelines recommend – as described – cardiac CT including coronary calcification scoring and coronary CTA. If suspicion of coronary syndrome is corroborated during examination, further invasive examination by cardiac catheterization is indispensable [8]. 6.5. Low risk-patients Patients with undefined chest pain which meet, after completion of the risk stratification (risk factors and risk scores), the criteria neither of the high risk nor of the intermediate risk group, can be classified, according to the current recommendations, as elective and may be discharged without any further instrumental diagnostics, provided that over the course they are free of complaints and haemodynamically and respiratorically stable. Troponin and ECG must be serially without abnormal findings. Recommended terms for examination are, based on the temporal

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dynamics of troponin as described, at least 6 h after onset of the complaints, with the guidelines favouring, for reasons of safety, a control 6 h after admission [8,10]. First data relating to the dynamics of the sensitive troponin indicate that the terms for examination may in future possibly be shortened. However, meaningful longterm data are still missing here. 7. Differential diagnosis The potential differential diagnoses of the coronary syndrome must be considered early, in particular in patients with low cardiac risk. In practice this means that the diagnostic steps must at the same time address both relevant coronary and non-coronary risk factors. According to the aforesaid prognostic criteria, in particular pulmonary embolism, aortic dissection, non-coronary heart conditions and pneumothorax must be excluded. In case of increased d-dimers in combination with clinical signs of pulmonary embolism (cardinal symptoms: chest pain, dyspnoea and syncope) or aortic dissection (cardinal symptoms: chest pain and hypertension, indications of central or peripheral arterial occlusions), respectively, computed tomography of the thorax is the diagnostic method of choice. In patients for whom the coronary risk profile concomitantly provides an indication for coronary CTA, this can be done, if required, in an extended examination for triple rule-out [47–49]. Most non-coronary heart conditions can be diagnosed without major problems by echocardiography in combination with anamnesis, clinical examination and ECG. X-ray imaging of the thorax should be done routinely, not least for excluding a pneumothorax. Not infrequently, the cause of the complaints remains unexplained even after completion of the diagnostics. In such cases, the prime goal of emergency treatment is the exclusion of prognostically relevant conditions. In practice these patients are usually discharged from the emergency room or chest pain unit and integrated into outpatient facilities for subsequent elective diagnostics. 8. Conclusion Risk assessment of patients with undefined chest pain still remains a challenge for clinical practice in the emergency room. Problems include on the one hand reliable assessment of the high risk patient with or without myocardial infarction who must be recognized as such, monitored and, depending on his complaints and findings, possibly be subjected to reperfusion therapy quickly; on the other hand data also show that 2–5% of all cases of coronary syndrome are missed in the emergency room. This demonstrates that detection of low risk patients and reliable determination of their eligibility for discharge from the emergency room likewise pose major difficulties. International guidelines unanimously suggest risk stratification based on prognostic parameters, including anamnesis, clinical findings, 12-lead ECG, lab chemistry biomarkers and possibly extended radiological diagnostics. According to the current recommendations of these guidelines, certain risk groups may be defined together with the individually necessary courses of action for diagnosis and therapy, the latter comprising a wide spectrum of strategies (immediate reperfusion therapy, urgent or early cardiac catheterization, non-invasive diagnostics under monitoring conditions, clarification of eligibility for discharge). The differential diagnoses of the coronary syndrome must likewise be clarified or excluded, respectively, according to prognostic criteria. References [1] Nawar E, Niska R, Xu J. National Hospital ambulatory medical care survey: 2005 emergency department summary. Adv Data 2007;(386):1–32. [2] Ekelund U, Nilsson H, Frigyesi A, Torffvit O. Patients with suspected acute coronary syndrome in a university hospital emergency department: an observational study. BMC Emerg Med 2002;2(1):1.

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