Volume 3, Issue 4 - Special Issue: Update on the management of acute coronary syndrome / Guest Editors: Evangelos Giannitsis and Hugo A. Katus

The current version of the Universal Definition of Myocardial Infarction (MI) was published in 2012. An acute myocardial infarction (AMI) is characterized by evidence of myocardial necrosis in a clinical setting of acute myocardial ischemia. Diagnostic criteria include a rise and/or fall of serially tested cardiac biomarkers (preferentially cardiac troponins) with at least one value above the 99th percentile of the upper reference limit combined with symptoms of ischemia, new changes on electrocardiogram (ECG), imaging evidence of a new loss of viable myocardium or new regional wall motion abnormalities or the identification of an intracoronary thrombus by angiography or autopsy. Compared to previous versions, the current definition of MI includes minor modifications regarding ECG criteria and subtypes of MI as well as the use of cardiac imaging and high sensitivity troponin assays. This article summarizes the Universal MI definition and includes recommendations from the current guidelines for the management of patients with acute coronary syndrome. Strategies for “early rule-in” and “rule-out” of non-ST-elevation MI with high sensitivity cardiac troponin assays, risk scores for assessment of ischemic and bleeding risk and criteria for optimal timing of angiography are presented.

This article describes the role of cardiovascular magnetic resonance (CMR) and cardiac computed tomography (CCT) in the diagnostic work-up of patients with suspected acute coronary syndrome (ACS). Recent studies on the principles, diagnostic targets, clinical utility, accuracy, prognostic relevance and implications for clinical decision-making are discussed and current state-of-the-art and novel approaches are presented. The authors recognize that in ACS, time is of the essence and therefore put a special emphasis on the feasibility of tomographic cardiac imaging in realistic clinical settings.

Primary percutaneous intervention (PPCI) is the preferred treatment in patients with ST elevation myocardial infarction (STEMI) if this can be performed in a timely manner. The 2012 ESC Guidelines on management of AMI in patients presenting with ST-segment elevation advice that PPCI should be performed within 120 min of first medical contact. Prehospital diagnosis of patients with STEMI is performed to save time and make PPCI available to the majority of patients. Although diagnosing patients with STEMI is usually easy, there are important pitfalls and patients with STEMI are missed on occasion. In addition, it is well know that patients without ST elevation may also have a high-risk cardiac condition. The 2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation stress the importance of urgent CAG in patients with high-risk non ST-segment elevation myocardial infarction (NSTEMI). Unfortunately, these patients are difficult to diagnose in the acute phase and important time may be spend establishing the correct diagnosis. Prehospital biomarker measurement has emerged as a method to gain important additional information. We review the evidence on prehospital diagnosis of patients with STEMI and, In addition, we present the current knowledge on the new diagnostic methods that could have a future role in prehospital rule-in and rule-out of cardiac disease.

Security standards of our times largely exclude a discharge of patients with chest pain from the emergency departments (EDs) based on clinical assessment alone. Given the increasing use and consequently crowding of EDs worldwide and the large proportion of patients who present to the EDs with, however vague, signs and symptoms of acute coronary syndrome, there is a strong clinical and public health need to achieve a faster but safe rule-in and rule-out of acute myocardial infarction (AMI) to direct patients onto the correct management pathway. A number of approaches for a faster rule-in and rule-out of AMI are currently under research and evaluation and some have already been integrated into current guidelines and/or implemented into the clinical routine in selected centers. This article summarizes these different diagnostic strategies for patients with suspected AMI, using cardiac troponin alone or in combination with copeptin.

According to the universal definition, a diagnosis of acute myocardial infarction (AMI) can be made in the presence of a kinetic change of cardiac troponin (cTn) with at least one value above the 99th percentile of a healthy population together with clinical signs of myocardial ischemia. Thus, differences in 99th percentile cut-off values may have important diagnostic and therapeutic consequences for the correct AMI diagnosis. Following the introduction of high-sensitivity (hs) cTn assays with the ability to detect cTn in virtually every healthy individual, almost all available hs Tn assays suggest to use solitary 99th percentile cut-offs. However, several findings have questioned the use of a solitary cut-off for AMI diagnosis, as apparent age- and gender-dependent differences were found concerning the 99th percentile cut-off value. Moreover, there is an increasing number of studies which suggest a relevant diagnostic and prognostic benefit, when age- or gender-specific cut-offs values are used in comparison to general cut-offs. In contrast, other studies observed only a small impact on diagnostic reclassification and risk stratification. Given these ambiguous findings, there is currently no clear evidence for the use of age- and/or gender-dependent 99th percentiles. This review gives an overview of the rationale for gender- and age-dependent differences in cTn biomarker findings and discusses the implementation of these findings into clinical practice.

microRNAs are promising biomarkers for diverse cardiovascular diseases. While quantification of the small non-coding RNAs is routinely performed in the research laboratory, clinical-grade assessment of microRNAs in central laboratory environments or point-of-care testing is still in its infancy. In this review, we provide an overview on microRNAs as biomarkers for acute coronary syndromes and highlight promising technical approaches for microRNA-based assays systems.

High sensitive cardiac troponin assays have become the gold standard in the diagnosis of an acute type 1 myocardial infarction (MI) in the absence of ST-segment elevation. Several acute or chronic conditions that impact cardiac troponin levels in the absence of a MI might lead to a misdiagnosis of MI. For example, patients with impaired renal function as well as elderly patients often present with chronically increased cardiac troponin levels. Therefore, the diagnosis of MI type 1 based on the 99th percentile upper limit of normal threshold is more difficult in these patients. Different diagnostic approaches might help to overcome this limitation of reduced MI specificity of sensitive troponin assays. First, serial troponin measurement helps to differentiate chronic from acute troponin elevations. Second, specific diagnostic cut-offs, optimized for a particular patient group, like elderly patients, are able to regain specificity. Such an individualized use and interpretation of sensitive cardiac troponin measurements improves diagnostic accuracy and reduces the amount of misdiagnosed MI type 1.