In late August 2020, the European Society of Cardiology (ESC) released their updated guidelines for the diagnosis and management of non ST-elevation (NSTE) acute coronary syndrome (ACS).[1,2] The updates place increased reliance on high-sensitivity cardiac troponin testing (hs-cTn) for diagnosis, embrace coronary computed tomography (CT) imaging to rule out lower-risk patients, as well as highlight the need for personalized antiplatelet regimens, systems of care, and quality improvement. Key messages are below.
Chest discomfort without persistent ST-segment elevation (NSTE-ACS) is the main symptom that initiates the diagnostic and therapeutic chain. The myocardial pathology consists of cardiomyocyte necrosis, measured by troponin release, or, less often, myocardial ischemia without cell damage (unstable angina). Those with unstable angina have a much lower death risk and benefit less from an aggressive pharmacologic and invasive approach.
Troponin assays and other biomarkers
The ESC recommends hs-cTn assays over less sensitive assays (higher diagnostic accuracy, same low cost). Note that many cardiac conditions other than myocardial infarction (MI) also result in cardiomyocyte injury and can raise cTn levels.
Biomarkers such as creatine kinase myocardial band (CK-MB) and copeptin may be clinically relevant in specific circumstances when used with non hs-cTn T or I (T/I). There is a more rapid post-MI reduction of CK-MB, and it may have an added value for detecting early reinfarction. Routine use of copeptin is recommended as an additional biomarker for the early exclusion of MI in the infrequent setting of unavailable hs-cTn assays.
Rapid “rule-in” and “rule-out” algorithms
Use of hs-cTn assays (higher sensitivity, diagnostic accuracy) can shorten the time interval to the second cTn assessment for detecting MI at presentation. Recommendations include using the 0 h/1h algorithm (best option, blood draw at 0 h and 1 h) or the 0 h/2h algorithm (second-best option, blood draw at 0 h and 2 h). Use of the 0 h/1h and 0 h/2h algorithms with clinical and electrocardiographic (ECG) findings aid in identifying appropriate candidates for early discharge and outpatient management.
Four clinical variables affect hs-cTn levels besides the presence/absence of MI, as follows:
Age: Up to 300% differences in concentration between healthy very young versus “healthy” very old individuals
Renal dysfunction: Up to 300% differences in concentration between otherwise healthy patients with very high versus very low estimated glomerular filtration rate (eGFR)
Chest pain onset: Over 300%
Sex: About 40%
Ischemic and bleeding risk assessments
Initial cTn levels add prognostic information about short- and long-term mortality to clinical and ECG variables (higher hs-cTn levels raise mortality risk). Measure serum creatinine and eGFR in all patients with NSTE-ACS; they are prognostic factors and key elements of the Global Registry of Acute Coronary Events (GRACE) risk score (superior assessment to subjective physician assessment for the occurrence of death or MI). Natriuretic peptides may add incremental prognostic information and may aid in risk stratification.
Academic Research Consortium for High Bleeding Risk (ARC-HBR) is a pragmatic approach for evaluating bleeding risk (includes the most recent trials of HBR patients previously excluded from clinical trials of dual antiplatelet therapy [DAPT] duration or intensity). The PRECISE-DAPT (PREdicting bleeding Complications In patients undergoing Stent implantation and subsEquent DAPT) score may be used to guide and inform decision making on DAPT duration with a modest predictive value for major bleeding. Their value in improving patient outcomes remains unclear.
After MI has been excluded, elective noninvasive/invasive imaging may still be indicated based on clinical assessment. Coronary CT angiography (CCTA) may be an option in those with a low-to-modest clinical likelihood of unstable angina as a normal scan excludes coronary artery disease (CAD): It has a high negative predictive value (NPV) to rule out ACS (by excluding CAD) and a positive outcome in patients presenting to the emergency department with a low-to-intermediate pretest probability for ACS and a normal CCTA. Upfront imaging with CCTA also reduces the need for invasive coronary angiography (ICA) in high-risk patients. Other imaging options based on risk evaluation include stress imaging by cardiac magnetic resonance imaging (CMRI), stress echocardiography, or nuclear imaging.
Risk Stratification for an Invasive Approach
The ESC recommends an early routine invasive approach within 24 hours of admission for NSTEMI (based on hs-cTn levels, GRACE risk score >140, and dynamic new/presumably new ST-segment changes) to improve major adverse cardiac events and possibly early survival. Highly unstable patients require immediate invasive angiography based on hemodynamic status, arrythmias, acute heart failure, or persistent chest pain. For all other clinical presentations, a selective invasive approach may be performed based on noninvasive testing or clinical risk assessment.
The main technical aspects of percutaneous coronary intervention (PCI) in NSTE-ACS patients do not differ from the invasive assessment and revascularization strategies for other manifestations of CAD. Radial access is the recommended and preferred approach in NSTE-ACS patients undergoing invasive assessment with or without PCI. As NSTE-ACS commonly involves multivessel disease, base the determination of revascularization timing and completeness on the functional relevance of all stenoses, patient age and comorbidities, general clinical condition, and left ventricular function.
MI With Nonobstructive Coronary Arteries (MINOCA)
MINOCA comprises a heterogeneous group of underlying causes potentially involving both coronary and noncoronary pathologic conditions, with the latter including cardiac and extra-cardiac disorders. By consensus, myocarditis and Takotsubo syndrome are excluded. CMRI, a key diagnostic tool, identifies the underlying cause in over 85% of patients and the subsequent appropriate treatment.
Spontaneous Coronary Artery Dissection
Spontaneous coronary artery dissection is a nonatherosclerotic, nontraumatic, or iatrogenic separation of the coronary arterial tunics due to vasa vasorum hemorrhage or intimal tear. It comprises up to 4% of all ACS but has a higher reported incidence (22-35% of ACS) in women younger than age 60 years. Intracoronary imaging is very useful for the diagnosis and treatment strategy. Medical treatment remains to be established.
Pretreatment With P2Y12 Receptor Inhibitors
Due to a lack of established benefit, the ESC does not recommend routine pretreatment with a P2Y12 receptor inhibitor in NSTE-ACS patients with unknown coronary anatomy and a planned early invasive management. However, it may be considered in selected cases and based on the patient’s bleeding risk.
Barring contraindications, DAPT consisting of a 12-month regimen of a potent P2Y12 receptor inhibitor plus aspirin is generally recommended, regardless of the stent type. DAPT duration can be shortened (<12 months), extended (>12 months), or modified by switching DAPT or de-escalation, based on individual clinical judgment according to the patient’s ischemic and bleeding risks, the occurrence of adverse events, comorbidities, co-medications, and the availability of the respective drugs.
Triple Antithrombotic Therapy (TAT)
In at least 6-8% of patients undergoing PCI, long-term oral anticoagulation is indicated and should be continued. For eligible patients, non-vitamin K antagonist oral anticoagulants (NOACs) are preferred over vitamin K antagonists (VKAs). The ESC recommends dual antithrombotic therapy (DAT) with a NOAC for stroke prevention and single antiplatelet therapy (SAPT) (clopidogrel is preferred) as the default strategy up to 12 months after a short period up to 1 week of TAT (NOAC + DAPT). TAT may be prolonged up to 1 month when the ischemic risk outweighs the bleeding risk.
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Cite this: Acute Coronary Syndromes Clinical Practice Guidelines (ESC, 2020) - Medscape - Sep 30, 2020.