Acute coronary syndrome (ACS) refers to a spectrum of acute myocardial ischemia and/or infarction. Classically ACS has been divided into three clinical categories according to the presence or absence of ST-segment elevation on the initial ECG, together with measurement of myocardial biomarkers, such as high-sensitivity cardiac troponins.[1] [2] In ST-elevation myocardial infarction (STEMI) the ECG shows persistent ST-segment elevation in two or more anatomically contiguous leads. Unstable angina and non-ST-elevation myocardial infarction (NSTEMI) represent a continuum of pathology, differing mainly by the presence of markers of myocardial damage in NSTEMI.[3] Therefore some guidelines have grouped unstable angina and NSTEMI as "non-ST-elevation acute coronary syndromes".[3]
Overview
Related Diseases & Conditions
Summary
Unstable angina (UA) is an acute coronary syndrome that is defined by the absence of biochemical evidence of myocardial damage.[4] UA is characterized by specific clinical findings of prolonged (>20 minutes) angina at rest; new onset of severe angina; angina that is increasing in frequency, longer in duration, or lower in threshold; or angina that occurs after a recent episode of myocardial infarction.[4] The ECG may be normal or may show ST-segment depression, transient ST-segment elevation, or T-wave inversion.[4] Cardiac biomarkers (high-sensitivity cardiac troponins) should be measured on presentation to rule out acute myocardial infarction; subsequent/serial measurements may be needed.[4] [5] The early management of patients with suspected UA is focused on initial interventions and triage according to the presumptive diagnosis.Summary
Non-ST-elevation myocardial infarction (NSTEMI) is an acute ischemic event causing myocyte necrosis. The initial ECG may show ischemic changes such as ST depression, T-wave changes, or transient ST elevation; however, ECG may also be normal or show non-specific changes. The distinction from unstable angina (UA) is based on cardiac biomarkers; high-sensitivity cardiac troponins are elevated (>99th percentile of normal) at presentation or after several hours in NSTEMI.[3] Treatment is directed toward relief of ischemia, prevention of further thrombosis or embolism, and stabilization of hemodynamic status, followed by early risk stratification for further treatment.Summary
ST-elevation myocardial infarction (STEMI) is suspected when a patient presents with persistent ST-segment elevation in two or more anatomically contiguous ECG leads in the context of a consistent clinical history.[1] Cardiac biomarkers (troponins) are elevated. Treatment should, however, be started immediately in patients with a typical history and ECG changes, without waiting for laboratory results. Immediate and prompt reperfusion can prevent or minimize myocardial damage and improve the chances of survival and recovery.[6]
Citations
1. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). J Am Coll Cardiol. 2018 Oct 30;72(18):2231-64.[Abstract][Full Text]
2. National Institute for Health and Care Excellence. Acute coronary syndromes. Nov 2020 [internet publication].[Full Text]
3. Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;130:e344-426.[Abstract][Full Text]
4. Collet JP, Thiele H, Barbato E, et al. 2020 ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Eur Heart J. 2021 Apr 7;42(14):1289-1367.[Abstract][Full Text]
5. Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guideline for the evaluation and diagnosis of chest pain: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. J Am Coll Cardiol. 2021 Nov 30;78(22):e187-285.[Abstract][Full Text]
6. Lawton JS, Tamis-Holland JE, Bangalore S, et al. 2021 ACC/AHA/SCAI guideline for coronary artery revascularization: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022 Jan 18;145(3):e18-114.[Abstract][Full Text]
