Non-ST-elevation myocardial infarction (NSTEMI) is part of the acute coronary syndrome spectrum. Usually caused by a partial or near-complete occlusion of a coronary artery resulting in compromised blood flow to myocardium with subsequent myocardial injury or infarction as demonstrated by elevation in troponin.
There are differences in typical presentation between the sexes. Male patients typically present with chest pressure/discomfort lasting at least several minutes, at times accompanied by sweating, dyspnoea, nausea, and/or anxiety. Women present more commonly with middle/upper back pain or dyspnoea and similar associated symptoms.
NSTEMI is differentiated from unstable angina by a dynamic elevation of troponin above the 99th percentile. A patient with NSTEMI may also be clinically unstable (e.g., low blood pressure, shock, left ventricular failure) which is not a feature of unstable angina.
ECG is the first-line investigation in all patients and should not be delayed for history, examination, or other tests.
Early risk stratification and treatment with anti-ischaemic (beta-blockers, nitrates), anticoagulant (heparin), and dual antiplatelet agents (aspirin plus a P2Y12 receptor inhibitor) is needed. Higher-risk patients (those with ‘intermediate’, ‘high’, or ‘highest’ risk of future adverse cardiac events based on risk assessment) should be considered for an early invasive strategy (coronary angiography and revascularisation within 72 hours).
Complications are progression or worsening of myocardial infarction; heart failure, cardiogenic shock, arrhythmias, and death.
Non-ST-elevation myocardial infarction (NSTEMI) is an acute ischaemic event causing myocyte necrosis. The initial ECG may show ischaemic changes such as ST depression, T-wave changes, or transient ST elevation; however, it may also be normal or show non-specific changes. If persistent ST elevation, evidence of posterior myocardial infarction, or a new left bundle-branch block is present, then the patient should be evaluated as an ST-elevation myocardial infarction. NSTEMI, therefore, encompasses a broad spectrum of ischaemic injury to the myocardium, which is detected by elevation of troponin. It can be distinguished from unstable angina pectoris by normal serial troponin.
History and exam
Key diagnostic factors
- chest pain
- risk factors for cardiovascular disease
- marked sweating
- cardiogenic shock
- acute heart failure
Other diagnostic factors
- nausea and vomiting
- heart murmur
- epigastric pain
- back pain
- atherosclerosis (history of angina, myocardial infarction, stroke, transient ischaemic attack, peripheral vascular disease)
- family history of premature coronary artery disease (CAD)
- age >65 years
- obesity and metabolic syndrome phenotype
- physical inactivity
- cocaine use
- stent thrombosis or restenosis
- chronic kidney disease
- surgical procedures (including intra-operative and postoperative periods)
- sleep apnoea
1st investigations to order
- high-sensitivity troponin
- chest x-ray
- full blood count
- urea, electrolytes, and creatinine
- liver function tests
- blood glucose
- C-reactive protein
Investigations to consider
- invasive coronary angiography (ICA)
clinically unstable (suspected or confirmed NSTEMI)
clinically stable (suspected or confirmed NSTEMI)
Resham Baruah, MBBS, BSc MRCP, PhD
Chelsea and Westminster Hospital NHS Foundation Trust
Royal Brompton & Harefield NHS Foundation Trust
RB is specialist advisor to the 2018 NICE guideline on chronic heart failure in adults and is a member of the European Heart Failure Association Task Force on palliative care in heart failure.
RB has received honoraria/speakers’ fees from Novartis and Boehringer Ingelheim.
Adam Hartley, MBBS, BSc, MRCP
Wellcome Trust Clinical Research Fellow
Imperial College London
Specialist Registrar in Cardiology
Imperial College Healthcare NHS Trust
AH declares that he has no competing interests.
BMJ Best Practice would like to gratefully acknowledge the previous expert contributor, whose work has been retained in parts of the content:
Cody S Deen, MD
Assistant Professor of Medicine
Director of Cardiology
University of North Carolina
CSD was previously the Director of Cardiac Rehab for Chatham Hospital, which was financially set up as a consultancy relationship, until 2017. CSD has spoken (unpaid) at the Update in Cardiology and Update in Internal Medicine Conferences at UNC for the last 5 years. CSD has served as the PI for the Dal-GeneE (site now closed) and the ACCELERATE Trials at the University of North Carolina (trial now completed). Each trial required paid travel to an investigator meeting.
Gavin Galasko, BM, BCh, MA, DM (Oxon), FRCP
Consultant Interventional Cardiologist
Director of Research, Development and Innovation
Blackpool Teaching Hospitals NHS Foundation Trust
GG declares that he has no competing interests.
Section Editor, BMJ Best Practice
AS declares that she has no competing interests.
Lead Section Editor, BMJ Best Practice
SM works as a freelance medical journalist and editor, video editorial director and presenter, and communications trainer. In this capacity, she has been paid, and continues to be paid, by a wide range of organisations for providing these skills on a professional basis. These include: NHS organisations, including the National Institute for Health and Care Excellence, NHS Choices, NHS Kidney Care, and others; publishers and medical education companies, including the BMJ Group, the Lancet group, Medscape, and others; professional organisations, including the British Thoracic Oncology Group, the European Society for Medical Oncology, the National Confidential Enquiry into Patient Outcome and Death, and others; charities and patients’ organisations, including the Roy Castle Lung Cancer Foundation and others; pharmaceutical companies, including Bayer, Boehringer Ingelheim, Novartis, and others; and communications agencies, including Publicis, Red Healthcare and others. She has no stock options or shares in any pharmaceutical or healthcare companies; however, she invests in a personal pension, which may invest in these types of companies. She is managing director of Susan Mayor Limited, the company name under which she provides medical writing and communications services.
Lead Section Editor, BMJ Best Practice
RW declares that she has no competing interests.
Comorbidities Editor, BMJ Best Practice
JC declares that she has no competing interests.
Drug Editor, BMJ Best Practice
AM declares that he has no competing interests.
- ST-elevation myocardial infarction
- Unstable angina
- Aortic dissection
- Acute coronary syndromes
- ESC guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation
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