Non-ST-elevation myocardial infarction

Last reviewed: June 2019

Last updated: December 2018

Summary

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, dyspnea, nausea, and/or anxiety. Women present more commonly with middle/upper back pain or dyspnea and similar associated symptoms.

Symptoms are indistinguishable from those of unstable angina. However, non-ST-elevation myocardial infarction (MI) is differentiated from unstable angina by a rise of troponin.

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-ischemic (beta-blockers, nitrates), anticoagulant (heparin), and dual antiplatelet agents (aspirin plus a P2Y12 receptor inhibitor) is needed. Higher-risk patients should be considered for an early invasive strategy (coronary angiography and revascularization in 12-24 hours).

Complications are progression or worsening of MI, heart failure, cardiogenic shock, arrhythmias, and death.

Definition

Non-ST-elevation myocardial infarction (NSTEMI) is an acute ischemic event causing myocyte necrosis. The initial ECG may show ischemic changes such as ST depressions, T-wave inversions, or transient ST elevations; however, it may also be normal or show nonspecific changes. If persistent ST elevation, evidence of posterior MI, 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 ischemic injury to the myocardium, which is detected by elevation of troponin. [1] It can be distinguished from unstable angina pectoris by normal serial troponin.

History and exam

Key diagnostic factors

chest pain
diaphoresis
recent percutaneous coronary intervention or previous coronary artery bypass graft

Full details

Other diagnostic factors

physical exertion
shortness of breath
weakness
anxiety
nausea
vomiting
abdominal pain
hypertension
cold exposure
emotional upset
early morning onset
syncope
hypotension
arrhythmias
abnormal heart sounds

Full details

Risk factors

atherosclerosis (history of angina, myocardial infarction, stroke, transient ischemic attack, peripheral vascular disease)
diabetes
smoking
dyslipidemia
family history of premature coronary artery disease (CAD)
age >65 years
hypertension
obesity and metabolic syndrome phenotype
physical inactivity
cocaine use
depression
stent thrombosis or restenosis
chronic kidney disease
surgical procedures (including intraoperative and postoperative periods)
sleep apnea

Full details

Diagnostic investigations

1st investigations to order

ECG
trial of sublingual nitroglycerin
cardiac troponins
creatine kinase (CK)
CK-MB (cardiac isoforms)
CBC
BUN and serum creatinine
electrolytes
liver function tests (LFTs)
blood glucose
chest x-ray

Full details

Investigations to consider

lipids
brain natriuretic peptide (BNP) or N-terminal pro-BNP (NT-pro-BNP)
echocardiography
angiography
stress testing
coronary CT angiography (CCTA)

Full details

Treatment algorithm

ACUTE

acute presentation

ONGOING

post-stabilization

Contributors

Authors VIEW ALL 

Cody S. Deen, MD

Assistant Professor of Medicine

Director of Cardiology

Hillsborough Hospital

University of North Carolina

Hillsborough

Disclosures

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.

Acknowledgements

Dr Cody S. Deen would like to gratefully acknowledge Dr Sripal Bangalore, Dr Mina Owlia, Dr Thomas Vanhecke, and Dr Dena Krishnan, the previous contributors to this topic.

Peer reviewers VIEW ALL 

Nicolas Palaskas, MD, FACC

Assistant Professor

University of Texas MD Anderson Cancer Center

Houston

Disclosures

NP declares that he has no competing interests.

Edward Ullman, MD

Associate Professor

Department of Emergency Medicine

Beth Israel Medical Deaconess Center

Boston

Disclosures

EU declares that he has no competing interests.

Deepak L. Bhatt, MD

Associate Professor of Medicine

Department of Cardiovascular Medicine

Cleveland Clinic

Disclosures

DLB declares that he has no competing interests.

Shrilla Banerjee, MBMD, MRCP

Consultant Cardiologist

East Surrey Hospital

Surrey and Sussex NHS Trust

Surrey

Disclosures

SB declares that she has no competing interests.

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Non-ST-elevation myocardial infarction

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

acute presentation

post-stabilization

Contributors

Authors VIEW ALL 

Cody S. Deen, MD

Disclosures

Acknowledgements

Peer reviewers VIEW ALL 

Nicolas Palaskas, MD, FACC

Disclosures

Edward Ullman, MD

Disclosures

Deepak L. Bhatt, MD

Disclosures

Shrilla Banerjee, MBMD, MRCP

Disclosures

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