Non ST-Elevation Myocardial Infarction


Chest pain. Central, crushing, radiation to arm, neck or jaw. Lasting >20 mins
Dyspnoea and palpitations also common
Beware abnormal presentations, especially in the elderly or diabetics with 'silent' infarct - epigastric pain, pulmonary oedema, acute confusion

Symptoms of NSTEMI overlap with STEMI. NSTEMI patients tend to be older and have more co-morbidities


Features of pain - SOCRATES - sight, onset, character, radiation, associated features (autonomic features), time course, exacerbating/relieving factors (breathing, position, exertion, eating) and severity (0-10)
Recent trauma?
Does the patient have a GTN spray and has it helped their symptoms? - relief may occur unlike STEMI
Does the patient have any risk factors for developing vascular disease - Hypertension, hypercholesterolaemia, obesity, diabetes, previous acute coronary event/stroke, smoker, lifestyle/occupation, family history of ischaemic heart disease?
PMHx - consider other causes for the presenting symptoms, such as gastric, respiratory problems, MSK
Medications - cardiac or respiratory medications, antacids, anticoagulants

Vital signs / observations

Hypotensive/ hypertensive


'clammy' - cool and sweaty, pallor
Signs of heart failure? - raised JVP, basal crepitations, 3rd heart sound
Added heart sounds - pan systolic murmer may suggest rupture/dysfunction of papillary muscle/VSD

Bedside tests

ECG - ST depression, inverted or flat T waves; subsequent evolution of changes + T wave inversion. Non-specific changes. ECG may be normal

Laboratory investigations

FBC, U&E, LFT, lipids, glucose, lactate
Cardiac Markers - various cardiac markers so check locally which you should send at what time-points after the onset of chest pain. Troponin I or T will show an increase 6 hour post-pain and remain raised for up to 14 days. Typically blood test taken on presentation and 12h after worst pain.
cardiac markers useful for NSTEMI as will help differentiate from unstable angina
Treatment should Not be withheld waiting on results as ECG findings and history alone are sufficient to make the diagnosis
Consider ABG if patient acutely unwell

Radiological investigations

CXR - cardiomegaly, signs of LV failure (pulmonary oedema)
Urgent echo/CT if suspect other pathologies such as PE, Aortic dissection etc


Immediate management

Continually monitor pulse oximeter, BP and ECG
Morphine - eg IV Diamorphine 2.5-5mg + Antiemetic
Oxygen - only if SpO2 shows evidence of hypoxaemia
Nitratrates - GTN 400micrograms SL, 2 puffs SL every 5 minutes until pain free
Aspirin 300mg PO STAT
Clopidogrel 300mg PO

Anticoagulate with LMWH (Fondaparinux)
Beta Blockers Bisoprolol 10mg STAT, Metoprolol 50-100mg/8 hours but beware in patients with COPD, hypotension and LVF
IV Nitrate if pain continues

Risk Stratification

High Risk Patients Low Risk Patients
Clinical Features Persistent or recurrent ischaemia, ST depression, diabetes, raised troponin No further pain, flat or inverted T waves or normal ECG and negative troponin
Management CCU bed, consider for Glycoprotein IIb/IIIa inhibitors (e.g. Tirofiban) and urgent catheterisation Ensure pain free and arrange further tests such as exercise ECG, angiogram. Discharge home

Prior to discharge

Wean of GTN infusion when established on oral medication
Stop heparin when pain free for 24 hours, but give at least 3-5 days of therapy

Aim to reduce modifiable risk factors such as smoking, obesity, control of diabetes, blood pressure and cholesterol.


Smoking cessation and referral to cardiac rehabilitation to provide support for lifestyle modifications such as diet and re-introduction of physical activity following MI


ACE inhibitor - eg ramipril. Start on low dose for example Ramipril 2.5mg daily, then increase to either 5mg then maximally 10mg

Statin, eg atorvastatin 10-80mg PO ON

Beta blocker, eg bisoprolol 5mg PO OD (this can be uptitrated as BP allows)

Aspirin - 75mg OD for life

Clopidogrel - 75mg OD for 12 months for patients who have had an NSTEMI regardless of treatment

Symptomatic treatment with nitrates (GTN) and possible addition of calcium channel blockers etc

Wean of GTN infusion when established on oral medication
Stop heparin when pain free for 24 hours, but give at least 3-5 days of therapy

Follow up

Review in out-patient clinic and through cardiac rehabilitation


Complications are less common for NSTEMI than STEMI


Cardiac Arrest
Systemic Embolism
Valvular Pathology


Late malignant ventricular arrhythmias
Dreslers Syndrome (Recurrent pericarditis, pleural effusion, fever)
Left Ventricular Aneurysm


Overall risk of Death 1-3% but 15% for refractory angina despite medical therapy. Risk Stratification will help predict mortality. Factors increasing mortality include:

  • History of unstable angina
  • ST depression or widespread T-wave inversion
  • Raised troponin
  • Age >70 years
  • General comorbidity
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