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Acute Coronary Syndrome (ACS)

NICE guideline [NG185] Acute coronary syndromes. Published: 18 November 2020 This article covers the 3 subtypes of ACS - STEMI, NSTEMI, and unstable angina.

Background Information

ACS is the acute manifestation of coronary artery disease. This umbrella term includes the spectrum of STEMI, NSTEMI, and unstable angina.
 
 

Unstable angina 

NSTEMI

STEMI

Pathogenesis 

Partial occlusion → ischemia WIHTOUT infarction 

Partial occlusion → partial thickness (subendocardial) infarction 

Complete occlusion → full thickness (transmural) infarction 

ECG findings 

No ST elevation

Other ECG changes maybe present:

  • ST depression 
  • T wave abnormalities

ECG maybe normal 

ST elevation in at least 2 contiguous leads (see below for full criteria)

Cardiac troponin 

Troponin <99th centile 

Rise and fall 

  • Age 
  • Male 
  • Cardiovascular risk factors
  • Presence of other cardiovascular disease
  • Established coronary artery disease (e.g. previous MI, coronary revascularisation)

Chest pain / discomfort that often occurs at rest and is not relieved with rest or sublingual nitrates

  • May radiate to the neck, jaw, shoulders, or arms 
 

Other clinical features that often accompany chest pain:

  • Dyspnoea
  • Nausea and vomiting 
  • Diaphoresis 

ACS Management Guidelines

The following are recommended for all patients with suspected ACS: (ESC 2024 ACS guidelines)

  • Clinical history and examination
  • 1st line diagnostic tool: 12-lead ECG 
  • High-sensitivity cardiac troponin (hs-cTN)

MONA is a common acronym

  • M – Morphine (only if in severe pain)
  • O – Oxygen  (only if O2 saturation <94%)
  • N – Nitrate (should not be used in suspected right ventricular infarction) 
  • A – Aspirin 300mg

There are 2 management pathways - depending on whether it is STEMI or non-STEMI (i.e. NSTEMI and unstable angina):
  • STEMI pathway - 2 options
    • Reperfusion therapy (PCIPercutaneous coronary intervention / fibrinolysis)
    • Medical management
 
  • NSTEMI / unstable angina pathway - 2 options (depending on risk stratification)
    • PCIPercutaneous coronary intervention 
    • Medical management

NICE guidelines did not specify criteria for STEMI. Information from this section is as per ESC guidelines on ACS (2023).

New ST elevation at J point in ≥2 contiguous leads:
  • ST elevation in V2-V3
    • Men <40 y/o: ≥2.5mm
    • Men ≥40 y/o: ≥2.0mm
    • Women of any age: ≥1.5mm
  • AND/OR
  • Other leads: ≥1mm in the absence of LVHLeft ventricular hypertrophy / LBBBLeft bundle branch block

Initial management: aspirin 300mg 


Definitive management depends on eligibility for reperfusion therapy, that is determined by time from symptom onset - cut off is 12 hours. 

There are 2 options for reperfusion therapy:
  • Angiography +/- percutaneous coronary intervention (PCI) 
  • Fibrinolysis (medical) 


The choice is determined by whether there is access to cath lab within 120 min (2 hours). 

 

NICE guidelines also made the following recommendations regarding PCI:

  • Offer if symptoms onset <12 hours with acute STEMI + cardiogenic shock
  • Consider if onset >12 hours with evidence of MI
  • Consider if onset >12 hours but develops cardiogenic shock

Recommendations regarding angiography +/- PCI:

  • Drug-eluting stent preferred over bare metal stent, if stenting indicated 
  • Radial access preferred over femoral access

Adjuvant drug therapy:
  • Dual antiplatelet therapy 
    • 1st line: aspirin + prasugrel 
    • If patient already takes oral anticoagulant: aspirin + clopidogrel
 
  • Anti-thrombin therapy during PCI
    • Radical access: UFHUnfractionated heparin (also known as just heparin) + bailout GpIIb/IIIa inhibitor
    • Femoral access: bivalirudin + bailout GpIIb/IIIa inhibitor
 

Choice of drug is often not that straightforward. Influence by local guidelines and local availability.

NICE also recommend offering ticagrelor or clopidogrel as an alternative in people aged 75 and over, considering whether the risk of bleeding with prasugrel outweighs its benefit.


Offer all the following:

  • Fibrinolytic agent: tissue plasminogen activator (e.g. alteplase, streptokinase)
  • Anti-thrombin 
  • Dual antiplatelet therapy 
    • 1st line: aspirin + ticagrelor 
    • High bleeding risk: aspirin + clopidogrel OR aspirin monotherapy 
 

Then, offer ECG 60-90 minutes after:

  • If ST elevation still present on ECG → immediate angiography +/- PCI if indicated
  • Do not repeat fibrinolytic therapy

Dual antiplatelet therapy 

  • 1st line: aspirin + ticagrelor 
  • High bleeding risk: aspirin + clopidogrel OR aspirin monotherapy

Offer echocardiogram to assess left ventricular function in all patients who had a STEMI.

Initial management (both):
  • Aspirin 300mg 
  • Antithrombin therapy
    • 1st line: fondaparinux
    • If high bleeding risk / renal impairment (creatinine >265 mmol/L) / immediate angiography planned: UFHUnfractionated heparin (also known as heparin)

Definitive management depends on risk stratification with GRACE score (predicts 6-month mortality).

 

If the patient is clinically unstable → offer immediate PCI without taking GRACE score into account.

All of the following:
  • Angiography +/- PCI within 72 hours
  • UFHUnfractionated heparin (also known as heparin), even if fondaparinux has been given
  • Dual antiplatelet therapy
    • 1st line: aspirin + prasugrel / ticargrelor
    • Already taking oral anticoagulant: aspirin + clopidogrel
 

Recommendations regarding angiography +/- PCI:

  • Drug-eluting stent, if stenting indicated 
  • Radial access, preferred over femoral access

Medical management with dual antiplatelet therapy:
  • 1st line: aspirin + ticagrelor 
  • High bleeding risk: aspirin + clopidogrel OR aspirin monotherapy 
 

Only consider angiography +/- PCI if ischaemia testing is positive


  • Offer echocardiogram to assess left ventricular function
    • In all NSTEMI cases
    • Consider in unstable angina  
 
  • Consider ischaemia testing in those who have been medically managed without coronary angiography

No PCI (STEMI / NSTEMI / Unstable angina)

  • 1st line: aspirin + ticagrelor 
  • High bleeding risk: aspirin + clopidogrel OR aspirin monotherapy 
 

STEMI with PCI

  • 1st line: aspirin + prasugrel 
  • If taking oral anticoagulant: aspirin + clopidogrel 
 

NSTEMI / Unstable angina with PCI

  • 1st line: aspirin + prasugrel / ticagrelor 
  • If taking oral anticoagulant: aspirin + clopidogrel

ACS Secondary Prevention Guidelines

  • Cardiac rehabilitation program
  • Lifestyle advice
    • Mediterranean style diet
    • Regular physical activity
    • Smoking cessation
    • Advise on alcohol consumption
    • Weight management
    • Sexual activity can be resumed 4 weeks after 

NICE guideline recommendations regarding various supplements:
 

Omega-3 fatty acid 

Do not recommend

  • But if the person chooses to, there is no evidence of harm 

Beta-carotene 

Advise against 

Vitamin E/C/B9 (folic acid)

Do not recommend 

Offer ALL the following to ALL patients:
  • Dual antiplatelet therapy
    • Aspirin life-long (if aspirin not appropriate → clopidogrel)
    • 2nd antiplatelet agent for up to 12 months
  • High-intensity statin (e.g. atorvastatin 80mg) life-long
  • ACE inhibitor for life-long - start once hemodynamically stable
  • Beta blocker for 12 months if normal LVEF - start once hemodynamically stable

Add-on if presence of heart failure features and ↓ LVEF
  • Aldosterone antagonist (e.g. spironolactone) - initiate within 3-14 days of MI, preferably after starting ACE inhibitor

References

Author: Canada Edu 
Reviewer: TBC
Last Edited: 22/01/2025