Acute chest pain

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Quick Overview

Acute chest pain is a high-stakes emergency presentation requiring rapid risk stratification to identify life-threatening causes (ACS, aortic dissection, PE). NICE NG185 emphasizes troponin timing, validated risk scores (HEART, GRACE), and immediate ECG interpretation to guide management pathways and reduce unnecessary admissions.

Core Facts & Concepts

Troponin Interpretation & Timing

  • High-sensitivity troponin (hs-Tn): Baseline + repeat at 3 hours (NICE NG185)
  • Rule-out threshold: <5 ng/L at presentation (if pain >6h) + non-ischemic ECG
  • Rule-in threshold: >52 ng/L (99th percentile varies by assay)
  • Delta change: ≥20% rise/fall suggests acute MI vs chronic elevation

Figure 1: ECG showing ST elevation in anterior leads V1-V4

STEMI vs NSTEMI Management

FeatureSTEMINSTEMI
ECGST elevation ≥1mm (≥2mm V2-V3) or new LBBBST depression, T-wave inversion, or normal
Reperfusion targetPrimary PCI <120 min (symptom onset)Risk-stratified: PCI <72h if high-risk
Immediate RxAspirin 300mg + Ticagrelor 180mg + morphine + GTNAspirin 300mg + Fondaparinux 2.5mg
TroponinUsually elevated but don't wait for resultEssential for diagnosis + risk stratification

Risk Scores

  • GRACE score (NICE preferred): Predicts 6-month mortality; >140 = high-risk (invasive strategy <72h)
  • HEART score: 0-3 = discharge safe; ≥4 = admit for observation/troponin

🚩 Aortic Dissection Red Flags

  • Tearing/ripping chest/back pain radiating to interscapular region
  • BP differential >20mmHg between arms
  • Pulse deficits, new aortic regurgitation murmur
  • Widened mediastinum on CXR (>8cm)
  • Investigation: CT aortogram (not troponin)

Problem-Solving Approach

Immediate Assessment (First 10 minutes)

  1. 12-lead ECG within 10 minutes of arrival
  2. ABCDE approach: O₂ if SpO₂ <94%, IV access, cardiac monitoring
  3. High-risk features screen: STEMI, haemodynamic instability, arrhythmia
  4. Aspirin 300mg immediately unless clear contraindication

Figure 2: Chest X-ray showing widened mediastinum

Risk Stratification Pathway (NICE NG185)

  1. STEMI identified: Activate primary PCI pathway (door-to-balloon <90 min if presenting hospital)
  2. Non-STEMI pathway:
    • Baseline troponin + repeat at 3h
    • Calculate GRACE score while awaiting troponin
    • High-risk (GRACE >140, ongoing pain, haemodynamic instability): Fondaparinux + invasive strategy <72h
    • Low-risk (GRACE <109, negative troponins): Consider discharge with outpatient follow-up

🚩 When to Suspect Non-ACS Causes

  • PE: Pleuritic pain, dyspnoea, risk factors (use Wells score)
  • Dissection: Sudden-onset tearing pain, BP asymmetry, neurological signs
  • Pericarditis: Positional pain (worse lying flat), PR depression on ECG, pericardial rub

Analysis Framework

Discriminating Features: ACS vs Mimics

CausePain CharacterECGTroponinKey Discriminator
STEMICentral crushing, radiationST elevation ≥1mmElevatedTime-critical: <12h symptom onset
NSTEMISimilar to STEMIST depression/T inversionElevated (3h repeat)GRACE score guides timing
Unstable anginaCrescendo patternMay be normalNormalClinical diagnosis if troponin negative
Aortic dissectionSudden tearing, back painUsually normalNormal (unless coronary involvement)CT aortogram diagnostic
PEPleuritic, worse inspirationSinus tachycardia, S1Q3T3May be mildly elevatedD-dimer + CTPA
PericarditisSharp, positional reliefWidespread ST elevation + PR depressionNormal/mildly elevatedPericardial rub, worse lying flat

⚠️ Warning: Troponin elevation ≠ ACS. Consider PE, myocarditis, renal failure, sepsis, takotsubo in context.

Visual Aid

HEART Score Components

ComponentPoints
HistoryHighly suspicious=2, Moderately=1, Slightly=0
ECGST deviation=2, Non-specific repolarization=1, Normal=0
Age≥65y=2, 45-64y=1, <45y=0
Risk factors≥3 factors=2, 1-2 factors=1, None=0
Troponin≥3x normal=2, 1-3x normal=1, Normal=0

Key Points Summary

ECG within 10 minutes is non-negotiable; STEMI diagnosis triggers immediate dual antiplatelet (aspirin 300mg + ticagrelor 180mg) + primary PCI pathway

High-sensitivity troponin protocol: Baseline + 3-hour repeat per NICE NG185; <5 ng/L rules out MI if pain >6h and ECG non-ischemic

GRACE score >140 = high-risk NSTEMI requiring invasive coronary angiography within 72 hours; <109 = low-risk suitable for early discharge

Aortic dissection red flags: Tearing pain, BP differential >20mmHg between arms, widened mediastinum on CXR → urgent CT aortogram (troponin misleads)

Don't anchor on troponin: Elevation occurs in PE, myocarditis, sepsis, renal failure; interpret with clinical context and ECG

HEART score 0-3 safely identifies patients for discharge without admission; ≥4 requires observation and serial troponins

📌 Remember: STEMI TIME - S=Symptoms <12h, T=Troponin don't wait, E=ECG <10 min, M=Morphine + antiemetic, I=Immediate dual antiplatelet, T=Transfer for PCI, I=IV access, M=Monitor continuously, E=Exclude dissection if atypical

Practice Questions: Acute chest pain

Test your understanding with these related questions

A 55-year-old man presents with acute severe abdominal pain and hypotension. He takes warfarin for atrial fibrillation. CT shows large retroperitoneal hematoma. His INR is 7.5. What is the most appropriate immediate management?

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Flashcards: Acute chest pain

1/10

_____ should be given in addition to dual antiplatelet therapy in NSTEMI patients who are not at a high risk of bleeding/ having angiography immediately

TAP TO REVEAL ANSWER

_____ should be given in addition to dual antiplatelet therapy in NSTEMI patients who are not at a high risk of bleeding/ having angiography immediately

Fondaparinux

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