Rule Out the Killers First, Diagnose Later
"The emergency approach to chest pain inverts the usual diagnostic order. You do not start with the most likely cause and work down; you start with the most lethal and work to exclude it. The goal in the first ten minutes is not a diagnosis — it is the confident exclusion of the six conditions that will kill this patient today. Most chest pain is benign, but the cost of missing the dangerous minority is measured in lives and lawsuits."
Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9th Ed. Chest Pain. McGraw-Hill; 2020.The six immediately life-threatening causes
1 · Acute coronary syndrome
STEMI/NSTEMI/unstable angina. ECG within 10 min; serial hs-troponin. Commonest lethal cause.
2 · Aortic dissection
Tearing pain to the back, pulse/BP differential, wide mediastinum. CT aortogram. Do not anticoagulate.
3 · Pulmonary embolism
Pleuritic pain, dyspnoea, hypoxia, tachycardia; risk factors. Wells/PERC → D-dimer or CTPA.
4 · Tension pneumothorax
Sudden pleuritic pain, dyspnoea, absent breath sounds, deviated trachea, shock. Clinical Dx → decompress.
5 · Cardiac tamponade
Beck's triad, pulsus paradoxus, low-voltage ECG. Echo → pericardiocentesis.
6 · Oesophageal rupture (Boerhaave)
Vomiting then severe pain, subcutaneous emphysema, mediastinitis. CT with oral contrast; high mortality.
Women, the elderly, and people with diabetes frequently present with ACS without classic crushing pain — dyspnoea, fatigue, epigastric discomfort, nausea, syncope. A normal initial ECG and a single normal troponin do not exclude ACS. "Indigestion" relieved by antacids, or pain reproduced partly on palpation, still allows a myocardial infarction — never let a benign-sounding feature close the case prematurely.
Pre-test Probability & the Troponin
"Chest-pain decision-making is applied Bayesian reasoning. The history sets the pre-test probability; the ECG and troponin move it up or down. A high-sensitivity troponin is exquisitely sensitive but not specific — it detects myocardial injury, not its cause. Interpreting a single value without the trajectory, the timing and the clinical context is how both missed infarcts and needless admissions are made."
Rosen's Emergency Medicine, 10th Ed. Chest Pain & Acute Coronary Syndromes. Elsevier; 2023.- hs-troponin detects myocardial injury, not aetiology. It rises in PE, sepsis, heart failure, myocarditis, renal failure and tachyarrhythmia — a raised value is not automatically an MI.
- The change (delta) over time and the clinical context distinguish acute MI from chronic elevation. Validated 0/1h and 0/2h algorithms (ESC) rule-in and rule-out rapidly.
- A very low presentation value with a low-risk score and non-ischaemic ECG has a high negative predictive value — the basis of accelerated discharge pathways.
Scores 0–2 each for History, ECG, Age, Risk factors, Troponin:
- 0–3 (low): ~1–2% 6-week major adverse cardiac event — candidate for early discharge with a rule-out troponin pathway.
- 4–6 (moderate): admit/observe for serial troponin and further testing.
- ≥7 (high): high MACE risk — early invasive/aggressive management.
The HEART Pathway (HEART score + 0/3h troponin) safely discharges low-risk patients and outperforms TIMI/GRACE for undifferentiated ED chest pain.
Work-up & Evidence-Based Approach
PE: apply Wells/PERC; if PE cannot be excluded → age-adjusted D-dimer or CTPA. A raised troponin in PE reflects RV strain, not ACS.
Ischaemic heart disease presents a decade earlier in South Asians and often atypically; maintain a low threshold in younger patients with risk factors. Access to timely primary PCI is uneven — pharmaco-invasive strategy (fibrinolysis at the first hospital, then transfer for PCI) is a mainstay where a cath lab is not immediately reachable.
High-sensitivity troponin is not universally available; where only conventional troponin exists, serial sampling over longer intervals and clinical scores carry more weight. Consider regional causes of chest pain (e.g. rheumatic valve disease, TB pericarditis, scorpion-sting myocarditis) alongside the classic six.
Drug Reference — Acute Chest Pain / ACS
| Drug | Indication | Dose | Notes |
|---|---|---|---|
| Aspirin | Suspected ACS | 300 mg PO/chewed loading, then 75 mg OD | Give early unless dissection strongly suspected/allergy |
| Ticagrelor / clopidogrel | ACS (dual antiplatelet) | Ticagrelor 180 mg → 90 mg BD; clopidogrel 300–600 mg → 75 mg | Per pathway; avoid ticagrelor if high bleeding risk / recent thrombolysis considerations |
| GTN (nitroglycerin) | Ischaemic pain / pulmonary oedema | Sublingual 0.3–0.6 mg; IV infusion titrated | Avoid in RV infarct, severe AS, and recent PDE5 inhibitor use (hypotension) |
| Morphine | Refractory ischaemic pain | 2–4 mg IV titrated | Use sparingly — may blunt P2Y₁₂ absorption; masks symptoms |
| Heparin (UFH/LMWH) | ACS anticoagulation | Per ACS protocol | Withhold if aortic dissection not excluded |
| Esmolol / labetalol | Aortic dissection (rate then BP) | Titrate to HR <60, then SBP 100–120 | Beta-block before vasodilator to avoid reflex tachycardia/shear |
| Tenecteplase / alteplase | STEMI when timely PCI unavailable | Weight-based bolus (TNK) | Pharmaco-invasive; screen contraindications; not if dissection possible |
Undifferentiated Chest Pain Pathway
Immediate — is this patient crashing?
- Vitals (both arms), monitor, IV, O₂ if hypoxic, ECG within 10 min
- Unstable? → treat the killer: tension pneumothorax (decompress), tamponade (echo → drain), STEMI (cath lab), dissection (CT + rate/BP control)
Read the ECG
- STEMI / STEMI-equivalent → reperfusion (PCI ≤120 min, else fibrinolysis)
- Ischaemic changes / arrhythmia → treat as ACS, admit
- Add posterior (V7–9) and right-sided (V4R) leads when indicated
Stable, non-diagnostic ECG → risk-stratify
- Focused history; consider PE (Wells/PERC), dissection features, Boerhaave history
- Serial hs-troponin (0/1h or 0/2h) + HEART score
- Bedside echo/lung US, CXR as indicated
Disposition
- Low risk (HEART 0–3, negative troponin protocol, non-ischaemic ECG): safe discharge with follow-up
- Moderate: observe, complete serial troponin, provocative/anatomical testing
- High: admit; early invasive management
Safety-net & document
- Give clear return advice; document the reasoning that excluded each killer
- Re-ECG and re-examine if pain recurs or evolves
Common Mistakes in Chest Pain
A single normal ECG misses evolving ACS and a single early troponin can be falsely reassuring. Repeat the ECG with symptoms and complete a serial troponin protocol before ruling out.
Reproducible tenderness, relief with antacids, or atypical features do not exclude MI — especially in women, the elderly and diabetics. Let objective testing, not the story alone, close a dangerous diagnosis.
Treating presumed ACS in an unrecognised dissection is catastrophic. Look for pulse/BP differentials, tearing/migrating pain and a wide mediastinum, and image before committing to antithrombotics in the at-risk patient.
Inferior STEMI with hypotension may be a preload-dependent RV infarct — nitrates and morphine can cause profound hypotension. Get a V4R, give fluids, and avoid vasodilators.
Troponin marks myocardial injury of any cause (PE, sepsis, heart failure, myocarditis, renal failure). Use the delta and context; a type 2 MI or non-ACS elevation needs different management.
Tension pneumothorax is a clinical diagnosis (unilateral absent breath sounds, tracheal deviation, distended neck veins, shock). Decompress immediately — do not wait for the CXR.
Severe chest/epigastric pain after vomiting with subcutaneous emphysema or effusion suggests oesophageal rupture — a rapidly fatal, easily missed cause needing CT and urgent surgical involvement.
Exam Pearls
Q: Name the six immediately life-threatening causes of chest pain.
ACS, aortic dissection, pulmonary embolism, tension pneumothorax, cardiac tamponade, and oesophageal rupture (Boerhaave).
Q: What is the target time for the first ECG, and for STEMI reperfusion?
ECG within 10 minutes of arrival. Primary PCI within 120 min of diagnosis; otherwise fibrinolysis within 10 min of STEMI diagnosis, then transfer.
Q: What are the components of the HEART score and its low-risk cut-off?
History, ECG, Age, Risk factors, Troponin (0–2 each). 0–3 = low risk (~1–2% MACE) — candidate for early discharge with a troponin rule-out pathway.
Q: Why avoid nitrates in inferior STEMI with hypotension?
Possible RV infarction, which is preload-dependent; nitrates/morphine drop preload → severe hypotension. Confirm with V4R, give fluids.
Q: How do you differentiate an acute MI from chronic troponin elevation?
By the dynamic change (delta) over serial samples plus ECG and clinical context, using 0/1h or 0/2h hs-troponin algorithms — a stable elevation suggests chronic injury.
Q: What features suggest aortic dissection, and how does management differ?
Tearing/migrating pain, pulse/BP differential, new AR, wide mediastinum → CT aortogram. Control heart rate before blood pressure (esmolol/labetalol), and avoid antithrombotics.
Q: What is the pharmaco-invasive strategy?
Fibrinolysis at the first medical contact when timely primary PCI is unavailable, followed by transfer for early angiography/PCI — important in Indian settings with variable cath-lab access.
Q: How does a raised troponin fit PE?
It reflects RV strain and marks higher-risk PE (prognostic), not coronary occlusion — don't misroute a PE patient into an ACS pathway.
References
- Tintinalli JE, et al. Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9th Edition. Chest Pain. McGraw-Hill; 2020.
- Walls RM, Hockberger RS, Gausche-Hill M, et al. Rosen's Emergency Medicine: Concepts and Clinical Practice, 10th Edition. Elsevier; 2023.
- Byrne RA, Rossello X, Coughlan JJ, et al. (ESC). 2023 ESC Guidelines for the management of acute coronary syndromes. Eur Heart J. 2023;44:3720–3826.
- Gulati M, Levy PD, Mukherjee D, et al. (ACC/AHA). 2021 Guideline for the Evaluation and Diagnosis of Chest Pain. Circulation. 2021;144:e368–e454.
- Six AJ, Backus BE, Kelder JC. Chest pain in the emergency room: value of the HEART score. Neth Heart J. 2008;16:191–196.
- Mahler SA, Riley RF, Hiestand BC, et al. The HEART Pathway randomized trial. Circ Cardiovasc Qual Outcomes. 2015;8:195–203.
- Collet JP, Thiele H, et al. (ESC). 0/1h and 0/2h high-sensitivity troponin algorithms for NSTE-ACS. Eur Heart J. (NSTE-ACS guidance).