Acute Coronary Syndrome (ACS): Diagnosis and Emergency Management
Written by Dr. Muhammad Salar Raza · Manually reviewed by Dr. Muhammad Salar Raza · Content updated
Clinical Pathway
Suspect ACS in any patient with prolonged ischemic chest pain, and obtain a 12-lead ECG within 10 minutes of arrival. Give chewable aspirin 162-325 mg and draw high-sensitivity troponin. ST-segment elevation (STEMI) requires immediate reperfusion: primary PCI within 90 minutes of first medical contact, or fibrinolysis within 30 minutes if timely PCI is unavailable. NSTEMI and unstable angina are managed with dual antiplatelet therapy, anticoagulation, high-intensity statin, and risk-stratified invasive evaluation. Treat pain with nitrates if no contraindication, control blood pressure and heart rate with a beta blocker once stable, and screen for complications such as arrhythmia and acute heart failure.
Clinical Reasoning
The ECG and troponin divide chest pain into STEMI, NSTEMI, and unstable angina, and this split drives every downstream decision. Troponin may be normal in the first 1-2 hours, so a single early negative result never excludes ACS; serial testing at 0 and 1 or 3 hours is the standard. New ST elevation in contiguous leads, or a new left bundle branch block with compatible symptoms, mandates reperfusion without waiting for troponin. Remember the STEMI equivalents and mimics: posterior infarction (ST depression in V1-V3), right ventricular infarction with inferior STEMI (avoid nitrates), pericarditis, and aortic dissection.
Sample MCQ
A 60-year-old man presents with 90 minutes of severe substernal chest pain radiating to his left arm. His ECG shows ST-segment elevation in leads V1 to V4. He is at a PCI-capable hospital and has no contraindications. What is the most appropriate next step in management?
- AEmergent primary percutaneous coronary intervention
- BIntravenous fibrinolytic therapy
- CSerial troponin measurements with observation
- DOutpatient exercise stress testing
Correct Answer: Emergent primary percutaneous coronary intervention
ST elevation in contiguous precordial leads confirms an acute anterior STEMI, and immediate reperfusion is the priority. Primary PCI is preferred when it can be performed within 90 minutes of first medical contact at a PCI-capable centre, as it restores perfusion more reliably and with less bleeding risk than fibrinolysis. Fibrinolysis is reserved for patients who cannot reach timely PCI, ideally within 30 minutes of arrival. Observation with serial troponins is appropriate for suspected NSTEMI without ST elevation, not for STEMI where delay costs myocardium. Outpatient stress testing is used for stable chest pain, never for an acute presentation.
Guidelines and further reading
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Related Clinical Topics
Stable Angina Pectoris: Clinical Evaluation
Stable angina is characterized by episodic chest discomfort that is predictably provoked by exertion or emotional stress and relieved by rest or nitroglycerin. The initial evaluation involves a thorough history and physical examination, followed by a resting ECG. If the patient can exercise and has a normal resting ECG, an exercise stress test (treadmill ECG) is the preferred initial non-invasive functional test for diagnosing ischemic heart disease. Patients with abnormal resting ECGs or inability to exercise require imaging-based stress testing (e.g., stress echocardiography or nuclear perfusion imaging).
Heart Failure with Reduced Ejection Fraction: Diagnosis and Management
Heart Failure with Reduced Ejection Fraction (HFrEF) is a clinical syndrome characterized by the heart's inability to pump sufficient blood to meet the body's metabolic demands due to impaired systolic function of the left ventricle, typically defined by a left ventricular ejection fraction (LVEF) of 40% or less. Treatment for HFrEF focuses on guideline-directed medical therapy (GDMT) including angiotensin receptor-neprilysin inhibitors (ARNI), beta-blockers, mineralocorticoid receptor antagonists (MRA), and sodium-glucose cotransporter-2 (SGLT2) inhibitors to reduce mortality and morbidity. Diuretics are used for symptom relief from congestion, and device therapies like implantable cardioverter-defibrillators (ICD) or cardiac resynchronization therapy (CRT) may be indicated for selected patients. Lifestyle modifications, such as dietary sodium restriction and fluid management, are also crucial. Patients commonly present with progressive exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and fatigue due to reduced forward flow. Physical signs may include peripheral edema, jugular venous distension, pulmonary rales (crackles), an S3 gallop, and hepatomegaly, indicating fluid congestion.
Acute Heart Failure: Diagnosis and Management
Acute heart failure presents with dyspnea, orthopnea, pulmonary crackles, elevated jugular venous pressure, and peripheral edema. Stabilize airway, breathing, and circulation first, give oxygen only if hypoxemic, and obtain an ECG, chest X-ray, BNP or NT-proBNP, and bedside echocardiogram. Patients with congestion and adequate blood pressure (warm and wet) receive intravenous loop diuretics such as furosemide, with vasodilators added if hypertensive. Hypoperfused patients (cold and wet) may need inotropes and urgent cardiology involvement. Always identify and treat the trigger: ischemia, arrhythmia, uncontrolled hypertension, infection, or non-adherence to medications.
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