What is the recommended immediate management of acute coronary syndrome, including STEMI and non‑ST‑segment elevation ACS?

Immediate Management of Acute Coronary Syndrome

All patients with suspected ACS must receive a 12-lead ECG within 10 minutes of first medical contact to differentiate STEMI from NSTE-ACS, as this single test determines the entire treatment pathway. 1

Initial Assessment and Triage

ECG-Based Classification

• STEMI patients require immediate reperfusion with primary PCI within 90 minutes (direct presentation) or 120 minutes (transfer); if these time windows cannot be met, administer fibrinolytic therapy immediately 1, 2
• NSTE-ACS patients (including NSTEMI and unstable angina) require risk stratification to determine timing of invasive strategy 3, 1
• Continuous cardiac monitoring should be initiated immediately for at least 24 hours to detect life-threatening arrhythmias 1

Immediate Laboratory Testing

• High-sensitivity cardiac troponin measurement on arrival with results available within 60 minutes 1
• Use a 0-hour/1-hour algorithm for rapid rule-in/rule-out when hs-cTn is available, or 0-hour/2-hour as alternative 1
• Additional blood work: serum creatinine, hemoglobin, hematocrit, platelet count, blood glucose, and INR if on anticoagulation 3

Immediate Pharmacological Management

Antiplatelet Therapy (Start Immediately)

Dual antiplatelet therapy is the cornerstone of ACS treatment and must be initiated immediately upon diagnosis. 1

• Aspirin 150–300 mg (non-enteric coated) loading dose, followed by 75–100 mg daily indefinitely 1, 4
• Plus a P2Y12 inhibitor (choose one based on clinical scenario):

P2Y12 Inhibitor Selection:

• Ticagrelor 180 mg loading, then 90 mg twice daily is preferred for all moderate-to-high-risk patients regardless of management strategy (medical or invasive) 1, 5
• Prasugrel 60 mg loading, then 10 mg daily for patients proceeding to PCI with known coronary anatomy; contraindicated in patients with prior stroke/TIA, age ≥75 years, or weight <60 kg 3, 1
• Clopidogrel 300–600 mg loading, then 75 mg daily reserved for patients unable to receive ticagrelor or prasugrel, or requiring concomitant oral anticoagulation 1, 6, 4

Critical Pitfall: Do not administer prasugrel before coronary anatomy is known, as it must be discontinued 7 days before CABG and carries higher bleeding risk 3, 1

Anticoagulation (Start Immediately)

• Fondaparinux is preferred for medically managed patients due to lower bleeding risk 1
• Enoxaparin (LMWH) is an acceptable alternative and superior to unfractionated heparin 1, 4
• Unfractionated heparin should be used when PCI is planned within hours or in renal dysfunction 1

Additional Immediate Therapies

• High-intensity statin (atorvastatin 40–80 mg or rosuvastatin 20–40 mg) started immediately 1
• Nitroglycerin (sublingual or IV) for ongoing chest pain; titrate until symptoms resolve or blood pressure normalizes 1
• Morphine (IV or subcutaneous) for refractory pain, though be aware it may delay absorption of oral P2Y12 inhibitors 3, 1
• Supplemental oxygen only if saturation <90% or respiratory distress—routine oxygen is not beneficial 3, 1
• Beta-blocker (oral) within 24 hours if no contraindications (heart failure, hypotension, bradycardia) 1

Risk Stratification and Timing of Invasive Strategy for NSTE-ACS

Very High-Risk: Immediate Angiography (<2 hours)

Perform immediate coronary angiography for any of the following 1:

• Hemodynamic instability or cardiogenic shock
• Recurrent or refractory chest pain despite medical therapy
• Life-threatening arrhythmias or cardiac arrest
• Mechanical complications of MI (acute mitral regurgitation, ventricular septal defect, free wall rupture)
• Acute heart failure with refractory angina or ST-segment deviation

High-Risk: Early Angiography (<24 hours)

Angiography within 24 hours for patients with 3, 1:

• Rise or fall in cardiac troponin
• Dynamic ST-segment or T-wave changes
• GRACE score >140

Intermediate-Risk: Angiography (<72 hours)

Angiography within 72 hours for patients with 1:

• Diabetes mellitus
• Renal insufficiency (eGFR <60 mL/min/1.73 m²)
• Left ventricular ejection fraction <40% or heart failure
• GRACE score 109–140
• Prior PCI or CABG

Critical Pitfall: Do not delay dual antiplatelet therapy while awaiting angiography—both aspirin and P2Y12 inhibitor should be given immediately upon diagnosis 1

STEMI-Specific Reperfusion Strategy

Primary PCI is the gold standard for STEMI and must be performed within 90 minutes (direct presentation) or 120 minutes (transfer). 1, 2

• If PCI cannot be achieved within 120 minutes, administer fibrinolytic therapy immediately (alteplase, reteplase, or tenecteplase at full dose for age <75 years; half dose for age ≥75 years) 2
• After fibrinolysis, transfer for angiography within 24 hours 2

Critical Pitfall: Do not postpone reperfusion in STEMI while awaiting biomarker results—the ECG diagnosis alone mandates immediate action 1

Glycoprotein IIb/IIIa Inhibitors

• Eptifibatide or tirofiban should be considered for moderate-to-high-risk NSTE-ACS patients in addition to aspirin and heparin, particularly if proceeding to PCI 3, 7, 4
• Administer eptifibatide as 180 mcg/kg IV bolus followed by 2 mcg/kg/min infusion (reduce to 1 mcg/kg/min if creatinine clearance <50 mL/min) 7

Long-Term Secondary Prevention

Dual Antiplatelet Therapy Duration

• 12 months of aspirin plus P2Y12 inhibitor for all ACS survivors 1
• Shorter duration (3–6 months) may be considered in high bleeding risk patients 1

Additional Long-Term Therapies

• High-intensity statin continued indefinitely 1
• ACE inhibitor (or ARB if intolerant) for LVEF ≤40%, heart failure, hypertension, or diabetes 3, 1
• Beta-blocker for LVEF ≤40% 3, 1
• Mineralocorticoid receptor antagonist (eplerenone preferred) for LVEF ≤35% with heart failure or diabetes, if no renal dysfunction or hyperkalemia 1
• Smoking cessation, dietary modification, and cardiac rehabilitation are essential 3, 1

Common Pitfalls to Avoid

• Never use fibrinolysis in NSTE-ACS—it is contraindicated and harmful 1
• Do not withhold antithrombotic therapy due to bleeding concerns in acute phase—mortality risk from untreated ACS far exceeds bleeding risk 8
• Avoid routine morphine use as it may delay absorption of oral P2Y12 inhibitors 1
• Do not give nitrates if phosphodiesterase-5 inhibitor taken within 24 hours (sildenafil/vardenafil) or 48 hours (tadalafil) due to severe hypotension risk 8
• Avoid concomitant use of clopidogrel with omeprazole or esomeprazole as they significantly reduce antiplatelet activity 6