What is the recommended immediate management and treatment for an adult patient presenting with acute coronary syndrome?

Treatment of Acute Coronary Syndrome

Immediate Assessment and ECG-Based Triage

All patients with suspected ACS must have a 12-lead ECG obtained and interpreted within 10 minutes of first medical contact to determine whether STEMI or NSTE-ACS is present, as this dictates the entire treatment pathway. 1, 2, 3

• STEMI patients (persistent ST-elevation >20 minutes) require immediate reperfusion therapy with primary PCI within 90-120 minutes of first medical contact, or fibrinolytic therapy if PCI cannot be achieved within this window 1, 2, 4
• NSTE-ACS patients (transient ST-depression, T-wave inversion, or normal ECG) require risk stratification and timing of invasive strategy based on clinical presentation 1

Immediate Medical Therapy (All ACS Patients)

Antiplatelet Therapy

Administer aspirin 150-300 mg loading dose (non-enteric coated) immediately, followed by 75-100 mg daily, plus a P2Y12 inhibitor loading dose. 1, 2, 3, 5, 6

For P2Y12 inhibitor selection:

• Ticagrelor (180 mg loading, then 90 mg twice daily) is recommended for all moderate-to-high risk patients regardless of initial strategy, including those pretreated with clopidogrel 1, 6
• Prasugrel (60 mg loading, then 10 mg daily) is recommended for patients proceeding to PCI with known coronary anatomy, but is contraindicated in patients with prior stroke/TIA, age ≥75 years, or weight <60 kg 1, 6
• Clopidogrel (300-600 mg loading, then 75 mg daily) is reserved for patients who cannot receive ticagrelor or prasugrel, or who require oral anticoagulation 1

Anticoagulation

Initiate parenteral anticoagulation immediately with one of the following: 1, 2, 5

• Fondaparinux (preferred for medically managed patients due to lower bleeding risk) 1
• Enoxaparin (low-molecular-weight heparin) 1, 2
• Unfractionated heparin (preferred if PCI planned within hours or renal dysfunction present) 1, 5
• Bivalirudin (alternative for PCI patients) 5

Additional Immediate Therapies

• High-intensity statin therapy should be initiated immediately (atorvastatin 40-80 mg or rosuvastatin 20-40 mg) 1
• Nitroglycerin sublingual or IV for ongoing chest pain 1, 5
• Morphine IV or subcutaneous for refractory chest pain 1, 5
• Oxygen only if SpO2 <90% or respiratory distress (not routinely) 1
• Beta-blocker oral within 24 hours if no contraindications (heart failure, hypotension, bradycardia) 1, 5

Risk Stratification and Timing of Invasive Strategy

Very High-Risk (Immediate Invasive Strategy <2 Hours)

Proceed to immediate coronary angiography (<2 hours) if any of the following are present: 1, 2, 3

• Hemodynamic instability or cardiogenic shock 1
• Recurrent or ongoing chest pain refractory to medical treatment 1
• Life-threatening arrhythmias or cardiac arrest 1
• Mechanical complications of MI (acute mitral regurgitation, ventricular septal defect, free wall rupture) 1, 2
• Acute heart failure with refractory angina or ST-segment deviation 1

High-Risk (Early Invasive Strategy <24 Hours)

Perform coronary angiography within 24 hours if any of the following are present: 1, 2, 3

• Rise or fall in cardiac troponin compatible with MI 1
• Dynamic ST-segment or T-wave changes (symptomatic or silent) 1
• GRACE score >140 1

Intermediate-Risk (Invasive Strategy <72 Hours)

Perform coronary angiography within 72 hours if any of the following are present: 1

• Diabetes mellitus 1
• Renal insufficiency (eGFR <60 mL/min/1.73 m²) 1
• LVEF <40% or congestive heart failure 1
• GRACE score 109-140 1
• Prior PCI or CABG 1

Cardiac Biomarker Testing

Measure high-sensitivity cardiac troponin (hs-cTn) on arrival with results available within 60 minutes. 1, 3

• Use 0h/1h algorithm with repeat measurement at 1 hour for rapid rule-in/rule-out if hs-cTn assay available 1, 3
• Use 0h/2h algorithm as alternative with repeat at 2 hours 1, 3
• Use 0h/3-6h protocol if conventional troponin assay used (not high-sensitivity) 1, 3

Critical pitfall: Using a 1-hour repeat interval with conventional troponin (which requires 3-6 hours) can lead to premature discharge of evolving MI patients 3

STEMI-Specific Reperfusion Strategy

Primary PCI is the preferred reperfusion strategy and must be performed within 90 minutes of first medical contact for patients presenting directly to PCI-capable centers, or within 120 minutes for transferred patients. 1, 2, 3, 4

If PCI cannot be achieved within 120 minutes, administer fibrinolytic therapy: 1, 4

• Alteplase, reteplase, or tenecteplase at full dose for patients <75 years without contraindications 4
• Half-dose for patients ≥75 years 4
• Streptokinase at full dose if cost is a consideration 4
• Transfer for PCI within 24 hours after fibrinolysis 4

Every 30-minute delay in reperfusion increases mortality measurably. 3

Long-Term Secondary Prevention

All ACS patients require the following long-term therapies: 1

• Dual antiplatelet therapy for 12 months (aspirin plus P2Y12 inhibitor) unless high bleeding risk warrants shorter duration (3-6 months) 1, 6
• High-intensity statin continued indefinitely 1
• ACE inhibitor (or ARB if intolerant) for patients with LVEF ≤40%, heart failure, hypertension, or diabetes 1
• Beta-blocker for patients with LVEF ≤40% 1
• Mineralocorticoid receptor antagonist (eplerenone preferred) for patients with LVEF ≤35% and heart failure or diabetes, without significant renal dysfunction or hyperkalemia 1
• Smoking cessation, dietary modification, and cardiac rehabilitation 1

Critical Pitfalls to Avoid

• Do not delay reperfusion in STEMI patients waiting for biomarker results; ECG findings alone mandate immediate action 1, 3, 4
• Do not administer prasugrel before coronary anatomy is known, as it is contraindicated in patients requiring CABG within 5-7 days 1
• Obtain posterior leads (V7-V9) when anterior ST-depression is present to avoid missing posterior STEMI 3
• Do not routinely use intra-aortic balloon pump in cardiogenic shock without mechanical complications 2
• Avoid morphine in patients with NSTE-ACS when possible, as it may delay absorption of oral P2Y12 inhibitors 1