What should a provider do if an adult patient with no significant allergies or contraindications presents with Acute Coronary Syndrome (ACS)?

Immediate Management of Acute Coronary Syndrome

For an adult patient presenting with ACS without contraindications, immediately administer aspirin 162-325 mg (chewable preferred), initiate dual antiplatelet therapy with a P2Y12 inhibitor (preferably ticagrelor 180 mg loading dose), start parenteral anticoagulation, obtain a 12-lead ECG within 10 minutes, and arrange urgent coronary angiography based on risk stratification. 1, 2

Initial Assessment and ECG (Within 10 Minutes)

• Perform 12-lead ECG immediately (within 10 minutes of presentation) to distinguish between ST-elevation myocardial infarction (STEMI) and non-ST-elevation ACS (NSTE-ACS) 1, 3
• Obtain high-sensitivity cardiac troponin measurements at presentation and after 1 hour (or 3-6 hours if high-sensitivity assay unavailable) 1, 4
• Initiate continuous multi-lead ECG monitoring for ischemia and arrhythmias 4
• Monitor vital signs, oxygen saturation, and assess for hemodynamic instability 1, 4

Immediate Pharmacological Management

Antiplatelet Therapy (Administer Immediately)

• Aspirin 162-325 mg loading dose (chewable preferred for faster absorption) should be given immediately unless true aspirin allergy exists 5, 1, 2

  • If aspirin was not given prehospital, this is the first medication to administer 5
  • Continue with 75-100 mg daily maintenance dose 1, 4

• Add a P2Y12 inhibitor for dual antiplatelet therapy (DAPT) 1, 2

  • Ticagrelor is preferred: 180 mg loading dose, then 90 mg twice daily for moderate-to-high risk patients 1, 2
  • Alternative: Clopidogrel 300-600 mg loading dose, then 75 mg daily (though ticagrelor is superior) 5, 6
  • Continue DAPT for 12 months unless contraindicated 1, 4

Anticoagulation (Initiate Immediately)

• Start parenteral anticoagulation immediately with one of the following 2, 4:
  • Enoxaparin 1 mg/kg subcutaneously every 12 hours (adjust for renal function if creatinine clearance <50 mL/min) 5, 2
  • Unfractionated heparin: 60-70 units/kg bolus (maximum 5000 units), then 12-15 units/kg/hour infusion targeting aPTT 1.5-2.0 times control 5, 2
  • Fondaparinux or bivalirudin are reasonable alternatives for specific scenarios 5

Symptom Management

• Oxygen therapy only if indicated: Administer oxygen if oxygen saturation <94%, dyspnea, hypoxemia, or signs of heart failure are present; titrate to maintain saturation ≥94% 5

  • Do not routinely administer oxygen to uncomplicated ACS patients 5

• Nitroglycerin for symptom relief: Sublingual nitroglycerin (up to 3 doses at 3-5 minute intervals), followed by IV nitroglycerin if chest pain persists 5, 4

  • Contraindications: Systolic blood pressure <90 mm Hg, right ventricular infarction, or use of phosphodiesterase-5 inhibitors within 24 hours (48 hours for tadalafil) 5

• Morphine for persistent severe chest pain: 2-4 mg IV, titrated to pain relief, particularly in STEMI or when chest pain is unresponsive to nitrates 5, 4

Beta-Blockers

• Oral beta-blockers should be initiated within the first 24 hours once the patient is stabilized, starting with low doses 5
• Do not routinely administer IV beta-blockers in the prehospital or early ED setting 5
• IV beta-blockers may be considered for specific situations such as severe hypertension or tachyarrhythmias without contraindications 5
• Contraindications: Moderate-to-severe heart failure, bradycardia (<60 bpm), hypotension (SBP <100 mm Hg), second- or third-degree heart block, or reactive airway disease 5

Statin Therapy

• Initiate high-intensity statin therapy as early as possible (e.g., atorvastatin 80 mg or rosuvastatin 40 mg daily) 5, 1, 4

Risk Stratification and Timing of Invasive Strategy

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

• Hemodynamic instability or cardiogenic shock 1, 2
• Recurrent or ongoing chest pain refractory to medical treatment 1, 2
• Life-threatening arrhythmias or cardiac arrest 1
• Mechanical complications of MI 1
• High-risk ECG pattern: ST elevation in aVR with diffuse ST depression (indicates left main or severe three-vessel disease) 2

High-Risk (Early Invasive Strategy <24 Hours)

• Rise or fall in cardiac troponin compatible with MI 1
• Dynamic ST-segment or T-wave changes 1, 2
• GRACE score >140 4

Intermediate-Risk (Invasive Strategy <72 Hours)

• Diabetes mellitus 1, 4
• Renal insufficiency (eGFR <60 mL/min/1.73 m²) 1, 4
• Prior MI or coronary revascularization 1

STEMI-Specific Management

• Primary percutaneous coronary intervention (PCI) within 120 minutes of first medical contact reduces mortality from 9% to 7% 3
• If PCI within 120 minutes is not possible, administer fibrinolytic therapy (alteplase, reteplase, or tenecteplase at full dose for patients <75 years; half dose for ≥75 years), followed by transfer for PCI within 24 hours 3
• Transport directly to PCI-capable facility, bypassing closer hospitals if transport time <30 minutes and first medical contact-to-balloon time can be <90 minutes 5

NSTE-ACS Specific Considerations

• GPIIb/IIIa inhibitors (eptifibatide) may be added for high-risk patients undergoing PCI: 180 mcg/kg IV bolus immediately before PCI, followed by 2 mcg/kg/min infusion, with second bolus 10 minutes after first 1, 7
• For patients with creatinine clearance <50 mL/min, reduce eptifibatide infusion to 1 mcg/kg/min 7

Critical Pitfalls to Avoid

• Do not delay angiography to 24-72 hours for patients with ST elevation in aVR with diffuse ST depression—this pattern requires immediate (<2 hour) catheterization 2
• Do not administer NSAIDs (other than aspirin)—they may be harmful and should be discontinued 5
• Do not routinely give IV beta-blockers early—multiple studies show no benefit and potential for increased cardiogenic shock 5
• Do not withhold anticoagulation while awaiting angiography—all ACS patients require parenteral anticoagulation 4
• Monitor for thrombocytopenia (platelet count <100,000/mL or >50% drop from baseline) and immediately discontinue GPIIb/IIIa inhibitors and heparin if it occurs 5

Secondary Prevention (Initiate Before Discharge)

• Continue DAPT for 12 months 1, 4
• High-intensity statin therapy long-term 1, 4
• ACE inhibitors for patients with LVEF ≤40%, heart failure, hypertension, or diabetes 5, 1, 4
• Beta-blockers particularly for patients with reduced LV function (LVEF ≤40%) 5, 1, 4
• Smoking cessation, cardiac rehabilitation enrollment, and lifestyle modifications 4, 8