What is the management of acute coronary syndrome (ACS)?

Management of Acute Coronary Syndrome

All patients with suspected ACS require immediate 12-lead ECG within 10 minutes of presentation, aspirin 150-300mg loading dose, and continuous cardiac monitoring, with management pathway determined by presence or absence of ST-segment elevation. 1, 2

Immediate Assessment (First 10 Minutes)

Critical Initial Actions

• Obtain 12-lead ECG within 10 minutes to differentiate STEMI from NSTE-ACS, as this determines the entire treatment pathway 1
• Administer aspirin 150-300mg loading dose immediately (chewed for faster absorption) unless contraindicated 1, 2, 3
• Establish continuous cardiac rhythm monitoring to detect life-threatening arrhythmias, particularly ventricular fibrillation which is the major preventable cause of early death 1, 2, 3
• Assess vital signs focusing on blood pressure, heart rate, oxygen saturation, and signs of hemodynamic instability (hypotension, pulmonary rales indicating heart failure) 1

Blood Work on Arrival

• Draw high-sensitivity cardiac troponin (preferably troponin T or I) with results available within 60 minutes 1
• Repeat troponin measurement at 1-3 hours if high-sensitivity assays are used 1, 2
• Additional labs: serum creatinine, hemoglobin, hematocrit, platelet count, blood glucose, and INR if on anticoagulation 1

Risk Stratification and Treatment Pathway

STEMI (ST-Segment Elevation Present)

• Immediate emergency transport to PCI-capable hospital with goal of first medical contact to device time ≤90 minutes 1
• Activate cardiac catheterization team en route with advance notification 1
• Administer primary PCI within 120 minutes as this reduces mortality compared to delayed intervention 4

NSTE-ACS (No Persistent ST-Elevation)

Very High-Risk Criteria (Immediate Invasive Strategy <2 Hours): 1, 2

• Hemodynamic instability or cardiogenic shock
• Recurrent or ongoing chest pain refractory to medical treatment
• Life-threatening arrhythmias (ventricular tachycardia, ventricular fibrillation)
• Mechanical complications of MI
• Acute heart failure

High-Risk Criteria (Early Invasive Strategy <24 Hours): 1, 2

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

Intermediate-Risk Criteria (Invasive Strategy <72 Hours): 1, 2

• Diabetes mellitus
• Renal insufficiency (eGFR <60 mL/min/1.73m²)
• Left ventricular ejection fraction <40%
• Early post-infarction angina
• Recent PCI or prior CABG
• GRACE score 109-140

Pharmacological Management

Antiplatelet Therapy (Dual Antiplatelet Therapy - DAPT)

Aspirin: 1, 2, 3

• Loading dose: 150-300mg immediately (or 75-325mg per some guidelines)
• Maintenance: 75-150mg daily indefinitely

P2Y12 Inhibitor (choose one): 1, 2

• Ticagrelor (preferred over clopidogrel): 180mg loading dose, then 90mg twice daily for 12 months
• Prasugrel: 60mg loading dose, then 10mg daily for 12 months (contraindicated if prior stroke/TIA, age ≥75 years, weight <60kg) 5
• Clopidogrel: 300-600mg loading dose, then 75mg daily for 12 months (if ticagrelor/prasugrel contraindicated)

Critical Timing Consideration: In NSTE-ACS, P2Y12 inhibitor administration can be delayed until coronary anatomy is known to avoid excessive bleeding risk if urgent CABG is needed 1, 2

Anticoagulation (Choose One Agent)

For Conservative or Early Invasive Strategy: 1, 2, 3

• Enoxaparin: 1mg/kg subcutaneously every 12 hours (preferred; lower risk of heparin-induced thrombocytopenia)
• Fondaparinux: 2.5mg subcutaneously once daily (associated with less bleeding than enoxaparin in conservative management)
• Unfractionated heparin: IV bolus 60-70 units/kg (max 5000 units), then infusion 12-15 units/kg/hour (max 1000 units/hour) adjusted to aPTT 1.5-2.5 times control

Continue anticoagulation until revascularization or hospital discharge 1, 2

Anti-Ischemic Therapy

Nitrates (for ongoing chest pain): 1, 2, 3

• Sublingual nitroglycerin 0.4mg every 5 minutes for up to 3 doses
• If pain persists: IV nitroglycerin starting at 5-10 mcg/min, titrate by 10 mcg/min every 3-5 minutes until pain relief or blood pressure limits reached
• Contraindications: Systolic BP <90mmHg, severe bradycardia (<50 bpm), right ventricular infarction, phosphodiesterase inhibitor use within 24-48 hours

Beta-Blockers: 1, 2, 3

• Initiate oral beta-blocker promptly unless contraindicated
• Target heart rate 50-60 beats per minute
• Contraindications: Signs of heart failure, evidence of low output state, increased risk for cardiogenic shock, PR interval >0.24 seconds, second or third-degree heart block, active asthma/reactive airway disease

Calcium Channel Blockers: 1, 2

• Consider only if beta-blockers contraindicated or inadequate symptom control
• Avoid in patients with heart failure or left ventricular dysfunction

Additional Therapies for Mortality Reduction

High-Intensity Statin Therapy: 1, 2, 4, 3

• Initiate immediately regardless of baseline LDL cholesterol
• Atorvastatin 80mg daily or rosuvastatin 40mg daily
• Target LDL <70 mg/dL or 50% reduction from baseline

ACE Inhibitors: 4, 3

• Start within 24 hours if LVEF <40%, anterior MI, heart failure, hypertension, or diabetes mellitus
• Continue indefinitely

Glycoprotein IIb/IIIa Inhibitors: 1, 2, 3

• Consider in very high-risk patients undergoing early invasive strategy
• Administer during or immediately before PCI
• Continue for 12-24 hours post-procedure

Special Populations and Considerations

Patients with Cardiogenic Shock

• Emergency coronary angiography regardless of time delay from symptom onset 1
• Emergency PCI of culprit lesion if anatomy amenable 1
• Emergency CABG if anatomy not amenable to PCI 1
• Routine IABP use is NOT recommended 1

Elderly Patients (≥75 Years)

• Apply same diagnostic and invasive strategies as younger patients 1
• Prasugrel generally not recommended due to increased risk of fatal and intracranial bleeding, except in high-risk situations (diabetes or prior MI) 5
• Adjust antithrombotic dosing based on renal function 1

Low Body Weight (<60 kg)

• Consider reducing prasugrel maintenance dose to 5mg daily due to increased bleeding risk 5
• Standard dosing for other agents with careful monitoring

Chronic Kidney Disease

• Apply same diagnostic and therapeutic strategies with dose adjustments 1
• Assess kidney function by eGFR in all patients 1
• Use low- or iso-osmolar contrast media at lowest possible volume during invasive procedures 1

Common Pitfalls to Avoid

Delayed ECG: Waiting beyond 10 minutes for ECG can result in missed diagnosis and delayed reperfusion, directly impacting mortality 1, 2

Premature P2Y12 Inhibitor Administration: In NSTE-ACS patients, administering P2Y12 inhibitors before knowing coronary anatomy increases bleeding risk in those requiring urgent CABG without clear benefit 1, 2

Missing Atypical Presentations: ACS presents atypically in women, elderly, and diabetic patients—isolated dyspnea, epigastric pain, or syncope without chest pain should raise suspicion 4, 6

Inappropriate Discharge: Between 2-5% of ACS patients are inappropriately discharged from emergency departments; maintain high index of suspicion even with normal initial troponin if clinical suspicion is high 7

Discontinuing Antiplatelet Therapy: Stopping prasugrel or other P2Y12 inhibitors in the first few weeks after ACS significantly increases risk of subsequent cardiovascular events 5

Ignoring Hemodynamic Instability: Patients with ongoing ischemia and hemodynamic compromise require immediate coronary angiography regardless of ECG or biomarker findings to prevent life-threatening arrhythmias 1

Waiting for Troponin Results: In high-risk patients with clear clinical presentation, do not delay aspirin, anticoagulation, or transfer to PCI-capable facility while waiting for troponin results 2