What is the management of STEMI (ST-Elevation Myocardial Infarction) vs NSTEMI (Non-ST-Elevation Myocardial Infarction)?

Management of STEMI vs NSTEMI

The fundamental difference in management is that STEMI requires immediate reperfusion therapy (primary PCI within 90-120 minutes or fibrinolysis within 30 minutes), while NSTEMI management is risk-stratified with early invasive strategy within 24 hours for high-risk patients or within 2 hours for unstable patients. 1, 2

Initial Management (First 10 Minutes) - Identical for Both

• Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to differentiate STEMI from NSTEMI 1, 2
• Administer aspirin 162-325 mg (chewed) immediately unless contraindicated 1, 2
• Initiate continuous ECG monitoring with defibrillator capacity 2
• Avoid routine oxygen therapy unless oxygen saturation is <90% 2
• Assess vital signs, focused history for symptom onset time, and identify contraindications to reperfusion 1

STEMI-Specific Reperfusion Strategy

Primary PCI (Preferred Method)

Primary PCI is mandatory when it can be performed with first medical contact-to-device time ≤90 minutes at PCI-capable centers or ≤120 minutes with transfer. 1, 2

• Transport patients directly to the catheterization laboratory, bypassing the emergency department 2
• Administer a potent P2Y12 inhibitor before or at the time of PCI: prasugrel (60 mg loading dose) or ticagrelor preferred over clopidogrel 2, 3
• Give unfractionated heparin IV bolus at 100 U/kg (60 U/kg if glycoprotein IIb/IIIa inhibitors are used) 2
• Use radial access and drug-eluting stents as standard of care 2
• Do not perform routine thrombus aspiration or deferred stenting 2

Fibrinolytic Therapy (When PCI Delayed)

If primary PCI cannot be performed within 120 minutes of first medical contact, administer fibrinolytic therapy within 30 minutes of arrival. 1, 2

• Use fibrin-specific agents: tenecteplase (single weight-adjusted IV bolus 30-50 mg), alteplase, or reteplase 2
• For patients ≥75 years old, reduce tenecteplase dose by 50% to minimize stroke risk 2
• Administer aspirin and clopidogrel with fibrinolysis 2
• Continue anticoagulation with unfractionated heparin or enoxaparin for at least 48 hours, preferably for duration of hospitalization (up to 8 days) 2
• Monitor for successful reperfusion at 60-90 minutes: assess symptom relief and ≥50% reduction in ST-segment elevation 2

Critical Timing Considerations

• Symptom onset within 12 hours mandates immediate reperfusion therapy 1, 2
• Pre-hospital fibrinolysis should be initiated when appropriate to minimize delay 2
• Direct transport to PCI-capable hospitals when possible to avoid transfer delays 1

NSTEMI-Specific Invasive Strategy

Risk Stratification Determines Timing

High-risk NSTEMI patients (GRACE score >140 or TIMI risk score >4) require early invasive strategy with coronary angiography within 24 hours. 1

Immediate invasive approach within 2 hours is mandatory for:

• Refractory angina despite medical therapy 1
• Hemodynamic instability or cardiogenic shock 1
• Life-threatening arrhythmias 1
• Acute heart failure 1

Pharmacological Management

• Dual antiplatelet therapy: aspirin plus P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) 1
• Anticoagulation with unfractionated heparin or low-molecular-weight heparin 1
• Consider glycoprotein IIb/IIIa inhibitors in high thrombus burden cases 1

Common Pharmacological Therapy (Both STEMI and NSTEMI)

Dual Antiplatelet Therapy (DAPT)

• Continue DAPT for 12 months after PCI unless contraindications exist 2
• Maintenance dosing: aspirin 75-100 mg daily indefinitely plus P2Y12 inhibitor 2
• For prasugrel: consider reducing maintenance dose to 5 mg daily in patients <60 kg due to increased bleeding risk 3
• Add proton pump inhibitor in patients at high risk of gastrointestinal bleeding 2

Additional Medications

• Initiate high-intensity statin therapy as early as possible 2
• Start beta-blockers orally in patients with heart failure and/or LVEF <40% unless contraindicated 2
• Begin ACE inhibitors within 24 hours in patients with heart failure, LV systolic dysfunction, diabetes, or anterior infarct 2

Special Populations and Situations

Cardiogenic Shock

• Emergency angiography and PCI are recommended regardless of time from symptom onset 2
• CABG is indicated for patients <75 years old with shock within 36 hours of STEMI who have severe multivessel or left main disease, if revascularization can be performed within 18 hours of shock 4

Cardiac Arrest

• Pursue primary PCI strategy in patients with cardiac arrest and ST-elevation on post-resuscitation ECG 2
• Therapeutic hypothermia is recommended for comatose STEMI patients after out-of-hospital cardiac arrest due to ventricular fibrillation or pulseless ventricular tachycardia 1

Emergency CABG Indications

Emergency CABG is indicated for: 4

• Failed PCI with persistent pain or hemodynamic instability in patients with suitable coronary anatomy
• Persistent or recurrent ischemia refractory to medical therapy with significant myocardium at risk
• Surgical repair of post-infarction ventricular septal rupture or mitral valve insufficiency
• Life-threatening ventricular arrhythmias with ≥50% left main stenosis and/or triple-vessel disease

Critical Pitfalls to Avoid

Diagnostic Errors

• Do not miss STEMI equivalents: hyperacute T-waves, true posterior MI (ST depression in V1-V4 with ST elevation in posterior leads V7-V9), or multilead ST depression with ST elevation in aVR suggesting left main or multivessel disease 1, 5
• Recognize that left circumflex artery occlusion presents as NSTEMI in >50% of cases due to absence of ST-elevation on standard 12-lead ECG, but requires urgent revascularization 6
• Atypical presentations are common in women, elderly, and diabetic patients who may present without chest pain 1, 2

Treatment Delays

• Never delay ECG acquisition beyond 10 minutes of first medical contact 1
• Do not overlook high-risk NSTEMI patients who need urgent invasive management within 2 hours 1
• Avoid administering prasugrel loading dose until coronary anatomy is established in UA/NSTEMI patients to prevent excessive bleeding if urgent CABG is required 3

Medication Management

• Do not start prasugrel in patients with history of TIA or stroke (absolute contraindication) 3
• Prasugrel is generally not recommended in patients ≥75 years old except in high-risk situations (diabetes or prior MI) 3
• When possible, discontinue prasugrel at least 7 days prior to any surgery 3
• Do not discontinue antiplatelet therapy prematurely, particularly in the first few weeks after ACS, as this increases risk of subsequent cardiovascular events 3

Procedural Considerations

• Fondaparinux is not recommended for primary PCI 2
• Do not perform routine PCI immediately after successful fibrinolysis in the absence of contemporary evidence 4