What are the ACC/AHA guideline recommendations for antithrombotic and reperfusion therapy in acute ST‑segment‑elevation myocardial infarction?

ACC/AHA Guidelines for STEMI Management

Immediate Actions at First Medical Contact (≤10 Minutes)

Obtain a 12-lead ECG within 10 minutes of first medical contact and immediately administer aspirin 162-325 mg orally (chewable) or 250-500 mg IV if the patient cannot swallow. 1, 2

• Activate the catheterization laboratory immediately upon STEMI diagnosis without waiting for additional testing 2
• Initiate continuous ECG monitoring with defibrillator capacity 1, 2
• Avoid routine supplemental oxygen unless oxygen saturation is <90% 2

Reperfusion Strategy Selection: The 120-Minute Rule

Primary PCI is the preferred reperfusion strategy when it can be performed within 120 minutes of STEMI diagnosis (90 minutes if presenting directly to a PCI-capable hospital). 1, 2, 3

Choose Primary PCI When:

• First-medical-contact-to-device time ≤120 minutes 1, 2
• Door-to-balloon time ≤90 minutes at PCI-capable facilities 1
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department 1, 2

Choose Fibrinolytic Therapy When:

• Primary PCI cannot be performed within 120 minutes of diagnosis 1, 2, 4
• Target: administer fibrinolytic within 10-30 minutes of diagnosis ("door-to-needle" ≤30 minutes) 1
• Greatest benefit occurs within first 3 hours of symptom onset 4

Mandatory Primary PCI Regardless of Time Delay:

• Cardiogenic shock or acute severe heart failure 1, 2
• Contraindications to fibrinolytic therapy (active bleeding, recent stroke, prior intracranial hemorrhage) 1, 2
• Failed fibrinolysis (persistent symptoms or <50% ST-segment resolution at 60-90 minutes) 2, 4

Antithrombotic Therapy for Primary PCI

Administer aspirin immediately, then add a potent P2Y12 inhibitor (prasugrel 60 mg or ticagrelor 180 mg loading dose) before or at the time of PCI. 1, 2

Antiplatelet Regimen:

• Aspirin: 162-325 mg oral (chewable) or 250-500 mg IV, then 75-100 mg daily indefinitely 1, 2
• P2Y12 inhibitor: Prasugrel 60 mg loading dose OR ticagrelor 180 mg loading dose (clopidogrel 75 mg only if these are unavailable) 1, 2
• Continue dual antiplatelet therapy (DAPT) for 12 months post-PCI 1, 2

Anticoagulation During PCI:

• Unfractionated heparin: 100 U/kg IV bolus (reduce to 60 U/kg if GPIIb/IIIa inhibitor used) 1, 2
• Enoxaparin or bivalirudin are acceptable alternatives 2
• Fondaparinux is contraindicated for primary PCI 1, 2, 4

Fibrinolytic Strategy Protocol

Use a fibrin-specific agent (tenecteplase, alteplase, or reteplase) within 10-30 minutes of diagnosis, preferably in the pre-hospital setting. 1, 4, 5

Fibrinolytic Agent Selection:

• Tenecteplase, alteplase, or reteplase preferred over streptokinase 1, 4, 5
• For symptom duration <6 hours, alteplase or tenecteplase superior to streptokinase 5

Adjunctive Therapy with Fibrinolysis:

• Aspirin: Oral or IV immediately 1, 4
• Clopidogrel: 75 mg daily (NOT prasugrel or ticagrelor with fibrinolysis) 1, 4
• Enoxaparin: IV bolus followed by subcutaneous dosing (preferred over UFH) 4
• Continue anticoagulation for at least 48 hours, up to 8 days or until revascularization 1, 2

Post-Fibrinolysis Management:

• Transfer all patients to PCI-capable center immediately after fibrinolysis 4
• Perform routine angiography 2-24 hours after successful fibrinolysis 1, 4
• Switch from clopidogrel to prasugrel or ticagrelor at time of PCI 4
• Perform immediate rescue PCI if reperfusion fails 2, 4

Absolute Contraindications to Fibrinolytic Therapy

Do not administer fibrinolytics if any of the following are present: 1

• Any prior intracranial hemorrhage 1
• Known structural cerebrovascular lesion (e.g., AVM) 1
• Known malignant intracranial neoplasm 1
• Ischemic stroke within 3 months (except acute ischemic stroke within 3 hours) 1
• Suspected aortic dissection 1
• Active bleeding or bleeding diathesis 1
• Significant closed head or facial trauma within 3 months 1

In-Hospital Management

Oral Medications (Initiate Within 24 Hours):

• Beta-blockers: Start orally in patients with heart failure and/or LVEF <40% unless contraindicated 1, 2
• ACE inhibitors: Initiate within 24 hours in patients with heart failure, LV dysfunction, diabetes, or anterior infarct 2
• High-intensity statin: Start immediately with target LDL-C <70 mg/dL or ≥50% reduction 6, 2

Monitoring and Assessment:

• Perform routine echocardiography during hospitalization to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 6, 2, 4
• Obtain fasting lipid profile within 24 hours 2

Intravenous Beta-Blockers:

Do not routinely administer IV beta-blockers in STEMI—they may be considered only for treatment of hypertension if no contraindications exist. 1

Special Clinical Scenarios

Late Presentation (>12 Hours):

• Reperfusion therapy (preferably primary PCI) indicated if evidence of ongoing ischemia, even if symptoms started >12 hours prior 1
• Primary PCI may be considered in stable patients presenting 12-24 hours after symptom onset 1
• Routine PCI of totally occluded artery >24 hours after symptom onset in stable patients without ischemia is NOT recommended 1

Cardiac Arrest with STEMI:

• Patients with resuscitated cardiac arrest and ST-elevation on post-resuscitation ECG should undergo immediate primary PCI 2
• Initiate targeted temperature management early in unresponsive patients 2

Non-Infarct-Related Artery Lesions:

• Evaluate severe non-IRA stenoses before hospital discharge, either during index PCI or staged procedure 2
• In cardiogenic shock, perform non-IRA PCI during index procedure 2

Critical Pitfalls to Avoid

• Never delay primary PCI to "stabilize" the patient—time is myocardium, and every minute counts 1, 2, 3
• Do not withhold aspirin due to bleeding concerns—the mortality benefit in STEMI outweighs bleeding risk 1, 6
• Do not use prasugrel or ticagrelor as initial P2Y12 inhibitor with fibrinolytic therapy—clopidogrel is specifically indicated 4
• Do not administer routine IV beta-blockers—associated with increased early mortality 1
• Do not use fondaparinux for primary PCI—it is contraindicated 1, 2, 4
• Do not discontinue NSAIDs (except aspirin) before STEMI—they increase mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1
• Do not miss the 2-24 hour window for routine angiography after successful fibrinolysis—all patients require transfer and angiography 4

Systems of Care Requirements

• PCI-capable centers must provide 24/7, no-delay service 2
• Regional STEMI networks should coordinate EMS and hospitals with standardized protocols 1, 2
• EMS must alert PCI center immediately after selecting reperfusion strategy 2
• Pre-hospital fibrinolysis protocols are reasonable if EMS is appropriately trained and staffed 1