Latest Protocol for Myocardial Infarction (2025 ACC/AHA Guideline)

1. Initial Evaluation & Diagnosis

• 12-lead ECG within 10 minutes of first medical contact (FMC)
• High-sensitivity cardiac troponin (hs-cTn) is the preferred biomarker — enables 0/1h or 0/2h rapid rule-in/rule-out algorithms
• Classify as: STEMI (ST elevation ≥1mm in ≥2 contiguous leads, or new LBBB), NSTEMI, or Unstable Angina (UA)
• Differentiating Type 1 MI (plaque rupture/thrombosis) from Type 2 MI (supply-demand mismatch) is critical — the 2025 guideline focuses on Type 1

2. STEMI — Reperfusion Strategy

Primary PCI (preferred)

Fibrinolysis (if PCI unavailable within 120 min)

• Administer within 30 minutes of FMC
• Agents: tenecteplase (TNK), alteplase, reteplase
• Pharmacoinvasive strategy: Transfer to PCI-capable center after lytic therapy; angiography within 3–24 hours if successful reperfusion; immediate rescue PCI if reperfusion fails

3. NSTEMI/Unstable Angina — Invasive Strategy

4. Antithrombotic Therapy

Antiplatelet Therapy

• Aspirin 162–325 mg loading dose, then 75–100 mg daily indefinitely — Class I
• P2Y12 inhibitor (DAPT): Begin at diagnosis
  • Ticagrelor 180 mg load → 90 mg BID (preferred over clopidogrel in most ACS)
  • Prasugrel 60 mg load → 10 mg daily (avoid if prior stroke/TIA; preferred in PCI-treated patients with no contraindication)
  • Clopidogrel 300–600 mg load → 75 mg daily (use when ticagrelor/prasugrel contraindicated)
• DAPT duration: Typically 12 months post-ACS; can be shortened to 6 months in high bleeding risk, or extended >12 months in high ischemic/low bleeding risk

Anticoagulation

• Unfractionated heparin (UFH) or bivalirudin (preferred during PCI to reduce bleeding)
• Enoxaparin (LMWH) acceptable for NSTEMI conservative management
• Stop parenteral anticoagulation after PCI unless specific indication
• Fondaparinux is an option in NSTEMI (avoid in primary PCI — risk of catheter thrombosis)

GP IIb/IIIa Inhibitors

• Routine use is no longer recommended; reserved for bailout situations (large thrombus burden, no-reflow, inadequate P2Y12 loading)

5. Adjunctive Pharmacotherapy (Acute Phase)

6. Multivessel Disease Management

• STEMI patients: Complete revascularization of non-culprit arteries is reasonable at index procedure or staged (Class IIa) — based on COMPLETE, FULL REVASC, and FIRE trials
  • Complete revascularization reduces recurrent MI and repeat revascularization
  • Exception: Cardiogenic shock — culprit-only PCI is recommended (CULPRIT-SHOCK trial)
• NSTEMI patients: Role of multivessel vs culprit-only PCI remains an open evidence gap

7. Special Situations

Cardiogenic Shock (Killip Class IV)

• Emergency revascularization (PCI or CABG) is the only proven mortality benefit — Class I
• Intra-aortic balloon pump (IABP): No longer routinely recommended (neutral in IABP-SHOCK II)
• Impella/ECMO: May be considered in selected patients; evidence still evolving

CABG Indications

• Left main or complex 3-vessel disease with high SYNTAX score
• Failed PCI or anatomy not suitable for PCI
• Urgent/emergency CABG in cardiogenic shock without viable PCI option

Anemia in MI (new 2025 recommendation)

• Liberal transfusion strategy (transfuse if Hgb <10 g/dL) is recommended over restrictive strategy — based on the MINT trial, which showed higher 30-day death/re-MI in the restrictive group (16.9% vs 14.5%)

8. Long-term Secondary Prevention

9. Post-MI Complications

Key 2025 Updates vs Prior Guidelines

1. Unified STEMI + NSTEMI into a single ACS guideline (replacing separate 2013/2014 documents)
2. Liberal transfusion in anemic MI patients (new, based on MINT trial)
3. Complete revascularization in stable STEMI explicitly supported (Class IIa)
4. DAPT de-escalation strategies (switching from prasugrel/ticagrelor to clopidogrel) recognized as reasonable in bleeding-risk patients
5. SGLT2 inhibitors and GLP-1 agonists integrated into post-MI care for appropriate patients
6. Colchicine post-MI no longer routinely recommended for prevention of recurrent CV events (LoDoCo2/COLCOT caveats addressed)

Source: 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes — Rao SV et al., Circulation 2025 (PMID 40014670, DOI: 10.1161/CIR.0000000000001309). Also: Fuster and Hurst's The Heart, 15th Edition; Braunwald's Heart Disease, 12th Edition.

⚠️ Note: An erratum for this guideline has been published (PMID 41212941 in Circulation; PMID 41432333 in JACC) — review for any corrections before clinical implementation.