What are the immediate treatment guidelines for acute coronary infarct (myocardial infarction)?

Immediate Treatment Guidelines for Acute Coronary Infarction (Myocardial Infarction)

The immediate management of acute myocardial infarction requires rapid assessment, timely reperfusion therapy, and administration of key medications including aspirin, P2Y12 inhibitors, anticoagulants, and adjunctive therapies to reduce mortality and improve outcomes.

Initial Assessment and Management (First 10-20 Minutes)

• Perform rapid evaluation within 10 minutes (maximum 20 minutes) of arrival to the emergency department 1, 2
• Obtain a 12-lead ECG immediately to identify ST-segment elevation or new left bundle branch block 2
• Establish continuous cardiac monitoring with defibrillation capacity 2
• Administer oxygen by nasal prongs (only if oxygen saturation <90%) 1, 2
• Provide adequate analgesia with morphine sulfate or meperidine for pain relief 1
• Administer aspirin 160-325 mg orally (or IV if unable to swallow) immediately 1, 2
• Perform rapid triage for reperfusion therapy based on ECG findings 1

Reperfusion Strategy

For ST-Elevation MI (STEMI):

• Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy when it can be performed within 120 minutes of STEMI diagnosis by an experienced team 1, 2
• Transfer patients directly to the catheterization laboratory, bypassing the emergency department 1, 2
• If primary PCI cannot be performed in a timely manner (within 120 minutes), administer fibrinolytic therapy within 12 hours of symptom onset 1, 2

Antithrombotic Therapy with Primary PCI:

• Administer a potent P2Y12 inhibitor (prasugrel or ticagrelor, or clopidogrel if these are unavailable) before or at the time of PCI 1, 2
• Continue dual antiplatelet therapy (DAPT) for 12 months unless contraindicated due to bleeding risk 1, 2
• Use unfractionated heparin as anticoagulation during PCI 1, 2
• Avoid fondaparinux for primary PCI 1, 2

Fibrinolytic Therapy (if PCI is delayed):

• Initiate fibrinolytic therapy as soon as possible, preferably in pre-hospital setting 1, 2
• Use a fibrin-specific agent (tenecteplase, alteplase, or reteplase) 1, 2
• Administer oral or IV aspirin 1, 2
• Add clopidogrel to aspirin 1, 2
• Provide anticoagulation until revascularization or for the duration of hospital stay (up to 8 days) with either:
  • Enoxaparin IV followed by SC (preferred over UFH) 1, 2
  • Unfractionated heparin as weight-adjusted IV bolus followed by infusion 1, 2
• Transfer to a PCI-capable center immediately after fibrinolysis 1, 2
• Perform rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) 1, 2

First 24-48 Hours Management

• Continue aspirin 160-325 mg daily 1
• Administer intravenous beta-blockers (e.g., metoprolol) in hemodynamically stable patients 1, 3
  • Give three bolus injections of 5 mg metoprolol IV at approximately 2-minute intervals 3
  • Follow with oral metoprolol 50 mg every 6 hours for 48 hours, then 100 mg twice daily 3
• Infuse intravenous nitroglycerin for 24-48 hours in patients without hypotension, bradycardia, or excessive tachycardia 1
• Administer magnesium sulfate as needed to replete magnesium deficits 1
• For patients receiving alteplase, continue intravenous heparin for an additional 48 hours 1
• Perform routine echocardiography to assess LV and RV function, detect mechanical complications, and exclude LV thrombus 1, 2

Pharmacological Management

• Start high-intensity statin therapy as early as possible 1, 2
• Initiate ACE inhibitors within 24 hours in patients with heart failure, LV systolic dysfunction, diabetes, or anterior infarct 2
• Continue beta-blockers for at least 6 weeks 1
• Consider proton pump inhibitors in combination with DAPT for patients at high risk of gastrointestinal bleeding 1, 2

Management of Complications

• For heart failure: Administer diuretics (usually IV furosemide) and afterload-reducing agents 1
• For cardiogenic shock: Consider hemodynamic support devices and perform emergency angiography and PCI 1, 2
• For right ventricular infarction: Provide vigorous intravascular volume expansion with normal saline and inotropic agents if hypotension persists 1
• For recurrent chest pain due to pericarditis: Administer high-dose aspirin (650 mg every 4-6 hours) 1
• For recurrent chest pain due to ischemia: Treat with IV nitroglycerin, analgesics, and antithrombotic medications 1

Common Pitfalls to Avoid

• Delaying ECG interpretation beyond 10 minutes of arrival 1, 2
• Administering thrombolytics to patients without ST-segment elevation 1
• Delaying reperfusion therapy when indicated 1, 2
• Using fondaparinux for primary PCI 1, 2
• Administering IV beta-blockers to patients with hypotension, acute heart failure, AV block, or severe bradycardia 1
• Using calcium channel blockers as they have not shown mortality benefit and may be harmful in certain patients 1
• Administering routine oxygen therapy to patients with oxygen saturation ≥90% 2

Preparation for Discharge

• Plan for standard exercise testing before discharge or shortly thereafter 1
• Ensure patient is discharged on appropriate medications:
  • Aspirin 75-100 mg daily indefinitely 1, 2
  • DAPT for 12 months 1, 2
  • Beta-blockers 1
  • ACE inhibitors 1
  • High-intensity statins with goal LDL <1.8 mmol/L (70 mg/dL) 1, 2
• Provide smoking cessation counseling with pharmacological support 1, 2
• Recommend participation in a cardiac rehabilitation program 1, 2