What is the management for acute myocardial infarct?

Management of Acute Myocardial Infarction

The management of acute myocardial infarction requires immediate administration of aspirin 160-325 mg, intravenous β-blockers followed by oral therapy, adequate analgesia with morphine, and reperfusion therapy for patients with ST-segment elevation or new LBBB. 1

Initial Management in the Emergency Department

First 10-20 Minutes

• Oxygen: Administer by nasal prongs (2-4 L/min) if breathlessness or heart failure is present 1
• Aspirin: Give 160-325 mg immediately 2, 1
• Nitroglycerin: Administer sublingual nitroglycerin unless:
  • Systolic BP <90 mmHg
  • Heart rate <50 or >100 bpm 2
• Analgesia: Provide morphine sulfate (4-8 mg IV initially, with 2-8 mg IV every 5-15 minutes as needed) 1, 3
• 12-lead ECG: Perform immediately to guide reperfusion decisions 2

Reperfusion Strategy

For patients with ST-segment elevation or new LBBB:

1. Thrombolytic therapy:

   • Most beneficial when initiated within 6 hours of symptom onset
   • Still effective up to 12 hours after symptom onset
   • Reduces 35-day mortality by 21% 2

2. Primary PCI:

   • Alternative to thrombolytic therapy if performed promptly by skilled personnel
   • Requires backup emergency CABG availability 2

Hospital Management

First 24-48 Hours

• Aspirin: Continue 160-325 mg daily 2, 1
• β-blockers:
  • Start with IV metoprolol: three bolus injections of 5 mg at 2-minute intervals
  • Follow with oral metoprolol 50 mg every 6 hours for 48 hours
  • Then maintain at 100 mg orally twice daily 4
• Nitroglycerin: Infuse IV for 24-48 hours if no hypotension, bradycardia, or tachycardia 2, 1
• Continuous cardiac monitoring: For arrhythmia detection 2
• Heparin: Consider for patients with large anterior MI or LV mural thrombus 2

Management of Complications

Cardiogenic Shock

• Assess for hypotension and signs of tissue hypoperfusion
• Evaluate LV function with echocardiography
• Consider:
  • Intra-aortic balloon pump
  • Emergency coronary angiography
  • Revascularization (PTCA or CABG) 2, 1
• For right ventricular infarction: Aggressive intravascular volume expansion with normal saline and inotropic agents if hypotension persists 2

Heart Failure

• Administer IV furosemide
• Add afterload-reducing agent 2

Recurrent Chest Pain

• If due to pericarditis: High-dose aspirin (650 mg every 4-6 hours)
• If due to ischemia: IV nitroglycerin, analgesics, and antithrombotic medications 2

Preparation for Discharge

• Exercise testing:
  • Submaximal at 4-7 days, or
  • Symptom-limited at 10-14 days 2
• Medication regimen:
  • Aspirin: 160-325 mg daily indefinitely
  • β-blocker: Continue for at least 6 weeks
  • ACE inhibitor: Selected dose 2

Long-Term Management

• Lifestyle modifications:
  • Achieve ideal weight
  • Low saturated fat and cholesterol diet
  • Smoking cessation
  • Regular exercise (20 minutes of brisk walking at least three times weekly) 2
• Lipid management:
  • Target LDL <100 mg/dL
  • Drug therapy if LDL >130 mg/dL despite diet 2
• Cardiac rehabilitation 2

Important Considerations

• The benefit of reperfusion therapy is time-dependent, with greatest benefit when initiated within the first hour of symptom onset 2
• Low-dose aspirin (162 mg) may be as effective as and potentially safer than higher doses (325 mg) for acute treatment of STEMI 5, 6
• Avoid thrombolytic therapy in patients without ST-segment elevation 2
• Have emergency equipment readily available: atropine, lidocaine, transcutaneous pacing patches, transvenous pacemaker, defibrillator, and epinephrine 2

The management of acute MI requires prompt recognition and treatment, with the goal of early reperfusion to salvage myocardium and reduce mortality. The time-dependent nature of interventions cannot be overemphasized, as delays in treatment significantly impact outcomes.