What is the current management of myocardial infarction (MI) in a hospital setting?

Management of Myocardial Infarction in Hospital Setting

Primary PCI is the preferred reperfusion strategy for acute myocardial infarction when available within 120 minutes of first medical contact, with fibrinolytic therapy as an alternative if PCI cannot be performed within this timeframe, as recommended by the European Society of Cardiology. 1

Initial Assessment and Diagnosis

• Perform 12-lead ECG within 10 minutes of first medical contact
• Look for ST-segment elevation or new left bundle branch block
• Obtain high-sensitivity cardiac troponin levels
• Establish diagnosis based on:
  • Rise and/or fall of cardiac troponin with at least one value above the 99th percentile
  • Symptoms of ischemia
  • New ECG changes
  • Imaging evidence of new loss of viable myocardium

Immediate Management

Reperfusion Strategy

1. Primary PCI:

   • Preferred when available within 120 minutes of first medical contact
   • Door-to-balloon time goal: <90 minutes

2. Fibrinolytic Therapy:

   • When PCI cannot be performed within 120 minutes
   • Door-to-needle time goal: <30 minutes
   • Use fibrin-specific agents (tenecteplase, alteplase, or reteplase)
   • Transfer to PCI-capable center immediately after fibrinolysis

Antithrombotic Therapy

• Antiplatelet Therapy:

  • Loading dose of aspirin (160-325 mg)
  • P2Y12 inhibitor loading dose:
    • Ticagrelor (180 mg) or prasugrel (60 mg) preferred over clopidogrel (600 mg)
    • Note: Prasugrel is contraindicated in patients with history of stroke/TIA or active bleeding 2

• Anticoagulation:

  • For primary PCI: Unfractionated heparin, enoxaparin, or bivalirudin
  • For fibrinolysis: Enoxaparin (preferred) or unfractionated heparin

Additional Immediate Measures

• Oxygen therapy if saturation <90%
• Pain relief with intravenous opioids (morphine) plus antiemetic
• Nitrates for ongoing chest pain without hypotension
• Monitor vital signs and cardiac rhythm continuously

Post-Reperfusion Care

Monitoring and Assessment

• Continuous ECG monitoring for at least 24 hours
• Echocardiography during hospitalization to assess:
  • Left ventricular function
  • Mechanical complications
  • Presence of LV thrombus 1

Rescue PCI

• Indicated when fibrinolysis has failed (<50% ST-segment resolution at 60-90 min)
• Indicated for hemodynamic or electrical instability
• Indicated for worsening ischemia 3

Pharmacological Therapy

• Beta-blockers:

  • Start IV metoprolol in hemodynamically stable patients 4
  • Continue with oral therapy (metoprolol 50 mg every 6 hours for 48 hours, then 100 mg twice daily) 4
  • Avoid in patients with hypotension, acute heart failure, AV block, or severe bradycardia 3

• ACE inhibitors:

  • Start within 24 hours in patients with:
    • Heart failure
    • LV systolic dysfunction
    • Diabetes
    • Anterior infarct 3, 1

• Statins:

  • Start high-intensity statin therapy as early as possible
  • Target LDL-C <70 mg/dL 3, 1

Hospital Discharge and Secondary Prevention

Antithrombotic Strategy

• Dual Antiplatelet Therapy (DAPT):
  • Aspirin (75-100 mg daily) indefinitely
  • P2Y12 inhibitor (preferably ticagrelor or prasugrel) for 12 months
  • Consider PPI in patients at high risk of gastrointestinal bleeding 3, 1

Other Secondary Prevention Medications

• Beta-blockers:

  • Indicated for patients with heart failure and/or LVEF <40% 3, 1

• ACE inhibitors/ARBs:

  • Continue in patients with heart failure, LV dysfunction, diabetes, or anterior MI
  • ARBs (preferably valsartan) as alternative for ACE inhibitor-intolerant patients 3

• Mineralocorticoid Receptor Antagonists (MRAs):

  • For patients with LVEF <40% and heart failure or diabetes 3, 1

Lifestyle Modifications

• Smoking cessation with support, nicotine replacement therapies, varenicline, and bupropion
• Participation in cardiac rehabilitation program
• Regular physical activity
• Diet low in saturated fat and cholesterol
• Blood pressure control (target <130/80 mmHg) 1

Special Considerations

Cardiogenic Shock

• Immediate invasive strategy with revascularization
• Consider mechanical circulatory support
• Invasive hemodynamic monitoring

Elderly Patients (≥75 years)

• Careful dosing of antithrombotic agents
• Prasugrel generally not recommended except in high-risk patients (diabetes or prior MI) 2

Mechanical Complications

• Echocardiography to detect:
  • Ventricular septal rupture
  • Papillary muscle rupture/severe mitral regurgitation
  • Free wall rupture
  • Consider urgent surgical intervention if detected

Common Pitfalls and Caveats

• Delaying reperfusion therapy while waiting for cardiac biomarker results
• Failure to recognize atypical ECG presentations of MI
• Inappropriate use of prasugrel in patients with history of stroke/TIA
• Premature discontinuation of DAPT increases risk of stent thrombosis
• Inadequate secondary prevention measures leading to recurrent events
• Failure to transfer patients to PCI-capable centers after fibrinolysis