What is the treatment for myocardial infarction (heart attack)?

Treatment of Myocardial Infarction (Heart Attack)

The immediate treatment for myocardial infarction includes oxygen administration, aspirin (160-325mg), sublingual nitroglycerin (unless contraindicated by hypotension or extreme heart rates), adequate analgesia with morphine or diamorphine, and rapid reperfusion therapy with either thrombolysis or primary percutaneous coronary intervention for patients with ST-segment elevation. 1, 2

Initial Assessment and Management

• Evaluation should ideally be completed within 10 minutes of arrival to the emergency department, with no more than 20 minutes elapsing before assessment 1, 2
• A 12-lead ECG should be obtained immediately to identify ST-segment elevation (≥1mV) in contiguous leads or new left bundle branch block, which indicates need for reperfusion therapy 1, 2
• Initial treatment should include:
  • Oxygen via nasal prongs 1, 2
  • Sublingual nitroglycerin (unless systolic BP <90mmHg or heart rate <50 or >100bpm) 1
  • Aspirin 160-325mg orally 1, 3
  • Adequate analgesia with IV morphine or diamorphine with concurrent antiemetics 1, 2

Reperfusion Therapy

• Patients with ST-segment elevation MI or new LBBB should receive immediate reperfusion therapy 1
• Time is critical - greatest benefit occurs when reperfusion is initiated within 6 hours of symptom onset 1, 2
• Thrombolytic therapy effectiveness is time-dependent:
  • Within first hour: 35 lives saved per 1000 patients treated
  • 7-12 hours: 16 lives saved per 1000 patients treated 1
• Primary percutaneous coronary intervention (PCI) is preferred when available in a timely manner by skilled personnel with access to emergency CABG 1
• Target "call to needle time" should be within 90 minutes of alerting medical services 1

Medication Management

• Early intravenous β-adrenergic blocker therapy followed by oral therapy should be initiated regardless of whether reperfusion therapy was given 1
• For patients with heart failure, administer diuretics (usually IV furosemide) and afterload-reducing agents 1
• For patients with cardiogenic shock, consider insertion of hemodynamic support devices 1
• For right ventricular infarction, provide vigorous intravascular volume expansion with normal saline and inotropic agents if hypotension persists 1

Hospital Management

• Continuous cardiac monitoring should be established immediately 2
• Monitor for complications including arrhythmias, which are most common in the first 24 hours 2
• For patients with large anterior MI or LV mural thrombus, consider anticoagulation with heparin 1
• Patients with recurrent chest pain due to pericarditis should receive high-dose aspirin (650mg every 4-6 hours) 1
• Recurrent chest pain due to ischemia should be treated with IV nitroglycerin, analgesics, and antithrombotic medications 1

Special Considerations

• Elderly patients (>65 years), those with low body weight (<70kg), hypertension, or receiving tissue plasminogen activator have increased risk of intracranial hemorrhage with thrombolytic therapy 1, 2
• Diabetic patients require strict glycemic control with insulin-glucose infusion followed by multiple-dose insulin treatment to reduce long-term mortality 1
• Calcium channel blockers have not been shown to reduce mortality in acute MI and may be harmful in certain patients with cardiovascular disease 1

Preparation for Discharge and Long-term Management

• Before discharge, patients should undergo exercise testing to assess functional capacity and stratify risk 1
• Long-term management includes:
  • Continued aspirin, β-blocker, and ACE inhibitor therapy 1
  • Diet low in saturated fat and cholesterol 1
  • LDL cholesterol reduction to <100 mg/dL if elevated despite diet 1
  • Smoking cessation 1, 4
  • Participation in a formal cardiac rehabilitation program 1

Common Pitfalls to Avoid

• Delaying ECG assessment beyond 10 minutes of arrival 2
• Withholding aspirin while waiting for definitive diagnosis 2
• Administering thrombolytics to patients without ST-elevation or with contraindications 1
• Failing to provide adequate analgesia, which can increase sympathetic activation 2
• Delaying reperfusion therapy, as benefit is time-dependent 1, 5
• Failing to recognize atypical presentations in women, diabetic patients, and elderly patients 1