What is the initial treatment for a patient experiencing a myocardial infarction (heart attack)?

Treatment for Heart Attack

Immediate treatment for a patient experiencing a myocardial infarction requires rapid administration of aspirin (160-325mg chewed), oxygen if hypoxic, sublingual nitroglycerin (unless contraindicated), intravenous morphine for pain relief, and urgent reperfusion therapy—either thrombolysis within 90 minutes of first medical contact or primary percutaneous coronary intervention—with the greatest mortality benefit achieved when treatment begins within the first hour of symptom onset. 1

Time-Critical Initial Actions

The cornerstone of heart attack management is minimizing time to treatment, as mortality benefit is directly time-dependent 2:

• Within the first hour: Thrombolytic therapy saves 65 lives per 1000 patients treated 2
• 2-3 hours: 27 lives saved per 1000 patients 2
• 4-6 hours: 25 lives saved per 1000 patients 2

Target "call-to-needle time" should be ≤90 minutes from when the patient alerts medical services to receiving reperfusion therapy 2, 1.

Immediate Medications (First 10 Minutes)

Aspirin

• Administer 160-325mg orally immediately (chewable or water-soluble formulation for faster absorption) 2, 1, 3
• Aspirin reduces mortality in acute MI and should not be delayed while awaiting definitive diagnosis 1, 3

Oxygen

• Provide oxygen via nasal prongs, especially for patients who are breathless or have heart failure 1
• Oxygen administration helps reduce myocardial ischemia 2

Nitroglycerin

• Give sublingual nitroglycerin unless contraindicated 2, 1
• Contraindications: Systolic BP <90mmHg, heart rate <50 or >100 bpm 1
• Patients may take up to 3 doses (one every 5 minutes); if symptoms persist after 3 doses, emergency transport is mandatory 2

Analgesia

• Intravenous morphine 4-8mg initially, with additional 2mg doses at 5-minute intervals until pain relief is achieved 1, 3
• Alternative: Intravenous diamorphine or meperidine 2, 3
• Always administer with antiemetics to prevent nausea and vomiting 2, 1
• Adequate analgesia is essential—it reduces sympathetic activation and cardiac workload 1

Diagnostic Assessment

ECG

• Obtain 12-lead ECG within 10 minutes of arrival to emergency department 1
• Look for ST-segment elevation ≥1mm in contiguous leads or new left bundle branch block, which indicates need for immediate reperfusion therapy 1
• ECG should not delay aspirin administration 1

Monitoring

• Establish continuous cardiac monitoring immediately to detect life-threatening arrhythmias 1
• Arrhythmias are most common in the first 24 hours 1
• Emergency resuscitation equipment and defibrillator must be immediately available 2, 1

Reperfusion Therapy (The Critical Intervention)

All patients with ST-elevation MI or new LBBB require immediate reperfusion therapy (in the absence of contraindications) 1:

Thrombolytic Therapy (Fibrinolysis)

• Greatest benefit when initiated within 6 hours of symptom onset, with maximum benefit in the first hour 1
• Common agents: Tissue plasminogen activator (alteplase), streptokinase, urokinase 4, 3
• Heparin administration may be beneficial, particularly with tissue plasminogen activator 1

Primary Percutaneous Coronary Intervention (PCI)

• Alternative to thrombolysis if performed in timely fashion by skilled personnel with access to emergency CABG 1
• Preferred in high-risk patients with signs of shock, pulmonary congestion, heart rate >100 bpm, systolic BP <100 mmHg 2

Critical Pitfalls to Avoid

Timing Errors

• Never delay ECG assessment beyond 10 minutes of patient arrival 1
• Do not withhold aspirin while waiting for definitive diagnosis 1
• Avoid delaying reperfusion therapy—benefit is time-dependent with greatest advantage in the first hour 1

Medication Errors

• Do not administer thrombolytics to patients without ST-elevation or with contraindications (active bleeding, prior stroke/TIA, recent surgery) 1, 5
• Do not give nitroglycerin if systolic BP <90mmHg or heart rate abnormalities are present 1

Pain Management Errors

• Failing to provide adequate analgesia increases sympathetic activation and worsens cardiac workload 1
• Always use intravenous opioids, not oral analgesics, for acute MI 1

Special Populations

Elderly Patients (>75 years)

• Increased risk of fatal and intracranial bleeding with thrombolytic therapy 5
• Consider risk-benefit carefully; may still benefit in high-risk situations (diabetes, prior MI) 5

Low Body Weight (<60 kg)

• Increased bleeding risk with standard dosing 5
• Consider dose adjustment for antiplatelet agents 5

Patients with Prior Stroke/TIA

• Thrombolytic therapy is contraindicated in patients with history of stroke or TIA 5

Emergency Medical Services Role

• All patients with chest pain require emergency response with a vehicle containing a defibrillator and staff trained in its use 2
• Using 911/EMS almost always decreases delays in initiation of definitive care 2
• Ambulance services should have defibrillators and trained personnel for advanced cardiac life support 2

Additional Supportive Measures

• Provide reassurance—anxiety is a natural response; tranquilizers may be considered if necessary 1
• Have emergency drugs available: Adrenaline, atropine, lignocaine, frusemide, naloxone 2
• For large anterior MI or LV mural thrombus, early intravenous heparin may reduce stroke risk 1