What other medications are used in first aid for myocardial infarction (MI) besides aspirin?

Medications Used in First Aid for Myocardial Infarction Beyond Aspirin

In addition to aspirin, first aid management of suspected MI should include nitroglycerin for symptom relief and oxygen if hypoxemic, with beta-blockers and heparin initiated early in the hospital setting. 1

Immediate First Aid Medications (Pre-Hospital/Emergency Department)

Nitroglycerin

• Sublingual nitroglycerin or nitroglycerin spray should be administered for immediate relief of chest pain in patients with suspected MI 2
• Nitroglycerin achieves benefit by producing nitric oxide, causing vasodilation and increasing blood flow to the ischemic myocardium 3
• Avoid nitroglycerin in patients with hypotension, bradycardia, or excessive tachycardia 2, 1
• Nitroglycerin should not be used as a substitute for narcotic analgesics, which are often required for pain control 2

Oxygen Therapy

• Oxygen should be administered via nasal prongs as part of initial emergency management 1
• Current evidence does not support routine supplemental oxygen use by first aid providers in all cases 2

Narcotic Analgesics

• Appropriate analgesics should be used to minimize pain and anxiety in the first 24 hours 2
• These are often required and should not be replaced by nitroglycerin alone 2

Early Hospital Medications (First 24 Hours)

Beta-Blockers

• Early intravenous beta-blocker therapy followed by oral therapy should be administered if no contraindications exist (absence of hypotension, bradycardia, heart failure) 2, 1
• Beta-blockers reduce morbidity and mortality in both the pre-thrombolytic and thrombolytic eras 2
• Beta-blocker therapy should be initiated regardless of whether reperfusion therapy was given 2
• Continue oral beta-blocker therapy for at least 6 weeks 2, 1

Anticoagulation (Heparin)

• Intravenous heparin should be administered, particularly for patients with large anterior MI who are at high risk for left ventricular mural thrombus and embolic stroke 2, 1
• For patients receiving alteplase (tPA), intravenous heparin should be given for an additional 48 hours 2
• High-dose intravenous heparin is recommended when primary PCI is performed 2
• For patients receiving enoxaparin in STEMI, dosing is 30 mg IV bolus plus 1 mg/kg subcutaneous (for patients <75 years), followed by 1 mg/kg subcutaneous every 12 hours 4

Intravenous Nitroglycerin

• Intravenous nitroglycerin should be infused for 24-48 hours in patients without hypotension, bradycardia, or excessive tachycardia 2, 1
• IV nitroglycerin can be titrated successfully with frequent measurement of heart rate and blood pressure, unlike oral nitrate preparations 2
• Despite absence of definitive outcome data, this remains reasonable practice 2

ACE Inhibitors

• ACE inhibitors should be considered, particularly for patients with anterior MI or left ventricular dysfunction 1
• ACE inhibitors are indicated in all patients with CAD who also have diabetes and/or LV systolic dysfunction 2

Medications to Avoid

Calcium Channel Blockers

• Calcium channel blockers have not been shown to reduce mortality in acute MI and may be harmful in certain patients 2
• Short-acting dihydropyridine calcium antagonists should be avoided 2

Prophylactic Antiarrhythmics

• Prophylactic antiarrhythmic agents in the first 24 hours are not recommended 2
• However, atropine, lidocaine, transcutaneous pacing patches, defibrillator, and epinephrine should be immediately available 2

Routine IV Magnesium

• Magnesium sulfate should only be given as needed to replete magnesium deficits for 24 hours, not routinely 2

Alternative Antiplatelet Agents

Clopidogrel

• Clopidogrel is indicated when aspirin is absolutely contraindicated 2
• In acute coronary syndromes, clopidogrel added to aspirin reduces risk of vascular events but increases bleeding risk 5
• Clopidogrel requires conversion to active metabolite by CYP2C19; consider alternative P2Y12 inhibitor in CYP2C19 poor metabolizers 6

Critical Timing Considerations

• Early administration of aspirin (prehospital or within first hours) reduces cardiovascular mortality at 7 days (RR 0.37) and 30 days (RR 0.45) compared to delayed administration 2
• The greatest benefit from thrombolysis occurs within the first hour of symptom onset, saving 35 lives per 1000 patients treated 1
• Continuous cardiac monitoring with emergency resuscitation equipment should be readily available, as reinfarction and death occur most frequently within the first 24 hours 2, 1