In a patient with acute chest pain suggestive of myocardial infarction and no contraindications (no aspirin allergy, no active bleeding, systolic BP ≥90 mm Hg, no recent phosphodiesterase‑5 inhibitor use), what medications should be given immediately?

Immediate Medications for Acute Myocardial Infarction

Give 162–325 mg non-enteric aspirin (chewed immediately), nitroglycerin up to 3 doses at 3–5 minute intervals, and morphine if chest pain persists despite nitroglycerin. 1

Aspirin Administration

• Administer 162–325 mg non-enteric aspirin immediately, instructing the patient to chew the tablet thoroughly before swallowing. 1, 2
• The chewing technique accelerates buccal absorption and shortens time to antiplatelet effect compared to swallowing whole tablets. 1, 2, 3
• Non-enteric formulations provide more rapid absorption than enteric-coated preparations; enteric-coated aspirin significantly delays absorption during the critical early phase when rapid action is most needed. 1, 2
• The 162 mg dose achieves plasma concentrations required to maximally inhibit platelet aggregation within approximately 30 minutes. 3
• Higher doses (325 mg) do not provide proportionally greater mortality benefit but may increase bleeding risk. 4

Nitroglycerin Protocol

• Administer up to 3 nitroglycerin doses (tablets or spray) at 3–5 minute intervals for ongoing chest pain. 1
• Nitroglycerin is absolutely contraindicated when systolic blood pressure is <90 mm Hg or ≥30 mm Hg below baseline. 1
• Nitroglycerin is contraindicated when patients have taken a phosphodiesterase-5 inhibitor within 24 hours (48 hours for tadalafil). 1
• Use extreme caution in patients with inferior wall STEMI due to potential right ventricular involvement; obtain a right-sided ECG to evaluate for RV infarction before administering nitrates. 1

Morphine for Refractory Pain

• Administer morphine when chest discomfort is unresponsive to nitroglycerin in STEMI patients. 1
• Use morphine with caution in unstable angina/NSTEMI due to an association with increased mortality in large registry data. 1

Beta-Blocker Consideration

• Administer a beta-blocker within 24 hours after hospital arrival unless contraindications exist. 1
• Beta-blocker contraindications include: bradycardia (heart rate <60 beats/min), heart failure, second- or third-degree heart block without pacemaker, shock, or beta-blocker allergy. 1
• Beta-blockers reduce ventricular arrhythmias, recurrent ischemia, reinfarction, and if given early enough, infarct size and short-term mortality. 1

Oxygen Therapy

• Administer oxygen only if the patient is dyspneic, hypoxemic, or has obvious signs of heart failure; titrate to maintain oxyhemoglobin saturation ≥94%. 1
• There is insufficient evidence to support routine oxygen use in uncomplicated acute coronary syndromes. 1

Common Pitfalls to Avoid

• Do not delay aspirin administration to obtain physician consultation if the patient meets criteria and has no contraindications, as time to treatment directly correlates with mortality reduction. 2
• Do not use enteric-coated aspirin formulations for acute presentation, as they significantly delay absorption. 1, 2
• Do not administer nitrates to patients who have taken phosphodiesterase-5 inhibitors within the specified timeframe (24–48 hours). 1
• Do not give beta-blockers to patients with active heart failure, bradycardia, or heart block without first addressing these conditions. 1