Acute Myocardial Infarction Management

Patient Selection and Treatment

The American College of Cardiology recommends the use of nitroglycerin for symptomatic relief of angina during myocardial infarction, with a starting dose of 5-10 μg/min and titration every 5-10 minutes to achieve desired hemodynamic and clinical responses, particularly in patients with right ventricular infarction and inferior wall infarction who require careful titration due to the risk of hypotension 1
The combination of nitroglycerin with beta-blockers may be well-tolerated and theoretically attractive, as suggested by the American College of Cardiology 1
Administer aspirin 160-325 mg (chewed) unless contraindicated, as part of the initial treatment for acute coronary syndrome, as recommended by the American Heart Association 2, 3, 4, 5, 6
Consider beta-blockers if no contraindications exist, to help manage tachycardia and chest pain, with a recommendation based on evidence from 2015 by the American Heart Association 7

The initial dose of nitroglycerin is 5-10 μg/min, with titration every 5-10 minutes to achieve desired responses, including control of clinical symptoms, reduction of mean arterial pressure, and increase in heart rate, with end points of titration including control of clinical symptoms, reduction of mean arterial pressure by 10% in normotensive patients or 30% in hypertensive patients, and increase in heart rate by >10 beats/min 1
Initial dose of sublingual nitroglycerin is 0.3-0.4 mg every 5 minutes up to 3 doses, and starting dose for IV nitroglycerin is 10 μg/min, with titration of 5-10 μg/min every 5-10 minutes, as recommended by the American College of Cardiology 8, 9, 1
Monitor blood pressure after each dose of nitroglycerin, and discontinue if systolic BP drops below 90 mmHg or 30 mmHg below baseline, as recommended by the American College of Cardiology and American Heart Association 9, 8

Nitroglycerin may reduce infarct size in some patients, and early treatment is associated with better outcomes, with a meta-analysis of 10 studies demonstrating that intravenous nitrates reduce mortality by 10-30% 1
Nitroglycerin may also decrease the susceptibility to ventricular fibrillation during acute myocardial ischemia and reperfusion, and a randomized trial of 310 patients showed improved hospital survival (mortality rate 14% vs 26%, p<0.01) limited to patients with anterior infarction 1

Prolonged infusion of nitroglycerin may result in relative tolerance to nitrates, and administration of atropine may be necessary in cases of severe hypotension or bradycardia, as recommended by the American College of Cardiology 1
Contraindications for sublingual nitroglycerin and nitrates include recent use of phosphodiesterase-5 inhibitors, systolic blood pressure <90 mmHg, severe bradycardia or tachycardia, and right ventricular infarction, as recommended by the American College of Cardiology and American Heart Association 4, 10, 9, 8, 11, 2, 12, 13, 3, 14, 5
Common side effects of sublingual nitroglycerin include headache, dizziness, and hypotension, according to the American College of Cardiology, and patients should sit while taking nitroglycerin to prevent falls due to dizziness, with caution exercised when standing up after taking nitroglycerin due to common side effects of dizziness and lightheadedness 10, 2, 12, 10, 4

For angina symptoms that are unimproved or worsening after 5 minutes of onset, call emergency services (9-1-1) immediately if nitroglycerin is not available, as recommended by the American Heart Association, and ambulance transport is associated with better outcomes for patients with angina symptoms, as emergency medical technicians can provide life-saving interventions if cardiac arrest occurs 2, 15
Immediate ECG monitoring and intravenous nitroglycerin may be administered in the hospital for persistent angina symptoms, with possible morphine administration for pain unrelieved by nitrates, as recommended by the American Heart Association, and use morphine sulfate (2-4 mg IV with increments of 2-8 mg repeated at 5-15 minute intervals) for ongoing ischemic pain unresponsive to other measures, based on guidelines from 2015 by the American Heart Association 16, 10, 7, 9, 6, 14, 1
Provide supplemental oxygen if oxygen saturation is <94%, as recommended by the American Heart Association, and obtain a 12-lead ECG immediately to assess for STEMI or other ischemic changes, and consider portable echocardiography if available, as recommended by the American College of Cardiology and American Heart Association 6, 3, 9
Consider early IV β-blocker therapy followed by oral therapy, and coronary angiography with revascularization may be considered for persistent symptoms, as recommended by the American College of Cardiology and American Heart Association 5, 1

Long-term preventive medications such as beta-blockers, calcium channel blockers, or long-acting nitrates may be considered for optimal angina prevention, as recommended by the American College of Cardiology 10, 17
The American College of Cardiology advises against taking sildenafil (Viagra) or similar medications if nitroglycerin may be needed soon, due to potential adverse interactions 16, 10