Initiate medical therapy that may improve cardiac symptoms and reduce cardiovascular mortality, while preparations are made for reperfusion therapy.

Medical therapy should be initiated while preparations are made for reperfusion therapy. Medications that may be given at this time include the following:

1. Non-coated aspirin:



• All patients should chew 160 mg to 325 mg of aspirin within 10 minutes of presentation.
• Patients should be given aspirin, even if they are receiving anticoagulation (e.g., warfarin) or antiplatelet agents (e.g., aspirin or clopidogrel) at time of presentation.
• If a patient is unable to take aspirin by mouth because of nausea, vomiting, or other gastrointestinal disorders, 325 mg may be given as a suppository.
• Contraindications to aspirin include a documented allergy to salicylates, active bleeding, active peptic ulcer disease or gastrointestinal intolerance.
• Patients who have an allergy to aspirin and no contraindication to antiplatelet therapy should be given clopidogrel, ticlopidine, or dypyridamole.


2. Beta-blockers:



• Metoprolol 5 mg IV for up to 3 doses or atenolol 5 mg to 10 mg IV should be given within 12 hours of presentation.
• Oral beta-blockers should be started at the time the intravenous beta-blocker is given.
• Relative contraindications to beta-blockers, include: heart rate <60 beats per minute (bpm), systolic blood pressure <100 mm Hg, moderate or severe CHF, signs of peripheral hypoperfusion, PR interval >0.24 seconds on the ECG, second or third degree atrioventricular (AV) block, severe COPD, and history of asthma.
• Diabetes should not be considered a contraindication to beta-blocker therapy in the setting of an AMI.


3. Intravenous unfractionated heparin:



• Unfractionated heparin should be initiated in all patients receiving alteplase, reteplase, or tenectaplase or referred for emergent revascularization. Heparin may be started at 60 U/kg (maximum 4000 U) IV bolus, followed by an infusion of 12 U/kg/hr infusion (maximum 1000 U/hr) with a goal APTT of 50 to 70 seconds. The use of heparin should be continued for 48 hours and then reassessed.
• Patients receiving streptokinase who are at high risk for systemic emboli (i.e., who have a large or anterior wall MI, previous embolus, or known left ventricular (LV) thrombus) should be started on intravenous heparin only if the APTT is <2 times control 6 hours from the initiation of streptokinase. Heparin may then be given with a goal APTT of 1.5 to 2.0 times control.


4. Nitroglycerin:



• Patients presenting with symptoms consistent with a MI and ECG changes suggestive of an STEMI, may be given nitroglycerin 0.3 mg to 0.4 mg sublingually during the initial evaluation. Vasospastic angina may respond to sublinqual nitroglycerin. The administration of sublingual nitroglycerin should not delay reperfusion therapy.
• Intravenous nitroglycerin should be considered for 24 to 48 hours in patients with a large, anterior wall MI, persistent ischemia, CHF, or hypertension.
• Nitrates should be avoided in patients with evidence for a right ventricular infarction.
• Contraindications to nitrates include the use of sildenafil within 24 hours of presentation, hypotension (systolic blood pressure <90 mm Hg), or significant bradycardia (i.e., heart rate <50 bpm).


5. Oral angiotensin-converting enzyme inhibitors (ACE-inhibitor):



• Oral ACE-inhibitor should be considered in all patients within 24 hours of a MI, but especially in those patients with an acute anterior wall MI, CHF from systolic dysfunction, or left ventricular ejection fraction (LVEF) <0.40.
• ACE-inhibitor should be avoided in patients with hypotension or known contraindication, including: history of ACE-inhibitor induced angioedema, hyperkalemia, acute renal failure, and bilateral renal artery stenosis.


6. Analgesics:



• Because of increased sympathetic stimulation associated with pain from an AMI, patients should be offered analgesics, such as morphine sulfate 2 mg to 4 mg IV as needed (PRN). Per ACC/AHA AMI (1996) recommendations, analgesia should not be withheld from patients to evaluate the efficacy of reperfusion therapy.
• Routine use of anxiolytics, such as diazepam, is usually not necessary.

Although the focus in initial management of AMI is on reperfusion of the occluded artery, studies have shown that initial medical management can also have an impact on patient outcomes.