Management of ST-Elevation Myocardial Infarction (STEMI)
Immediately administer 162-325 mg of non-enteric coated aspirin and proceed with urgent reperfusion therapy—primary PCI if achievable within 120 minutes of first medical contact, or fibrinolysis within 30 minutes if PCI cannot be performed in this timeframe. 1, 2, 3
Initial Assessment and Immediate Actions
Obtain a 12-lead ECG within 10 minutes of emergency department arrival for all patients with chest discomfort or STEMI symptoms. 1, 2 STEMI is confirmed by ST-segment elevation >0.1 mV in at least two contiguous precordial or adjacent limb leads, new left bundle branch block, or true posterior MI. 1
If the initial ECG is non-diagnostic but clinical suspicion remains high, perform serial ECGs at 5-10 minute intervals or use continuous 12-lead ST-segment monitoring. 1, 2
Administer aspirin 162-325 mg immediately upon first medical contact—this is non-negotiable for all STEMI patients. 1, 2, 3 Use non-enteric coated formulation for faster absorption. 2
Place the patient on continuous cardiac monitoring for arrhythmia detection. 3
Reperfusion Strategy: The Critical 120-Minute Decision
Primary PCI is the preferred reperfusion strategy if first medical contact-to-device time can be achieved within 120 minutes. 1, 2, 3 For high-risk patients presenting within 2 hours of symptom onset, the acceptable PCI-related delay shortens to 90 minutes. 2
If primary PCI cannot be performed within 120 minutes, immediately initiate fibrinolytic therapy within 30 minutes of hospital arrival using a fibrin-specific agent. 1, 2, 3 Tenecteplase is preferred as a single weight-adjusted IV bolus; reduce the dose by 50% in patients ≥75 years old to reduce stroke risk. 3
Critical caveat: Do not use prasugrel or fibrinolysis in patients with prior transient ischemic attack or stroke—these patients have substantially higher rates of intracranial hemorrhage (2.3% with prasugrel vs 0% with clopidogrel). 4
Transfer all patients receiving fibrinolysis to a PCI-capable center immediately after administration for angiography between 2-24 hours post-fibrinolysis. 3 This pharmacoinvasive approach is now standard of care. 5
Antithrombotic Therapy
For primary PCI, administer dual antiplatelet therapy with aspirin plus a potent P2Y12 inhibitor before the procedure. 1, 3
Prasugrel 60 mg loading dose is preferred over clopidogrel for patients undergoing primary PCI, provided they have no history of stroke/TIA and are not ≥75 years old. 3, 4 Prasugrel reduces the composite endpoint of cardiovascular death, nonfatal MI, or stroke compared to clopidogrel, driven predominantly by MI reduction. 4
Important dosing considerations for prasugrel:
- Patients <60 kg have increased bleeding risk; consider reducing maintenance dose to 5 mg daily (though this dose has not been prospectively studied). 4
- In patients ≥75 years, prasugrel is generally not recommended except in high-risk situations (diabetes or prior MI) where benefit may outweigh the increased risk of fatal and intracranial bleeding. 4
For fibrinolysis, use aspirin plus clopidogrel as the P2Y12 inhibitor of choice. 1
Anticoagulation: Use unfractionated heparin as weight-adjusted IV bolus followed by infusion for primary PCI. 3 If fibrinolytic therapy is administered, use enoxaparin IV followed by subcutaneous dosing. 3
Continue dual antiplatelet therapy for at least 12 months in patients receiving stents. 2, 4
Adjunctive Medical Therapy
Beta-blockers should be administered promptly unless contraindications exist (frank heart failure, hypotension, persistent tachycardia, bradycardia, or signs of low-output state). 5, 2, 3 Continue indefinitely in all eligible patients. 5
Morphine sulfate 2-4 mg IV with increments of 2-8 mg at 5-15 minute intervals for ongoing ischemic pain or pulmonary congestion. 2, 3
Oxygen supplementation only if arterial oxygen saturation <90%—routine oxygen administration is not beneficial. 2, 3
Avoid ibuprofen as it blocks the antiplatelet effects of aspirin. 5
Post-STEMI Medical Management
Initiate ACE inhibitors within 24 hours in all patients, particularly those with anterior MI, heart failure, or ejection fraction ≤0.40. 5, 2 Start with low-dose captopril (1-6.25 mg) unless systolic blood pressure <100 mmHg. 3
For patients intolerant of ACE inhibitors who have clinical or radiological signs of heart failure or LVEF <0.40, use ARBs. 5
Aldosterone blockade is indicated in patients without significant renal dysfunction (creatinine ≤2.5 mg/dL in men or ≤2.0 mg/dL in women) or hyperkalemia (potassium ≤5.0 mEq/L) who are already receiving therapeutic doses of an ACE inhibitor, have LVEF ≤0.40, and have either diabetes or heart failure. 5
High-intensity statin therapy should be started in all STEMI patients without contraindications. 2
Warfarin (INR 2.0-3.0) is indicated for patients with persistent or paroxysmal atrial fibrillation. 5 For aspirin-allergic patients with stent implanted receiving clopidogrel, maintain INR 2.0-3.0; without stent, target INR 2.5-3.5. 5
Management of Cardiogenic Shock
Emergency revascularization (PCI or CABG) is recommended regardless of time delay from MI onset for patients with cardiogenic shock. 5, 1, 2, 3 Primary PCI remains the preferred strategy over fibrinolytic therapy in shock. 3
Intra-aortic balloon counterpulsation is useful for patients with cardiogenic shock not quickly stabilized with pharmacological therapy. 1, 2, 3
For patients <75 years who develop shock within 36 hours of MI, early revascularization should be performed. 3 For patients ≥75 years with cardiogenic shock, emergency revascularization should still be considered, especially in those with good prior functional status. 2
Post-Discharge Care and Secondary Prevention
Cardiac rehabilitation programs are recommended for all STEMI patients, particularly those with multiple modifiable risk factors. 5 Patients should exercise for a minimum of 30 minutes, preferably daily but at least 3-4 times per week. 5
Smoking cessation is mandatory—provide counseling to patient and family, along with pharmacological therapy (nicotine replacement and bupropion) and formal smoking-cessation programs. 5
Routine echocardiography during hospital stay to assess LV and RV function, detect mechanical complications, and exclude LV thrombus. 1
Follow-up ECGs at 24 hours and hospital discharge to assess reperfusion success and infarct extent. 1
Critical Pitfalls to Avoid
Do not delay reperfusion therapy to wait for cardiac biomarker results—initiate treatment based on clinical presentation and ECG findings. 2
Do not start prasugrel in patients likely to undergo urgent CABG—when possible, discontinue prasugrel at least 7 days prior to any surgery due to substantial bleeding risk. 4
Do not perform delayed PCI of a totally occluded infarct artery >24 hours after STEMI in asymptomatic stable patients—this provides no benefit. 5
Do not discontinue dual antiplatelet therapy prematurely, particularly in the first few weeks after ACS, as this increases the risk of subsequent cardiovascular events including stent thrombosis. 4
Hormone therapy with estrogen plus progestin should not be given de novo to postmenopausal women after STEMI and should be discontinued in those already taking it. 5