What is the recommended acute management of a patient with an ST‑elevation myocardial infarction?

Acute Management of ST-Elevation Myocardial Infarction

Primary percutaneous coronary intervention (PCI) performed within 90–120 minutes of first medical contact is the definitive treatment for STEMI, and all other acute interventions exist solely to support this goal or serve as alternatives when PCI is unavailable. 1, 2

Immediate Actions (First 10 Minutes)

Diagnosis and Monitoring

• Obtain and interpret a 12-lead ECG within 10 minutes of first medical contact to confirm ST-elevation or STEMI-equivalent patterns (new left bundle branch block, isolated anterior ST-depression with aVR elevation, or hyperacute T-waves). 1, 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately. 1, 2
• Avoid routine supplemental oxygen unless oxygen saturation falls below 90%. 1, 2

Initial Pharmacotherapy

• Administer aspirin 150–325 mg orally (chewed, non-enteric) or 250–500 mg intravenously if the patient cannot swallow—this must occur immediately at first medical contact. 1, 2
• The aspirin dose of 162 mg may be as effective as 325 mg with lower bleeding risk, though either dose is acceptable. 3

Reperfusion Strategy Selection: The 120-Minute Rule

Primary PCI (Preferred Strategy)

Primary PCI is the preferred reperfusion method when it can be performed ≤120 minutes from STEMI diagnosis (or ≤90 minutes if presenting directly to a PCI-capable hospital). 1, 2

Transfer and Logistics

• Transfer the patient directly to the catheterization laboratory, bypassing the emergency department and intensive care unit—this is a Class I recommendation. 1, 2
• PCI-capable centers must provide 24/7, no-delay service with experienced operators. 1, 2
• Regional STEMI networks should coordinate Emergency Medical Services and hospitals with standardized protocols to minimize door-to-balloon time. 1, 2

Antithrombotic Regimen for Primary PCI

• Give a potent P2Y12 inhibitor before or at the time of PCI: prasugrel 60 mg loading dose or ticagrelor 180 mg loading dose (clopidogrel 600 mg only if prasugrel/ticagrelor are unavailable or contraindicated). 1, 2
• Administer unfractionated heparin 100 U/kg IV bolus (reduce to 60 U/kg if a GPIIb/IIIa inhibitor is used); enoxaparin or bivalirudin are acceptable alternatives. 1, 2
• Fondaparinux is contraindicated for primary PCI. 1, 2

Technical Standards During PCI

• Use routine radial arterial access to minimize bleeding complications. 2
• Implant drug-eluting stents as the default device. 2
• Routine thrombus aspiration and deferred stenting are contraindicated—they do not improve outcomes and may cause harm. 2

Fibrinolytic Strategy (When PCI Delay >120 Minutes)

If primary PCI cannot be performed within 120 minutes of diagnosis, initiate fibrinolytic therapy within 10–30 minutes in patients presenting within 12 hours of symptom onset and without contraindications. 1, 2, 4

Fibrinolytic Agent Selection and Dosing

• Use a fibrin-specific agent: tenecteplase (preferred, single weight-adjusted bolus 30–50 mg), alteplase, or reteplase. 1, 2, 4
• For patients ≥75 years old, reduce tenecteplase dose by 50% to minimize stroke risk. 2, 4
• Streptokinase 1.5 million units IV over 30–60 minutes is an alternative when fibrin-specific agents are unavailable, but never re-administer streptokinase (antibodies persist ≥10 years). 4

Adjunctive Therapy with Fibrinolysis

• Continue aspirin (oral or IV). 1, 2, 4
• Add clopidogrel 75 mg daily (300 mg loading dose if <75 years old)—prasugrel and ticagrelor are not recommended with fibrinolysis. 1, 2, 4
• Provide anticoagulation with enoxaparin (30 mg IV bolus followed by 1 mg/kg subcutaneous every 12 hours, with dose adjustment for age ≥75 years and renal insufficiency) or unfractionated heparin until revascularization or for up to 8 days of hospitalization. 1, 4

Post-Fibrinolysis Management Algorithm

• At 60–90 minutes after fibrinolysis, assess ST-segment resolution in the lead with greatest initial elevation: ≥50% resolution indicates success; <50% indicates failure. 1, 2, 4
• Immediate rescue PCI is indicated for failed fibrinolysis (<50% ST-resolution), hemodynamic instability, cardiogenic shock, sustained ventricular arrhythmias, or worsening ischemia. 1, 2, 4
• After successful fibrinolysis, perform angiography and PCI of the infarct-related artery within 2–24 hours—transfer all patients to a PCI-capable center immediately after fibrinolysis. 1, 2, 4

Mandatory Primary PCI Regardless of Time Delay

Primary PCI must be performed immediately, irrespective of time from symptom onset, in the following situations:

• Cardiogenic shock or acute severe heart failure at any time after symptom onset. 1, 2
• Contraindications to fibrinolytic therapy (active bleeding, recent stroke, terminal illness, aortic dissection). 1, 2
• Failed fibrinolysis (persistent symptoms or <50% ST-resolution at 60–90 minutes). 1, 2

In-Hospital Management (First 24 Hours and Beyond)

Monitoring

• Monitor all STEMI patients for at least 24 hours after reperfusion therapy with continuous telemetry. 1, 2
• Perform routine echocardiography during hospitalization to assess left ventricular and right ventricular function, detect mechanical complications, and exclude left ventricular thrombus. 1, 2

Dual Antiplatelet Therapy (DAPT)

• Continue aspirin 75–100 mg daily indefinitely. 1, 2
• Continue prasugrel 10 mg daily or ticagrelor 90 mg twice daily for 12 months after PCI unless there are contraindications such as excessive bleeding risk. 1, 2
• Add a proton pump inhibitor in patients at high risk of gastrointestinal bleeding. 1, 2

Evidence-Based Medical Therapy

• Start high-intensity statin therapy (atorvastatin 80 mg or rosuvastatin 40 mg) as early as possible with an LDL-C goal of <1.8 mmol/L (70 mg/dL) or ≥50% reduction if baseline LDL-C is 1.8–3.5 mmol/L. 1, 2
• Initiate oral beta-blockers in patients with heart failure and/or left ventricular ejection fraction <40% after stabilization—avoid intravenous beta-blockers in patients with hypotension, acute heart failure, or severe bradycardia. 1, 2
• Start ACE inhibitors within 24 hours in patients with heart failure, left ventricular systolic dysfunction, diabetes, or anterior infarction. 1, 2
• Add a mineralocorticoid receptor antagonist in patients with ejection fraction <40% and heart failure who are already receiving an ACE inhibitor and beta-blocker, provided there is no severe renal failure or hyperkalemia. 1

Management of Left Ventricular Dysfunction and Acute Heart Failure

• Administer loop diuretics (furosemide 20–40 mg IV with repeated doses as needed) in patients with pulmonary congestion and symptoms of fluid overload. 1
• Use intravenous nitrates in patients with symptomatic heart failure and systolic blood pressure >90 mmHg to improve symptoms and reduce congestion. 1
• Provide oxygen therapy in patients with pulmonary edema and oxygen saturation <90% to maintain saturation >95%. 1
• Consider non-invasive positive pressure ventilation (CPAP or BiPAP) in patients with respiratory distress (respiratory rate >25 breaths/min, oxygen saturation <90%) without hypotension. 1

Special Clinical Scenarios

Cardiac Arrest with STEMI

• Patients with resuscitated cardiac arrest and ST-elevation on post-resuscitation ECG should undergo immediate primary PCI. 1, 2
• Initiate targeted temperature management early in unresponsive patients after cardiac arrest; avoid pre-hospital cooling with large volumes of cold intravenous fluid. 1, 2

Late Presentation (>12 Hours)

• Routine PCI of an occluded infarct-related artery >48 hours after symptom onset is not indicated in asymptomatic patients. 1, 2
• PCI is warranted in patients with hemodynamic or electrical instability, or persistent symptoms, regardless of time delay. 1, 2

Active Gastrointestinal Bleeding

• Primary PCI is the only reperfusion option—fibrinolytic therapy is an absolute contraindication. 2
• Administer aspirin immediately despite active bleeding because its mortality benefit in STEMI supersedes bleeding risk. 2
• Use unfractionated heparin at a reduced dose (70–100 U/kg IV bolus) because of its short half-life and reversibility with protamine. 2
• Defer P2Y12 inhibitor loading until after diagnostic angiography confirms the need for PCI. 2

MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries)

• A substantial proportion of STEMI patients have no significant coronary stenosis on urgent angiography—additional diagnostic testing (cardiac MRI, intravascular imaging) is required to identify the underlying cause (spontaneous coronary artery dissection, vasospasm, myocarditis, takotsubo cardiomyopathy). 1, 2, 5
• This is particularly common in young patients, especially females. 5

Critical Pitfalls to Avoid

• Never delay reperfusion therapy to "stabilize" a patient with active bleeding or other comorbidities—the mortality risk from untreated STEMI exceeds that from procedural complications. 2
• Never withhold aspirin or P2Y12 inhibitors because of bleeding concerns after PCI—the immediate threat of stent thrombosis is greater than the manageable bleeding risk. 2
• Never assume typical atherosclerotic disease in young patients—failure to investigate secondary causes (SCAD, vasospasm, thrombophilia) can result in recurrent events. 5
• Never routinely stent spontaneous coronary artery dissection lesions—this can worsen the dissection; conservative management is often superior. 5
• Never re-administer streptokinase—antibodies persist for at least 10 years and cause allergic reactions and treatment failure. 4

Post-Discharge Management

• Continue DAPT for 12 months after PCI unless life-threatening bleeding occurs—premature discontinuation markedly raises the risk of stent thrombosis and mortality. 1, 2
• Enroll all patients in a cardiac rehabilitation program. 1, 2
• Provide smoking cessation counseling with pharmacological support (nicotine replacement, varenicline, or bupropion). 1, 2
• Repeat echocardiography at 6–8 weeks to reassess left ventricular function and guide long-term therapy. 5