What is the appropriate workup and initial treatment for a patient with suspected acute anterolateral ST‑segment elevation myocardial infarction?

Workup and Management of Anterolateral ST-Elevation

Obtain a 12-lead ECG within 10 minutes of first medical contact, give aspirin 150–325 mg immediately, and activate the catheterization laboratory for primary PCI if door-to-balloon time will be ≤120 minutes; otherwise, administer fibrinolytic therapy within 10 minutes of diagnosis. 1

Immediate Diagnostic Actions (First 10 Minutes)

• Record and interpret a 12-lead ECG within 10 minutes of first medical contact to confirm ST-elevation in anterolateral leads (V3–V6, I, aVL) or identify STEMI equivalents such as new left bundle branch block, hyperacute T-waves, or isolated anterior ST-depression with ST-elevation in aVR. 1, 2

• Initiate continuous ECG monitoring with defibrillator capability immediately, as life-threatening ventricular arrhythmias are common in acute STEMI. 1, 2

• Administer aspirin 150–325 mg orally (or 250–500 mg IV if unable to swallow) as soon as STEMI is suspected; this is the single most important initial pharmacologic intervention. 1, 2

• Avoid routine supplemental oxygen unless peripheral oxygen saturation is <90%; routine oxygen therapy does not improve outcomes and may be harmful. 1, 2

• Draw blood for high-sensitivity cardiac troponin, complete blood count, creatinine, electrolytes, glucose, lipid profile, and coagulation studies on arrival, but do not delay reperfusion therapy while awaiting results. 3

Reperfusion Strategy Selection (The 120-Minute Rule)

Primary PCI Strategy (Preferred)

• Primary PCI is the preferred reperfusion method when the anticipated first-medical-contact-to-device time is ≤120 minutes; for patients presenting directly to a PCI-capable hospital, the target is ≤90 minutes. 1, 2

• Transfer the patient directly to the catheterization laboratory, bypassing the emergency department, to eliminate unnecessary delays; PCI-capable centers must provide 24/7 service without delay. 1, 2

• Give a potent P2Y12 inhibitor before or at the time of PCI: prasugrel 60 mg loading dose (preferred) or ticagrelor 180 mg loading dose; use clopidogrel 600 mg only if the former 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, but fondaparinux is contraindicated for primary PCI. 1, 2

• Use radial arterial access and implant drug-eluting stents as the standard of care; routine thrombus aspiration and deferred stenting are contraindicated. 1

Fibrinolytic Strategy (When PCI Delay >120 Minutes)

• If primary PCI cannot be achieved within 120 minutes, administer fibrinolytic therapy within 10 minutes of STEMI diagnosis, preferably in the pre-hospital setting; target door-to-needle time ≤30 minutes. 1, 2

• Use a fibrin-specific thrombolytic agent: tenecteplase (preferred for single-bolus administration), alteplase, or reteplase; these reduce mortality by an additional 10 deaths per 1,000 patients compared with streptokinase. 4, 5

• Add clopidogrel 75 mg daily to aspirin (prasugrel and ticagrelor are not recommended with fibrinolysis); this combination reduces death, reinfarction, and stroke by approximately 9 events per 1,000 treated. 4

• Provide anticoagulation with enoxaparin (IV bolus followed by subcutaneous dosing, preferred) or unfractionated heparin (weight-adjusted IV bolus followed by 24–48 hour infusion targeting aPTT 50–70 seconds). 4

Post-Fibrinolysis Management

Reperfusion Assessment (60–90 Minutes)

• Obtain a repeat ECG 60–90 minutes after fibrinolytic administration and measure ST-segment resolution in the lead with the greatest initial ST-elevation; ≥50% resolution indicates successful reperfusion, while <50% indicates failure. 4

Rescue PCI Indications

• Perform immediate rescue PCI without delay if fibrinolysis fails (<50% ST-segment resolution at 60–90 minutes); rescue PCI reduces the composite of death or reinfarction from 16.8% to 10.8% and all-cause mortality from 10.7% to 6.9%. 4

• Emergency angiography and PCI are also indicated for hemodynamic instability, cardiogenic shock, sustained ventricular arrhythmias, worsening ischemia, or development of acute heart failure at any time after fibrinolysis. 4

Routine Angiography After Successful Fibrinolysis

• Transfer all patients immediately to a PCI-capable center after fibrinolysis and perform angiography with PCI of the infarct-related artery within 2–24 hours, even if reperfusion appears successful; approximately 30% will require rescue PCI. 4

Mandatory Primary PCI Regardless of Time Delay

• Cardiogenic shock or acute severe heart failure at any time after symptom onset mandates primary PCI, regardless of the elapsed time from first medical contact. 1

• Contraindications to fibrinolytic therapy (prior intracranial hemorrhage, active bleeding, recent stroke, severe uncontrolled hypertension >180/110 mmHg despite treatment) require primary PCI as the only reperfusion option. 1, 4

In-Hospital Management

Monitoring and Imaging

• Monitor all reperfused patients for at least 24 hours after therapy in a unit with continuous ECG monitoring and defibrillation capability. 1, 2

• Perform routine transthoracic echocardiography during hospitalization to assess left- and right-ventricular function, detect mechanical complications (ventricular septal rupture, papillary muscle rupture, free wall rupture), and exclude left-ventricular thrombus. 1

Pharmacotherapy

• Continue dual antiplatelet therapy (aspirin 75–100 mg daily plus prasugrel 10 mg daily or ticagrelor 90 mg twice daily) for 12 months unless the patient has a high bleeding risk. 1, 2

• Initiate high-intensity statin therapy (atorvastatin 80 mg or rosuvastatin 40 mg) as early as possible, targeting LDL-C <1.8 mmol/L (70 mg/dL) or a ≥50% reduction if baseline is 1.8–3.5 mmol/L. 1

• Start oral beta-blockers in patients with heart failure and/or left-ventricular ejection fraction <40% unless contraindicated (avoid IV beta-blockers in the acute phase). 1

• Initiate ACE inhibitors within 24 hours in patients with heart failure, left-ventricular systolic dysfunction, diabetes, or anterior infarction. 1

Critical Pitfalls to Avoid

• Do not delay reperfusion therapy to "stabilize" the patient or await troponin results; the ECG diagnosis of STEMI is sufficient to proceed immediately. 1, 2

• Do not confuse non-ischemic ST-elevation (hypercalcemia, early repolarization, pericarditis, left ventricular hypertrophy) with STEMI; correlate ECG findings with clinical presentation, but when in doubt, activate the catheterization laboratory. 6, 7

• Do not perform routine PCI of an occluded infarct-related artery >48 hours after symptom onset in asymptomatic, hemodynamically stable patients; late PCI does not improve outcomes. 1

• Do not combine fibrinolysis with immediate planned PCI (so-called "facilitated PCI"); this strategy increases mortality and bleeding without benefit. 4

• Do not re-administer streptokinase if it was used previously (antibodies persist ≥10 years); use a fibrin-specific agent or proceed to rescue PCI instead. 4