What is the management approach for a patient presenting with ST-elevation myocardial infarction (STEMI)?

STEMI Management

Primary PCI is the preferred reperfusion strategy and must be performed within 90 minutes of first medical contact if presenting to a PCI-capable hospital, or within 120 minutes if transfer is required; if these time targets cannot be met, fibrinolytic therapy should be initiated within 30 minutes of STEMI diagnosis. 1, 2

Immediate Actions Upon First Medical Contact

• Administer aspirin 162-325 mg (chewable, non-enteric coated) immediately upon first medical contact, followed by maintenance dose of 75-100 mg daily indefinitely 1, 3, 4
• Obtain and interpret 12-lead ECG within 10 minutes of first medical contact 1, 3, 4
• STEMI diagnostic criteria: ST-segment elevation ≥0.1 mV (1 mm) in at least two contiguous precordial or adjacent limb leads, new or presumed new left bundle branch block, or true posterior MI 1, 3, 4
• If initial ECG is non-diagnostic but clinical suspicion remains high, perform serial ECGs at 5-10 minute intervals 3

Reperfusion Strategy Selection Algorithm

The critical decision point is whether primary PCI can be achieved within the appropriate time window from STEMI diagnosis:

Choose Primary PCI if:

• First medical contact-to-device time ≤90 minutes when presenting to PCI-capable hospital 1, 2
• First medical contact-to-device time ≤120 minutes when transfer is required 1, 2, 3
• Patient presents with cardiogenic shock or severe heart failure (regardless of time delay) 1
• Patient has contraindications to fibrinolysis 1

Choose Fibrinolytic Therapy if:

• Primary PCI cannot be performed within 120 minutes of STEMI diagnosis 1, 2
• Patient presents within 3 hours of symptom onset and PCI is not readily available 1
• Initiate fibrinolysis within 10 minutes of STEMI diagnosis, preferably in the pre-hospital setting 1

Critical Pitfall: Do NOT perform routine immediate PCI after successful fibrinolysis—this strategy increases bleeding, recurrent ischemia, and death without benefit 2, 5

Pre-Hospital and Transfer Logistics

• Emergency Medical Services should bypass the emergency department and transport patients directly to the cardiac catheterization laboratory 1, 6, 7
• Pre-hospital ECG diagnosis and catheterization laboratory activation by EMS significantly reduces door-to-balloon time by approximately 27 minutes 6, 7
• Transfer all patients to PCI-capable centers immediately after fibrinolysis for angiography and potential PCI 1

Antithrombotic Therapy

For Primary PCI:

• Aspirin 162-325 mg loading dose (already given), then 75-100 mg daily 1, 3, 4
• Potent P2Y12 inhibitor (prasugrel or ticagrelor preferred over clopidogrel) given before or at the time of PCI 1, 4
• Anticoagulation with unfractionated heparin (enoxaparin or bivalirudin are alternatives) 1
• Fondaparinux is NOT recommended for primary PCI 1

For Fibrinolytic Therapy:

• Fibrin-specific agent: tenecteplase, alteplase, or reteplase 1
• Half-dose tenecteplase should be considered in patients ≥75 years of age 1
• Aspirin oral or IV 1
• Clopidogrel (the P2Y12 inhibitor of choice with fibrinolysis) 1
• Anticoagulation: Enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin) until revascularization or for hospital stay up to 8 days 1

Important Caveat: After fibrinolysis, switch from clopidogrel to prasugrel/ticagrelor may be considered 48 hours later if patient underwent PCI 1

Post-Fibrinolysis Invasive Strategy

Following fibrinolysis, patients require angiography according to this algorithm:

• Emergency angiography and PCI immediately if heart failure/cardiogenic shock develops 1
• Rescue PCI immediately when fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes) or with hemodynamic/electrical instability 1
• Routine angiography and PCI between 2-24 hours after successful fibrinolysis 1
• Emergency angiography for recurrent ischemia or evidence of reocclusion 1

Technical Aspects of Primary PCI

• Radial access is preferred over femoral access 1
• Drug-eluting stents are standard of care 1
• Routine thrombus aspiration is contraindicated 1
• Treatment of non-infarct-related artery severe stenosis should be considered before hospital discharge (either during index PCI or staged) 1
• In cardiogenic shock, non-infarct-related artery PCI should be considered during the index procedure 1

Contraindications to Fibrinolytic Therapy

Absolute contraindications (from FDA label for tenecteplase): 5

• Active internal bleeding
• History of cerebrovascular accident
• Intracranial or intraspinal surgery or trauma within 2 months
• Intracranial neoplasm, arteriovenous malformation, or aneurysm
• Known bleeding diathesis
• Severe uncontrolled hypertension

Management of Cardiogenic Shock

• Emergency revascularization (PCI or CABG) regardless of time delay from MI onset 3
• Intra-aortic balloon counterpulsation for patients not quickly stabilized with pharmacological therapy 3
• Primary PCI strategy for cardiac arrest patients with ST-elevation on post-resuscitation ECG 1, 2

Post-STEMI Medical Management

• ACE inhibitors within 24 hours in all patients, particularly those with anterior MI, heart failure, or ejection fraction ≤0.40 3
• Oral beta-blockers indefinitely in all eligible patients without high-risk features (avoid in patients with signs of heart failure, hemodynamic instability, or heart block) 1, 3
• High-intensity statin therapy immediately with target LDL-C <70 mg/dL or ≥50% reduction from baseline 2, 4
• Dual antiplatelet therapy (DAPT) for 12 months with aspirin plus prasugrel or ticagrelor 1, 4

In-Hospital Assessment

• Routine echocardiography during hospital stay to assess LV and RV function, detect mechanical complications, and exclude LV thrombus 1
• Targeted temperature management is indicated early after resuscitation of cardiac arrest patients who remain unresponsive 1

Emergency CABG Indications

Emergency or urgent CABG should be performed for: 2

• Failed PCI with persistent pain or hemodynamic instability in patients with suitable coronary anatomy
• Persistent or recurrent ischemia refractory to medical therapy with significant myocardium at risk
• Mechanical complications (ventricular septal rupture, papillary muscle rupture) requiring urgent surgical repair with concomitant CABG

Special Populations

• Women receive equal benefit from reperfusion and other STEMI therapies as men and must be managed equally 1
• Elderly patients ≥75 years should receive half-dose tenecteplase if fibrinolysis is chosen 1

Secondary Prevention

• Smoking cessation with repeated advice, follow-up support, nicotine replacement therapies, varenicline, or bupropion 1, 4
• Cardiac rehabilitation program participation is strongly recommended 1, 4

Critical Time Targets Summary

• ECG acquisition and interpretation: ≤10 minutes from first medical contact 1, 3
• Fibrinolysis initiation: ≤30 minutes from STEMI diagnosis 1
• Primary PCI (door-to-balloon): ≤90 minutes if presenting to PCI-capable hospital 1, 2
• Primary PCI with transfer: ≤120 minutes from first medical contact 1, 2, 3