What is the recommended treatment for acute ST-elevation myocardial infarction (STEMI) using Primary Percutaneous Coronary Intervention (PCI)?

Primary PCI for STEMI

Primary percutaneous coronary intervention (PCI) is the preferred reperfusion treatment for acute ST-elevation myocardial infarction when performed by an experienced team within 90-120 minutes of first medical contact. 1, 2

Time-Critical Decision Algorithm

When to Choose Primary PCI:

• First medical contact-to-balloon time ≤90 minutes at PCI-capable centers (Class I-A recommendation) 1, 2
• First medical contact-to-balloon time ≤120 minutes with interhospital transfer (Class I-B recommendation) 1, 2
• Patients presenting within 2 hours of symptom onset with large infarct and low bleeding risk should receive primary PCI within 90 minutes 1
• Any patient in cardiogenic shock regardless of time delays (Class I-B recommendation) 1, 2
• Patients with contraindications to fibrinolytic therapy irrespective of time delay (Class I-B recommendation) 1, 2

When to Choose Fibrinolytic Therapy Instead:

• If anticipated door-to-balloon time exceeds door-to-needle time by more than 60 minutes, particularly when symptom duration is <3 hours 1, 3, 2
• If primary PCI cannot be performed within 120 minutes of first medical contact 3, 2, 4

Essential Requirements for Primary PCI

Team and Facility Requirements:

• Experienced interventional cardiologists with skilled supporting staff 1
• Established 24-hour/7-day interventional cardiology program 1
• High-volume centers demonstrate lower mortality rates 1
• Low-volume centers show mortality with primary PCI similar to fibrinolytic therapy (6.2% vs 5.9%) 1

Adjunctive Pharmacotherapy

Antiplatelet Therapy:

• Aspirin 150-325 mg orally (chewable) or IV immediately 1, 2, 5
• Clopidogrel loading dose if age <75 years (Class I-B); if age ≥75 years start with maintenance dose (Class IIa-B) 1
• Potent P2Y12 inhibitors (prasugrel 60 mg or ticagrelor) preferred over clopidogrel at time of PCI 5

Anticoagulation:

• Unfractionated heparin IV bolus 60-100 U/kg (60 U/kg if GPIIb/IIIa inhibitors used) 2, 5
• Continue anticoagulation until revascularization or up to 8 days 3

Technical Approach

Procedural Standards:

• Radial access preferred over femoral access 5
• Drug-eluting stents as standard of care 5
• Routine stent implantation decreases target vessel revascularization but does not significantly reduce death or reinfarction compared to balloon angioplasty alone 1
• Direct transport to catheterization laboratory, bypassing emergency department when possible 5

Rescue PCI After Failed Fibrinolysis

Indications (Class IIa-A):

• Failed fibrinolysis in patients with large infarcts if performed within 12 hours of symptom onset 1
• <50% ST-segment resolution 60-90 minutes after fibrinolysis initiation 1, 3
• Hemodynamic or electrical instability 2
• Persistent ischemic symptoms 1

Evidence: Rescue PCI shows significantly higher event-free survival at 6 months compared to repeat fibrinolysis or conservative treatment, though at increased risk of stroke and bleeding 1

Transfer Strategy for Non-PCI Hospitals

Transfer Protocol:

• Time from first hospital door to balloon inflation in second hospital should be <90 minutes 1
• Direct EMS transport to PCI facility results in median symptom-onset-to-needle time of 186 minutes versus 305 minutes for ED-transfer-PCI route 6
• The DANAMI-2 trial showed significant reduction in combined endpoint of death, reinfarction, and stroke (14.2% to 8.5%, p<0.002) with routine transfer for primary PCI versus in-hospital thrombolysis 1

Special Populations

High-Risk Scenarios Requiring Primary PCI:

• Cardiogenic shock (Class I-B) 1, 5
• Severe congestive heart failure 1
• Cardiac arrest with ST-elevation on post-resuscitation ECG 5
• Age <75 years with shock within 36 hours who have severe multivessel or left main disease, if revascularization can be performed within 18 hours of shock 5

Critical Pitfalls to Avoid

Time-Related Errors:

• Never delay ECG acquisition beyond 10 minutes of first medical contact 2, 5
• Do not wait for cardiac biomarker results before making transfer decisions 2
• Mortality increases significantly with each 15-minute delay in door-to-TIMI-3 flow time 1
• Each 30-minute delay from symptom onset to balloon inflation increases 1-year mortality (relative risk 1.08, p=0.04) 1

Strategy Selection Errors:

• Do not choose primary PCI over fibrinolysis when door-to-balloon time will exceed door-to-needle time by >60 minutes in patients presenting <3 hours from symptom onset 1
• Facilitated PCI (full-dose or half-dose lytic therapy before planned PCI) is NOT recommended - shows no mortality benefit but increased bleeding complications 1
• Do not perform primary PCI at low-volume centers when fibrinolysis would be equally effective 1

Post-Procedure Management:

• Continue DAPT for 12 months after PCI unless contraindications exist 5
• Initiate high-intensity statin therapy as early as possible 2, 5
• Start beta-blockers in patients with heart failure and/or LVEF <40% 5