Why is primary percutaneous coronary intervention (PCI) preferred over fibrinolytic therapy for an adult patient with ST‑segment‑elevation myocardial infarction (STEMI)?

Why Primary PCI is Preferred Over Fibrinolytic Therapy in STEMI

Primary percutaneous coronary intervention (PCI) is superior to fibrinolytic therapy because it produces higher rates of complete coronary artery patency (TIMI 3 flow in 70-90% vs. lower with fibrinolysis), significantly reduces mortality, reinfarction, recurrent ischemia, and intracranial hemorrhage, while allowing immediate assessment of coronary anatomy and hemodynamic status. 1

Superior Clinical Outcomes with Primary PCI

Primary PCI delivers better outcomes across multiple critical endpoints when performed by experienced operators within appropriate time windows:

• Mortality reduction: Primary PCI demonstrates lower death rates compared to fibrinolysis, with the greatest survival benefit observed in high-risk patients 1
• Complete reperfusion: Primary PCI achieves TIMI 3 flow (near-normal coronary perfusion) in 70-90% of patients, substantially higher than fibrinolytic therapy 1
• Reduced reinfarction: Lower rates of recurrent myocardial infarction occur with mechanical reperfusion 1
• Less recurrent ischemia: Primary PCI reduces the need for emergency repeat revascularization procedures 1

Critical Safety Advantage: Intracranial Hemorrhage

The most compelling safety advantage of primary PCI is the dramatically lower risk of intracranial hemorrhage compared to fibrinolytic therapy. 1 This is particularly important in:

• Elderly patients (≥75 years), who have substantially elevated stroke risk with fibrinolysis 2
• Patients with any contraindications to fibrinolysis, where primary PCI should be performed regardless of time delay 1
• High-risk patients who would otherwise face increased bleeding complications 1

Time-Dependent Superiority

The benefit of primary PCI over fibrinolysis is time-dependent and requires adherence to specific benchmarks:

• Primary PCI is preferred when it can be performed within 120 minutes from first medical contact (FMC) to device time 1, 2
• For patients presenting directly to PCI-capable centers, the target is ≤90 minutes from FMC to device 1, 2
• Recent data from China (2025) identified 119.51 minutes as the critical threshold beyond which primary PCI loses its mortality advantage over immediate fibrinolysis 3
• When anticipated PCI delays exceed 120 minutes, fibrinolytic therapy becomes the preferred strategy if it can be delivered within 10-30 minutes 1, 2

Additional Clinical Benefits

Primary PCI provides several practical advantages beyond reperfusion:

• Immediate diagnostic information: Coronary angiography reveals the extent of disease, identifies patients with spontaneous reperfusion, coronary vasospasm, or dissection 1
• Earlier hospital discharge: Successful PCI allows faster recovery and resumption of daily activities 1
• Reduced complications: Fewer complications from prolonged ischemia or failed fibrinolysis 1
• Broader applicability: Fewer contraindications compared to fibrinolytic therapy 1

Absolute Indications for Primary PCI Regardless of Time

Primary PCI must be performed irrespective of time delay in these high-risk scenarios:

• Cardiogenic shock or acute severe heart failure at any time from MI onset 1, 2
• Contraindications to fibrinolytic therapy with ischemic symptoms <12 hours 1
• Resuscitated cardiac arrest with ST-elevation on post-resuscitation ECG 2

Important Caveats and System Requirements

The superiority of primary PCI depends critically on several factors:

• Operator and center experience: Outcomes are worse with low-volume hospitals and operators 1
• 24/7 availability: PCI-capable centers must provide around-the-clock service without delay 1, 2
• Experienced interventional team: High-volume, well-equipped centers with skilled support staff are essential 1
• Direct catheterization laboratory transfer: Patients should bypass the emergency department 1, 2

When Fibrinolysis Becomes Preferable

Despite the general superiority of primary PCI, fibrinolytic therapy is the better choice when:

• Anticipated FMC-to-device time exceeds 120 minutes and fibrinolysis can be delivered within 10-30 minutes 1, 2
• Very early presentation (<2 hours from symptom onset) with prolonged transfer times, where the time advantage of immediate fibrinolysis may offset PCI's mechanical superiority 1, 3
• Prehospital setting with long transport times to PCI-capable facilities, particularly in rural or resource-limited areas 1, 4

Subgroup Considerations

The threshold for PCI superiority varies by patient characteristics:

• Older patients (>75 years) have lower equipoise thresholds, meaning they benefit from primary PCI even with shorter delays 3
• Anterior MI patients show greater benefit from timely primary PCI 3
• Higher Killip class (heart failure severity) patients have lower time thresholds for PCI benefit 3

Technical Superiority

Primary PCI offers technical advantages:

• Radial artery access should be the default approach, reducing bleeding and vascular complications 2, 5
• Drug-eluting stents are the standard of care 2, 5
• Routine thrombus aspiration is contraindicated based on current evidence 2