What is the benefit of Percutaneous Coronary Intervention (PCI) in a patient with ST-Elevation Myocardial Infarction (STEMI) presenting more than 12 hours after symptom onset?

PCI in STEMI After 12 Hours: Evidence-Based Recommendations

Primary PCI is reasonable and beneficial for STEMI patients presenting 12-24 hours after symptom onset, particularly when there is evidence of ongoing ischemia, hemodynamic instability, or a large area of myocardium at risk. 1

Time-Based Treatment Strategy

12-24 Hours After Symptom Onset

Primary PCI should be performed if any of the following are present:

• Ongoing ischemic symptoms (persistent chest pain despite medical therapy) 1
• ECG evidence of ongoing ischemia (persistent ST-segment elevation or <50% resolution of ST segments) 1
• Hemodynamic instability (hypotension, signs of shock, or cardiogenic shock) 1
• Severe heart failure (Killip class ≥3) or pulmonary edema 1
• Life-threatening arrhythmias (ventricular tachycardia or fibrillation) 1
• Large area of myocardium at risk (extensive ST elevation in multiple leads) 1, 2

The 2025 ACC/AHA/SCAI guidelines assign this a Class IIa recommendation (reasonable to perform), acknowledging that while the evidence is not as robust as for early presentation, clinical benefit exists 1. Research demonstrates that 65% of patients presenting 12-72 hours after symptom onset achieve substantial myocardial salvage (salvage index ≥0.50) with PCI 3.

Beyond 24 Hours After Symptom Onset

PCI is reasonable ONLY if:

• Ongoing ischemia is present (continuing chest pain, ST-segment elevation) 1
• Life-threatening arrhythmias occur (ventricular tachycardia/fibrillation) 1
• Acute severe heart failure develops 1
• Cardiogenic shock is present (Class I indication regardless of time) 1

This carries a Class IIa recommendation with Level C-LD evidence 1.

When NOT to Perform PCI After 12 Hours

PCI should NOT be performed (Class III: No Benefit) in:

• Stable, asymptomatic patients with totally occluded infarct-related artery >24 hours after symptom onset 1
• No evidence of ongoing ischemia (resolved chest pain, normalized ST segments) 1
• No hemodynamic compromise 1
• No life-threatening arrhythmias 1

The landmark OAT trial demonstrated that PCI in stable patients with occluded infarct arteries 3-28 days after symptom onset did not improve clinical outcomes 1. This represents Level B evidence against intervention in stable late presenters 1.

Supporting Evidence for Late PCI

Myocardial Salvage Data

Real-world evidence strongly supports PCI beyond 12 hours when appropriately selected:

• The BRAVE-2 trial showed significant myocardial salvage in patients treated 12-48 hours after symptom onset, with salvage index of 0.44 in the PCI group versus 0.23 in conservative management (P<0.001) 4
• A Chinese registry study of 1,072 STEMI patients demonstrated that delayed PCI >12 hours reduced all-cause mortality (9.3% vs 28.9%, P<0.001) and cardiac death (7.9% vs 25.1%, P<0.001) compared to medical therapy alone 5
• Cardiac MRI studies confirm that despite larger final infarct size in late presenters, substantial myocardial salvage occurs in the majority of patients with ongoing ischemia 3

Critical Distinction: Stable vs Unstable Patients

The key divergence in guidelines centers on patient stability 1:

• European Society of Cardiology (2008) states there is "no consensus" for PCI >12 hours without ongoing ischemia, citing the OAT trial 1
• ACC/AHA guidelines (2025) provide clearer direction: reasonable for unstable patients 12-24 hours, and for those >24 hours only with high-risk features 1

Practical Clinical Algorithm

For patients presenting 12-24 hours after symptom onset:

1. Assess for high-risk features (ongoing chest pain, ST elevation, hemodynamic instability, heart failure, arrhythmias) 1
2. If ANY high-risk feature present → Proceed with primary PCI 1
3. If stable and asymptomatic → Consider PCI reasonable but not mandatory; may defer to risk stratification 1

For patients presenting >24 hours after symptom onset:

1. Assess for ongoing ischemia (persistent symptoms, ST elevation) 1
2. Check hemodynamic status (shock, severe heart failure) 1
3. Evaluate for life-threatening arrhythmias 1
4. If ANY of above present → Proceed with PCI 1
5. If stable, asymptomatic, no ongoing ischemia → Do NOT perform PCI (Class III) 1

Common Pitfalls to Avoid

• Performing PCI in stable patients >24 hours without evidence of ongoing ischemia—this provides no benefit and exposes patients to procedural risk 1
• Assuming all late presenters need PCI—patient selection based on ongoing ischemia is critical 1
• Ignoring cardiogenic shock as an absolute indication—these patients benefit from emergency revascularization regardless of time from symptom onset 1
• Failing to assess for contraindications when considering alternative fibrinolytic therapy in very late presenters without PCI access 2, 6

Time Goals When PCI is Indicated

Even in late presenters, minimize door-to-balloon time when PCI is indicated 1. The 2025 guidelines maintain system goals of ≤90 minutes for PCI-capable hospitals and ≤120 minutes for transfer patients, though these primarily apply to early presenters 1.