Resolution of ST Elevation After Reperfusion Therapy in Myocardial Infarction
Complete ST-segment resolution typically occurs within 60-90 minutes after successful reperfusion therapy in STEMI patients, with >70% resolution being a strong indicator of effective myocardial reperfusion and improved outcomes. 1, 2
Assessment of Reperfusion Success
- ST-segment resolution is a key marker used to evaluate the effectiveness of reperfusion therapy after STEMI, with complete resolution (>70%) strongly associated with successful myocardial reperfusion 1
- The assessment of reperfusion should be performed at 60-90 minutes after initiation of fibrinolytic therapy 1
- Lack of ST resolution by at least 50% in the lead showing the greatest elevation at 60-90 minutes indicates likely failed reperfusion and should prompt consideration for rescue PCI 1
ST Resolution Patterns and Timing
- Complete ST resolution (>70%) at 60 minutes after reperfusion therapy is associated with limited myocardial damage and excellent clinical outcomes 2, 3
- Partial ST resolution (30-70%) typically indicates intermediate success of reperfusion 2
- Minimal or no ST resolution (<30%) at 60-90 minutes suggests failed reperfusion and is associated with worse outcomes 1, 2
Clinical Implications of ST Resolution Timing
- The combination of <50% ST resolution and absence of reperfusion arrhythmias at 2 hours after treatment predicts TIMI flow <3 with high sensitivity (81%) and specificity (88%) 1
- Patients with complete ST resolution at 60 minutes have significantly lower 30-day mortality (2.1%) compared to those with partial resolution (5.2%), no resolution (5.5%), or worsening ST elevation (8.1%) 3
- The relative risk of death is 8.7 times higher in patients with no ST resolution compared to those with normalized ST segments 2
Management Based on ST Resolution
- If ST elevation fails to resolve by at least 50% at 60-90 minutes after fibrinolytic therapy, immediate coronary angiography and rescue PCI should be performed 1
- For patients with successful fibrinolysis (indicated by ST resolution), coronary angiography should ideally be performed within 3-24 hours, but not within the first 2-3 hours after fibrinolytic administration 1
- The "trifecta" of successful reperfusion (TFG 3 flow, MPG 3 perfusion, and complete ST resolution) at 60 minutes is associated with very low rates of 30-day mortality and heart failure 4
Important Considerations and Pitfalls
- ST resolution should not be used as the sole criterion for reperfusion success; clinical symptoms (relief of chest pain) and reperfusion arrhythmias should also be considered 1
- Complete relief of pain combined with >70% ST resolution in the index lead is highly suggestive of restoration of normal myocardial blood flow 1
- Partial or absent improvement in ST elevation is less accurate in predicting a "closed artery" than complete resolution is in predicting an "open artery" 1
- Waiting too long to assess ST resolution may miss the window for rescue PCI in patients with failed fibrinolysis 1