What are the indications for thrombolysis in ST-Elevation Myocardial Infarction (STEMI)?

Indications for Thrombolysis in ST-Elevation Myocardial Infarction (STEMI)

Thrombolysis is indicated in STEMI patients when primary PCI cannot be performed in a timely manner, specifically within 12 hours of symptom onset and when primary PCI cannot be achieved within 120 minutes of STEMI diagnosis. 1

Primary Indications

• Timing from symptom onset:

  • Patients with symptoms of ischemia of ≤12 hours duration and persistent ST-segment elevation 1
  • Most beneficial when administered within the first 1-2 hours of symptom onset 1
  • Should be initiated as soon as possible after STEMI diagnosis, preferably in the pre-hospital setting 1

• Unavailability of timely PCI:

  • When primary PCI cannot be performed within 120 minutes of STEMI diagnosis 1
  • For patients <75 years with a large anterior infarction presenting within 2 hours, PCI should be performed within 90 minutes; otherwise, thrombolysis is preferred 2

Agent Selection and Administration

• Preferred agents:

  • A fibrin-specific agent is recommended (tenecteplase, alteplase, or reteplase) 1
  • Tenecteplase is administered as a single weight-based IV bolus 3
  • Alteplase is given as a 90-minute weight-based infusion 1
  • Reteplase is administered as two 10-U IV boluses given 30 minutes apart 1

• Adjunctive therapy:

  • Oral or IV aspirin is indicated 1
  • Clopidogrel is indicated in addition to aspirin 1
  • Anticoagulation is recommended until revascularization or for the duration of hospital stay (up to 8 days) 1
    • Enoxaparin IV followed by SC (preferred over UFH) 1
    • UFH given as a weight-adjusted IV bolus followed by infusion 1

Absolute Contraindications 1

• Any prior intracranial hemorrhage
• Known structural cerebral vascular lesion
• Known malignant intracranial neoplasm
• Ischemic stroke within 3 months (except acute ischemic stroke within 4.5 hours)
• Suspected aortic dissection
• Active bleeding or bleeding diathesis
• Significant closed-head or facial trauma within 3 months
• Intracranial or intraspinal surgery within 2 months
• Severe uncontrolled hypertension
• For streptokinase, prior treatment within previous 6 months

Relative Contraindications 1

• History of chronic, severe, poorly controlled hypertension
• Significant hypertension on presentation (SBP >180 mm Hg or DBP >110 mm Hg)
• History of prior ischemic stroke >3 months
• Dementia
• Known intracranial pathology not covered in absolute contraindications
• Traumatic or prolonged CPR (>10 min)
• Major surgery (<3 weeks)
• Recent internal bleeding (within 2-4 weeks)
• Noncompressible vascular punctures
• Pregnancy
• Active peptic ulcer
• Oral anticoagulant therapy

Post-Thrombolysis Management

• Transfer to a PCI-capable center following fibrinolysis is indicated in all patients immediately after fibrinolysis 1
• Emergency angiography and PCI if indicated is recommended in patients with heart failure/shock 1
• Rescue PCI is indicated immediately when fibrinolysis has failed (<50% ST-segment resolution at 60-90 min) 1
• Angiography and PCI of the infarct-related artery is recommended between 2-24 hours after successful fibrinolysis 1
• Emergency angiography and PCI is indicated in case of recurrent ischemia or evidence of reocclusion after initial successful fibrinolysis 1

Special Considerations

• For very early presenters (within 1-2 hours of symptom onset) with low bleeding risk, thrombolysis may be particularly beneficial 1, 4
• In patients presenting >12 hours after symptom onset, thrombolysis has not shown established benefit, but may be considered in symptomatic patients with a large area of myocardium at risk or hemodynamic instability if PCI is unavailable 1
• Patients with resuscitated cardiac arrest and ECG consistent with STEMI should preferably undergo primary PCI rather than thrombolysis 1, 5

Common Pitfalls and Caveats

• Avoid delaying thrombolysis when primary PCI cannot be performed within the recommended timeframes
• Do not administer thrombolysis without checking for contraindications
• Remember that thrombolysis is only effective in approximately 50-60% of cases, compared to >90% effectiveness with primary PCI 6
• Avoid using non-fibrin-specific agents when fibrin-specific agents are available
• Do not forget to transfer patients to a PCI-capable center after thrombolysis, regardless of apparent success
• Monitor closely for bleeding complications, which are the most common adverse events with thrombolytic therapy 3
• Ensure appropriate anticoagulation and antiplatelet therapy is administered concomitantly 7

By following these guidelines, thrombolysis can be effectively used as a reperfusion strategy in STEMI patients when primary PCI cannot be performed in a timely manner, reducing mortality and improving outcomes.