How should tenecteplase be administered for a patient with acute ST‑segment elevation myocardial infarction when primary PCI cannot be performed within the recommended time window?

Tenecteplase Administration in STEMI When Primary PCI is Unavailable

When primary PCI cannot be performed within 120 minutes of first medical contact, administer tenecteplase as a single weight-based IV bolus within 30 minutes of hospital arrival (or ideally within 10 minutes of STEMI diagnosis in the pre-hospital setting), provided there are no contraindications to fibrinolysis. 1, 2, 3, 4

Timing Criteria for Fibrinolytic Therapy

The decision to use tenecteplase hinges on specific time windows:

• Primary PCI preferred if achievable within 90 minutes of first medical contact at a PCI-capable center 1
• Transfer for primary PCI preferred if achievable within 120 minutes of first medical contact when at a non-PCI-capable facility 1
• Administer tenecteplase when anticipated first medical contact-to-device time exceeds 120 minutes 1, 2, 3, 4

The greatest benefit occurs when fibrinolysis is given within the first 2 hours of symptom onset, particularly in patients with large anterior infarctions and low bleeding risk 1, 4. Treatment within 12 hours of symptom onset is standard, though consideration may be given to patients presenting 12-24 hours after symptoms if they have large areas of myocardium at risk or hemodynamic instability 3, 4.

Tenecteplase Dosing

Administer as a single IV bolus based on body weight 3, 4, 5:

• <60 kg: 30 mg
• 60-69 kg: 35 mg
• 70-79 kg: 40 mg
• 80-89 kg: 45 mg
• ≥90 kg: 50 mg

For patients ≥75 years of age, use half-dose tenecteplase to reduce intracranial hemorrhage risk 6, 7. The STREAM-2 trial demonstrated that half-dose tenecteplase in patients ≥60 years achieved comparable ST-segment resolution and clinical outcomes to primary PCI, though with a 1.5% intracranial hemorrhage rate (versus 0% with PCI) 6.

Mandatory Adjunctive Therapy

Aspirin: 150-325 mg orally (chewable, non-enteric coated) or IV if unable to swallow 2

P2Y12 Inhibitor: Clopidogrel loading dose (300-600 mg) in addition to aspirin 2

Anticoagulation (choose one) 2:

• Enoxaparin (preferred): 30 mg IV bolus, followed 15 minutes later by 1 mg/kg subcutaneous every 12 hours (reduce to 0.75 mg/kg if age ≥75 years; avoid if creatinine clearance <15 mL/min)
• Unfractionated heparin: 60 units/kg IV bolus (maximum 4000 units), followed by 12 units/kg/hour infusion (maximum 1000 units/hour), adjusted to aPTT 1.5-2 times control

Continue anticoagulation until revascularization or for duration of hospital stay up to 8 days 2.

Absolute Contraindications to Tenecteplase

Screen carefully for the following 3, 4, 5:

• Any prior intracranial hemorrhage
• Known structural cerebral vascular lesion (AVM, aneurysm)
• Known intracranial malignancy
• Ischemic stroke within 3 months
• Suspected aortic dissection
• Active bleeding or bleeding diathesis
• Significant closed-head or facial trauma within 3 months
• Intracranial/intraspinal surgery within 2 months
• Severe uncontrolled hypertension (SBP >180 mmHg or DBP >110 mmHg unresponsive to therapy)

Post-Fibrinolysis Management

Immediate transfer to PCI-capable center is mandatory for all patients after fibrinolysis 2. The post-fibrinolysis strategy depends on clinical response:

Assess ST-Segment Resolution at 60-90 Minutes

• <50% ST-segment resolution: Proceed immediately to rescue PCI 2
• ≥50% ST-segment resolution (successful fibrinolysis): Perform angiography with PCI if indicated between 2-24 hours after fibrinolysis 2
• Hemodynamic instability, electrical instability, or worsening ischemia at any time: Emergency angiography and PCI 2

Critical Pitfalls to Avoid

Do not use tenecteplase with planned immediate primary PCI. The ASSENT-4 PCI trial was terminated early due to worse outcomes when tenecteplase was given before planned PCI (18.6% vs 13.4% composite endpoint of death/shock/CHF; higher rates of recurrent MI and repeat revascularization) 5. If PCI is immediately available, proceed directly to catheterization without fibrinolysis 5.

Avoid excess anticoagulation, particularly in elderly patients. Protocol violations with excessive anticoagulation contributed to intracranial hemorrhages in the STREAM-2 trial 6. Strict adherence to weight-based dosing and monitoring is essential.

Monitor blood pressure aggressively. Ensure SBP <180 mmHg and DBP <110 mmHg before and after administration 3, 4.

Minimize invasive procedures. Avoid intramuscular injections, internal jugular/subclavian venous punctures, and nonessential handling for the first few hours. If arterial puncture is necessary, use upper extremity vessels accessible to manual compression with at least 30 minutes of pressure 5.

Advantages of Tenecteplase Over Alteplase

Tenecteplase is the preferred fibrin-specific agent due to 8, 2, 3, 4:

• Single bolus administration (versus 90-minute infusion for alteplase)
• Equivalent 30-day mortality to alteplase
• Reduced non-cerebral bleeding compared to alteplase
• Higher fibrin specificity
• Easier pre-hospital administration

The 2017 ESC guidelines specifically recommend fibrin-specific agents (tenecteplase, alteplase, or reteplase), with tenecteplase offering practical advantages 2.

Pre-Hospital Administration

Pre-hospital fibrinolysis is recommended when appropriate facilities exist 1, 2. The STREAM trial demonstrated that pre-hospital tenecteplase with timely angiography achieved effective reperfusion in early-presenting STEMI patients, with median time from randomization to drug of 10 minutes versus 81 minutes to sheath insertion for primary PCI 7. In rural settings, this can save approximately 2 hours compared to PCI strategies 9.