Should tenecteplase (tissue plasminogen activator) be administered in a patient with ST elevation myocardial infarction (STEMI) and negative troponin (cardiac biomarker)?

Management of STEMI with Negative Troponin T

Tenecteplase should be administered in a patient with ST-elevation myocardial infarction (STEMI) despite negative troponin T, as the diagnosis of STEMI is based primarily on ECG findings rather than biomarkers, and early reperfusion therapy significantly reduces mortality regardless of initial troponin status. 1

Rationale for Tenecteplase Administration

• STEMI is primarily diagnosed by ECG criteria, not troponin levels, and immediate reperfusion therapy is indicated based on ST-segment elevation pattern 1
• Troponin may be negative in the early hours after symptom onset, especially when the patient presents within the first 2-4 hours of symptoms 1
• The benefits of fibrinolytic therapy in STEMI are well-established, with a time-dependent reduction in mortality and morbidity during the initial 12 hours after symptom onset 1
• Tenecteplase is FDA-approved to reduce the risk of death associated with acute ST-elevation myocardial infarction 2

Tenecteplase Administration Protocol

• Administer tenecteplase as a single IV weight-based bolus over 5 seconds 1, 2:

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

• Initiate treatment as soon as possible after the onset of STEMI symptoms 2

• Administer adjunctive antiplatelet therapy with aspirin (162-325 mg loading dose) and clopidogrel (300 mg loading dose for patients <75 years, 75 mg for patients >75 years) 1

• Provide appropriate anticoagulant therapy for a minimum of 48 hours, and preferably for the duration of the index hospitalization 1

Contraindications to Tenecteplase

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 (unresponsive to therapy)

Post-Fibrinolytic Management

• Transfer all patients receiving fibrinolytic therapy to a PCI-capable hospital for routine coronary angiography 1
• Monitor for signs of failed reperfusion (lack of improvement in ischemic symptoms, persistent ST-segment elevation <50% resolution in anterior leads or <70% in inferior leads, hemodynamic or electrical instability) 1
• If signs of failed reperfusion are present, perform immediate coronary angiography and rescue PCI 1
• For patients with successful fibrinolysis, routine early catheterization (within 24 hours) followed by PCI when appropriate is recommended, as this approach has been shown to reduce mortality by 38% and reinfarction by 41% compared to delayed or ischemia-driven PCI 1

Special Considerations

• Tenecteplase has higher fibrin specificity and longer half-life than alteplase, allowing for single bolus administration 3, 4
• Tenecteplase and alteplase have equivalent 30-day mortality rates, but tenecteplase is associated with reduced non-cerebral bleeding 1, 3
• The benefit of fibrinolytic therapy is greatest when administered within the first 1-2 hours of symptom onset 1
• For patients presenting >12 hours after symptom onset, the benefit of fibrinolytic therapy has not been well established, but may be considered in symptomatic patients with a large area of myocardium at risk or hemodynamic instability if PCI is unavailable 1

Monitoring After Administration

• Monitor for bleeding complications, particularly intracranial hemorrhage 2
• Avoid intramuscular injections and noncompressible vascular punctures 2
• Be prepared to manage arrhythmias with appropriate anti-arrhythmic therapy 2
• Monitor for signs of hypersensitivity during and for several hours after infusion 2