Is streptokinase appropriate for acute ST‑segment‑elevation myocardial infarction, and what are the recommended dose and contraindications?

Streptokinase Dosing and Use in Acute Myocardial Infarction

Recommended Dose

Streptokinase is administered as 1.5 million units intravenously over 30 to 60 minutes for ST-segment elevation myocardial infarction. 1

• The standard infusion time is 30-60 minutes, with both durations showing similar efficacy and safety profiles 1, 2, 3
• An accelerated 30-minute infusion may achieve faster reperfusion compared to 60-minute infusion, with higher rates of successful reperfusion (62% vs 38%) and better preserved ejection fraction, without increased adverse events 2
• The dose remains 1.5 million units regardless of patient weight 1

When Streptokinase is Appropriate

Streptokinase should only be used when fibrin-specific agents (tenecteplase, alteplase, reteplase) are unavailable, as these newer agents demonstrate superior outcomes. 1, 4

Clinical Indications for Fibrinolytic Therapy (Including Streptokinase):

• Patients with ST-elevation or new left bundle branch block presenting within 12 hours of symptom onset 1
• Primary PCI cannot be performed within 120 minutes of first medical contact 1, 5
• No absolute contraindications to fibrinolysis are present 1

Why Streptokinase is Second-Line:

• Fibrin-specific agents (alteplase, tenecteplase) are strongly preferred over streptokinase for patients presenting within 6 hours of symptom onset due to superior mortality reduction 4, 6
• Streptokinase achieves only 60-68% TIMI 2 or 3 flow at 90 minutes, compared to 73-85% with fibrin-specific agents 1
• Streptokinase is no longer marketed in the United States but remains available in other countries where cost considerations may favor its use 1

Critical Contraindications Specific to Streptokinase

Streptokinase is absolutely contraindicated if the patient received streptokinase within the previous 6 months due to high risk of serious allergic reaction from antibody formation. 1

All Absolute Contraindications to Fibrinolytic Therapy:

• Any prior intracranial hemorrhage 1
• Known structural cerebrovascular lesion (arteriovenous malformation) 1
• Known malignant intracranial neoplasm 1
• Ischemic stroke within 3 months (except acute ischemic stroke within 4.5 hours) 1
• Suspected aortic dissection 1, 7
• Active bleeding or bleeding diathesis (excluding menses) 1
• Significant closed-head or facial trauma within 3 months 1
• Intracranial or intraspinal surgery within 2 months 1
• Severe uncontrolled hypertension unresponsive to emergency therapy 1
• Prior streptokinase treatment within 6 months (streptokinase-specific) 1

Essential Adjunctive Therapy

All patients receiving streptokinase must receive aspirin and clopidogrel, plus anticoagulation with enoxaparin or unfractionated heparin. 1, 5, 4

Antiplatelet Regimen:

• Aspirin 162-325 mg loading dose immediately 1
• Clopidogrel 300 mg loading dose for patients <75 years; 75 mg for patients ≥75 years 1
• Continue aspirin indefinitely and clopidogrel for at least 14 days, up to 1 year 1

Anticoagulation:

• Enoxaparin (IV bolus followed by subcutaneous) is preferred over unfractionated heparin 5, 8
• Alternative: weight-adjusted unfractionated heparin bolus with infusion 5

Mandatory Post-Fibrinolysis Management

Every patient receiving streptokinase must be transferred immediately to a PCI-capable center for angiography within 2-24 hours, regardless of apparent clinical success. 5, 7, 8

Assessment and Rescue Strategy:

• Assess ST-segment resolution at 60-90 minutes post-fibrinolysis 5, 7, 8
• Perform rescue PCI immediately if <50% ST-segment resolution occurs 5, 8
• Emergency angiography is indicated for hemodynamic instability, electrical instability, heart failure, or recurrent ischemia 5, 8
• In stable patients with successful fibrinolysis, perform routine angiography 2-24 hours after thrombolysis 5, 8

Critical Pitfalls to Avoid

• Never delay transfer to a PCI-capable center after streptokinase administration—transfer must be arranged immediately, not after observing the patient 5, 7
• Never use streptokinase in patients with prior streptokinase exposure ≥6 months ago due to antibody-mediated allergic reactions and reduced efficacy 1
• Never choose streptokinase when fibrin-specific agents are available, particularly for anterior MI or presentation within 4 hours 4, 6
• Do not administer streptokinase to patients with ST-depression only (unless true posterior MI suspected) 1

Special Considerations

• Streptokinase is highly antigenic and can cause allergic reactions including anaphylaxis 1
• Hypotension occurs more frequently with streptokinase than fibrin-specific agents and may require vasopressor support 7
• In cardiogenic shock, streptokinase can be used when primary PCI is unavailable, but immediate transfer for rescue PCI must be arranged 7