Streptokinase Use in STEMI When Primary PCI Is Not Feasible

Indications and Dosing

Streptokinase 1.5 million units should be given intravenously over 30–60 minutes to patients presenting within 12 hours of symptom onset who cannot undergo primary PCI within 90–120 minutes and have no contraindications. [1][2]
The recommended preparation is 1.5 million units diluted in 100 mL of 5 % dextrose or 0.9 % saline and infused over 30–60 minutes. 1

Timing of Administration

Initiate streptokinase as soon as possible after STEMI diagnosis, aiming for a door‑to‑needle time ≤30 minutes. [3][2]
Pre‑hospital administration is advised when trained personnel are available and primary PCI cannot be performed within 120 minutes. [3][2]
The greatest clinical benefit is observed when treatment is started within 6 hours of symptom onset; therapy may still be given up to 12 hours in patients with persistent ST‑elevation. [1][4]2

Adjunctive Antiplatelet Therapy

Give a chewed loading dose of aspirin 150–325 mg (non‑enteric) immediately, followed by 75–100 mg daily indefinitely. [3][1]2
Add clopidogrel 75 mg daily to aspirin and continue throughout hospitalization; the combination reduces death, reinfarction, and stroke by approximately 9 events per 1,000 treated. [5][2]

Anticoagulation Strategy

Heparin is optional but recommended for high‑risk patients (e.g., anterior MI, heart failure, atrial fibrillation, left‑ventricular thrombus). [3][1]
Unfractionated heparin: weight‑adjusted IV bolus followed by a 24–48 hour infusion targeting an aPTT of 50–70 seconds. [3][1]
Enoxaparin may be used with dose reduction in patients ≥75 years or with creatinine clearance < 30 mL/min. [5][2]
aPTT values >70 seconds are linked to higher mortality and bleeding; close monitoring is mandatory. 5

Contraindications

Absolute contraindications: any history of hemorrhagic stroke, central‑nervous‑system damage or neoplasm, recent major trauma/surgery/head injury (<3 weeks), gastrointestinal bleeding within the past month, known bleeding disorder, aortic dissection, or prior streptokinase/anistreplase exposure (antibodies persist ≥10 years). [1][5]6
Relative contraindications: pregnancy or within 1 week postpartum, non‑compressible puncture sites, traumatic resuscitation, advanced liver disease, infective endocarditis, active peptic ulcer. [1][5]

Reperfusion Assessment

At 60–90 minutes after the start of streptokinase, assess ST‑segment resolution in the lead with the greatest initial elevation. ≥50 % resolution indicates successful reperfusion; <50 % indicates failure. 2

Rescue PCI and Transfer

Immediate rescue PCI is indicated for failed fibrinolysis (ST‑resolution <50 % at 60–90 minutes), hemodynamic instability or cardiogenic shock, sustained ventricular arrhythmias, or worsening ischemia/re‑occlusion. [4][2]
All patients should be transferred promptly to a PCI‑capable center after fibrinolysis for possible rescue or routine angiography. 2

Post‑Fibrinolysis Angiography

After successful fibrinolysis, perform angiography and PCI of the infarct‑related artery within 2–24 hours; very early angiography (<2 hours) does not increase bleeding or adverse outcomes. 6
Emergency angiography is required for patients developing heart failure, cardiogenic shock, or recurrent ischemia. 2

Safety Pitfalls

Do not re‑administer streptokinase; antibodies persist for at least 10 years and can cause allergic reactions and treatment failure. [1][5]6
If re‑occlusion occurs, switch to a non‑immunogenic fibrin‑specific agent (alteplase, reteplase, or tenecteplase) or proceed to rescue PCI. [3][1]
Monitor for transient hypotension during infusion; reduce infusion rate if hypotension develops. 6

Comparison with Fibrin‑Specific Agents

When available, fibrin‑specific agents (tenecteplase, alteplase) are preferred because they reduce mortality by an additional ~10 deaths per 1,000 patients compared with streptokinase. [1][5]
Streptokinase remains a reasonable alternative when cost or availability limits the use of fibrin‑specific agents. [3][1]

Thrombolysis Criteria for Myocardial Infarction

Inclusion Criteria for Thrombolysis

The European Society of Cardiology recommends fibrinolytic therapy for STEMI patients presenting within 12 hours of symptom onset with persistent ST-segment elevation or new left bundle branch block, when primary PCI cannot be performed within 120 minutes of diagnosis and there are no contraindications 7, 8
Symptoms of ischemia lasting ≤12 hours from onset to treatment are required for thrombolysis 7, 8, 9
Persistent ST-segment elevation on ECG is a necessary condition for thrombolysis 7, 8, 9

Timing Considerations

Primary PCI cannot be performed within 120 minutes of STEMI diagnosis, making fibrinolysis a suitable alternative 7, 8, 10
Fibrinolysis should be initiated as soon as possible, preferably in the pre-hospital setting to minimize time delays 7, 8, 9, 11

Recommended Fibrinolytic Agents and Dosing

The European Heart Society recommends using a fibrin-specific agent: tenecteplase, alteplase, or reteplase 7, 8, 9, 11
For patients ≥75 years old, the American College of Cardiology recommends reducing tenecteplase dose by 50% to minimize stroke risk 10

Adjunctive Antithrombotic Therapy

The European Society of Cardiology recommends oral or IV aspirin (150-325 mg) as soon as possible, in addition to fibrinolysis 7, 8, 9, 11
Clopidogrel in addition to aspirin is recommended by the European Heart Society 7, 8, 9, 11
Anticoagulation with enoxaparin or unfractionated heparin is required until revascularization or up to 8 days of hospitalization 7, 8, 9, 11

Post-Fibrinolysis Management Algorithm

The American Heart Association recommends transferring all patients to a PCI-capable center immediately after fibrinolysis 7, 8, 9, 11
At 60-90 minutes after fibrinolysis initiation, assess for successful reperfusion by measuring ST-segment resolution in the lead with greatest initial ST elevation 7, 8, 9, 12
Less than 50% ST-segment resolution indicates failed fibrinolysis 7, 8, 12

Rescue PCI Indications

The European Society of Cardiology recommends performing rescue PCI immediately when failed fibrinolysis (<50% ST-segment resolution at 60-90 minutes) occurs 7, 8, 9, 12
Hemodynamic instability, electrical instability, worsening ischemia, or cardiogenic shock are also indications for rescue PCI 7, 8, 9, 13, 12

Routine Angiography After Successful Fibrinolysis

The American College of Cardiology recommends performing angiography and PCI of the infarct-related artery between 2-24 hours after successful fibrinolysis 7, 8, 9, 11

Emergency Angiography Indications

The European Heart Society recommends performing emergency angiography and PCI immediately in cases of heart failure, cardiogenic shock, recurrent ischemia, or evidence of reocclusion after initial successful fibrinolysis 7, 8, 9, 11

Special Considerations

The American Heart Association recommends against routinely combining fibrinolysis with planned immediate PCI, as this increases mortality and other adverse outcomes 7, 8, 9
In asymptomatic patients >48 hours after STEMI onset, routine PCI of an occluded infarct-related artery is not indicated by the European Society of Cardiology 7, 8, 9
When primary PCI can be performed within 120 minutes, it is the preferred reperfusion strategy over fibrinolysis, according to the European Heart Society 7, 8, 10

Rescue PCI Indications and Outcomes After Failed Fibrinolysis in STEMI

Primary Indication – Failed Reperfusion

Immediate rescue PCI is indicated when ST‑segment resolution is < 50 % on the 60‑90 minute ECG after fibrinolytic therapy, reflecting failed reperfusion and conferring a significant survival advantage over conservative care or repeat fibrinolysis. (American College of Cardiology) 14
Assessment at 60–90 minutes post‑fibrinolysis should focus on the lead with the greatest initial ST‑elevation; < 50 % resolution mandates rescue PCI. (American College of Cardiology) 15

High‑Risk Clinical Scenarios

Hemodynamic Instability

Cardiogenic shock warrants rescue PCI (Class I for patients < 75 y, Class IIa for ≥ 75 y). (American College of Cardiology) 14
Persistent hypotension or any sign of shock also mandates rescue PCI. (American College of Cardiology) 14

Electrical Instability

Life‑threatening ventricular arrhythmias that persist despite optimal medical therapy require rescue PCI. (American College of Cardiology) 14

Ongoing Ischemia

Continued or worsening chest pain after fibrinolysis is an indication for rescue PCI. (American College of Cardiology) 16
Development of acute heart failure or pulmonary edema signals the need for rescue PCI. (American College of Cardiology) 15

Timing Considerations

The earlier rescue PCI is performed, the greater the benefit; myocardial salvage is unlikely if coronary occlusion exceeds 3–6 hours from symptom onset. (Circulation) 17
Even with the inherent delay of a fibrinolysis‑then‑rescue pathway, rescue PCI still yields a significant mortality reduction. (Circulation) 16

Clinical Assessment Algorithm

Always obtain a 60‑90 minute ECG; clinical markers such as pain relief or reperfusion arrhythmias have limited predictive value and should not replace ECG assessment. (Circulation) 17

Outcomes and Evidence Strength

Rescue PCI reduces the composite of death or reinfarction from 16.8 % to 10.8 % (RR 0.64, p = 0.009) compared with conservative management. (Circulation) 16
All‑cause mortality falls from 10.7 % to 6.9 % (RR 0.65, p = 0.04) with rescue PCI. (Circulation) 18
Procedural success is high, but failure to restore flow occurs in ≈ 10 % of cases, and re‑occlusion rates can reach ≈ 20 % (improved with modern stents and GP IIb/IIIa inhibitors). (Circulation) 19
The mortality benefit outweighs procedural risks, including a modest increase in stroke risk. (Circulation) 16
Evidence is derived from multiple randomized trials (REACT, MERLIN, RESCUE) and meta‑analyses encompassing > 1,100 patients, consistently demonstrating benefit. (American College of Cardiology; Circulation) 14
Modern trials using drug‑eluting stents and GP IIb/IIIa inhibitors show superior outcomes compared with earlier balloon‑only studies. (Circulation) 18

Practical Implementation

All patients who receive fibrinolysis should be transferred immediately to a PCI‑capable center; approximately 30 % will require rescue PCI. (American College of Cardiology) 14
Routine angiography is recommended within 2–24 hours for patients with successful reperfusion (≥ 50 % ST‑resolution). (American College of Cardiology) 15