What are the timing criteria for administering intravenous fibrinolytics (e.g. alteplase, tenecteplase, streptokinase) to a patient with ongoing chest pain and no immediate access to percutaneous coronary intervention (PCI)?

Timing Criteria for Fibrinolytic Therapy in STEMI

Administer intravenous fibrinolytics to this patient with ongoing chest pain for <12 hours when percutaneous coronary intervention (PCI) cannot be performed within 120 minutes of first medical contact. 1, 2

Primary Indication

The ACC/AHA guidelines provide a Class I, Level A recommendation that fibrinolytic therapy should be given to patients with STEMI and onset of ischemic symptoms within the previous 12 hours when it is anticipated that primary PCI cannot be performed within 120 minutes of first medical contact (FMC). 1

• First medical contact is defined as either the call to emergency medical services or self-presentation at the hospital 3
• The 120-minute threshold represents the time from FMC to device (balloon inflation), not just arrival at a PCI-capable facility 1
• This patient presented 2 hours ago with ongoing symptoms, placing him well within the <12 hour window for fibrinolytic benefit 1

Clinical Algorithm for This Rural ED Case

Step 1: Confirm STEMI diagnosis and symptom duration

• This patient has substernal chest pressure with left arm paresthesias, dyspnea, and concerning vital signs (tachycardia, hypertension, tachypnea, crackles) 4
• Symptom onset approximately 2 hours ago places him in the optimal window for reperfusion therapy 1

Step 2: Assess PCI availability

• In a rural emergency department, determine if transfer to a PCI-capable facility can achieve device time within 120 minutes of FMC 1, 2
• If anticipated FMC-to-device time exceeds 120 minutes, fibrinolytic therapy is indicated 1

Step 3: Verify no contraindications

• The only ECG contraindication is ST depression (unless true posterior MI or ST elevation in aVR) - Class III: Harm 1, 2
• Absolute contraindications include prior intracranial hemorrhage, known structural cerebral vascular lesions, ischemic stroke within 3 months, active bleeding, or severe uncontrolled hypertension 2
• This patient's blood pressure of 198/100 mmHg requires consideration but is not an absolute contraindication if controlled 2

Why 120 Minutes Is the Critical Threshold

The evidence demonstrates that primary PCI is superior to fibrinolysis when the PCI-related delay is <120 minutes. 1, 3 However, when this threshold is exceeded, the mortality benefit of immediate fibrinolysis outweighs waiting for delayed PCI. 1, 4

• The 2015 International Consensus on Cardiopulmonary Resuscitation provides nuanced guidance: for patients presenting <2 hours from symptom onset with anticipated PCI delay >60 minutes, fibrinolysis is suggested; for those presenting 2-3 hours after onset with PCI delay 60-120 minutes, either strategy is reasonable 1
• For patients presenting >6 hours after symptom onset, PCI becomes preferred even with delays >120 minutes, as fibrinolysis loses effectiveness 1
• This patient at 2 hours from onset falls in the window where fibrinolysis provides maximal benefit if PCI cannot be achieved within 120 minutes 1

Extended Time Window Considerations

Class IIa recommendation (Level C): Fibrinolytic therapy is reasonable for patients with STEMI if there is clinical and/or electrocardiographic evidence of ongoing ischemia within 12 to 24 hours of symptom onset when PCI is not available AND there is a large area of myocardium at risk or hemodynamic instability. 1

• This patient shows evidence of ongoing ischemia (chest pain, ECG changes) and hemodynamic stress (tachycardia, hypertension, pulmonary crackles suggesting heart failure) 1
• Even if he were beyond 12 hours, these high-risk features would support fibrinolytic consideration 1

Post-Fibrinolysis Management

Following fibrinolytic administration, this patient requires:

• Adjunctive antiplatelet therapy: Aspirin 162-325 mg loading dose and clopidogrel 300 mg loading dose (he appears <75 years old based on context) 1
• Anticoagulation: Minimum 48 hours, preferably for duration of hospitalization up to 8 days 1
• Transfer to PCI-capable facility: For coronary angiography within 3-24 hours as part of a pharmaco-invasive strategy 1, 5
• Door-to-needle time goal: ≤30 minutes from hospital arrival to fibrinolytic administration 1

Common Pitfalls to Avoid

Do not confuse FMC-to-PCI delay with PCI-related delay: The 120-minute threshold refers to the anticipated time from first medical contact to device deployment, not the time from fibrinolytic administration to PCI. 3

Do not withhold fibrinolytics based on the incorrect 90-minute threshold: While 90 minutes is the goal for FMC-to-device time when presenting directly to a PCI-capable hospital, the threshold for choosing fibrinolysis over transfer is 120 minutes. 1

Do not delay for "stabilization": The survival benefit is greatest when fibrinolytics are administered within the first 2 hours after symptom onset. 1 This patient at 2 hours is still in an optimal window, but every minute counts. 1, 4

Do not use the 240-minute threshold: This is not supported by any major guideline and would result in unacceptable delays to reperfusion. 1