What is the dose of FCM (Fibrinolytic therapy, likely referring to alteplase (tPA)) in myocardial infarction (MI) or acute coronary syndrome (ACS)?

FCM Dosing in Myocardial Infarction or Acute Coronary Syndrome

I believe you are asking about fibrinolytic therapy dosing for MI/ACS, not FCM (which typically refers to ferric carboxymaltose, an iron supplement). The standard fibrinolytic agents for STEMI are tenecteplase, alteplase, and streptokinase.

Preferred Agent: Tenecteplase (TNK-tPA)

Tenecteplase is the preferred fibrinolytic agent due to its single weight-based bolus administration and equivalent efficacy to alteplase. 1, 2

Weight-Based Dosing for Tenecteplase:

• <60 kg: 30 mg (6 mL) IV bolus 2
• 60-69 kg: 35 mg (7 mL) IV bolus 2
• 70-79 kg: 40 mg (8 mL) IV bolus 2
• 80-89 kg: 45 mg (9 mL) IV bolus 2
• ≥90 kg: 50 mg (10 mL) IV bolus 2

This single bolus achieves 85% TIMI 2-3 flow at 90 minutes and is particularly advantageous for pre-hospital administration. 2

Alternative Agent: Alteplase (tPA)

Use alteplase when a titratable infusion is needed or tenecteplase is unavailable. 1, 2

Accelerated Alteplase Regimen (90-minute protocol):

• 15 mg IV bolus (given over 1-2 minutes) 2, 3, 4
• Then 0.75 mg/kg over 30 minutes (maximum 50 mg) 2, 3, 4
• Then 0.5 mg/kg over 60 minutes (maximum 35 mg) 2, 3, 4
• Total dose must not exceed 100 mg 2, 3, 4

This accelerated regimen demonstrates superior mortality reduction compared to streptokinase (Grade 1A evidence) and achieves 73-84% TIMI 2-3 flow at 90 minutes. 2 The GUSTO trial established this as the standard alteplase dosing for STEMI. 5

Cost-Effective Alternative: Streptokinase

Use streptokinase only when cost is a major consideration or fibrin-specific agents are unavailable. 1, 2

Streptokinase Dosing:

• 1.5 million units IV over 30-60 minutes 1, 2

Critical Contraindication:

• Absolutely contraindicated within 6 months of previous streptokinase or anistreplase exposure due to antibody formation causing serious allergic reactions and impaired efficacy 2, 6

Streptokinase achieves only 60-68% TIMI 2-3 flow at 90 minutes but produces 42% mortality reduction when combined with aspirin. 2

Mandatory Adjunctive Antiplatelet Therapy

All patients receiving fibrinolysis must receive dual antiplatelet therapy regardless of which fibrinolytic is chosen. 1, 2

Aspirin:

• Loading dose: 150-325 mg (oral or IV if unable to swallow) 1, 2
• Maintenance: 75-100 mg daily indefinitely 1, 2

Clopidogrel:

• Loading dose: 300 mg for patients ≤75 years 2
• Loading dose: 75 mg for patients >75 years 2
• Maintenance: 75 mg daily for minimum 14 days 1, 2

Note: Clopidogrel is the P2Y12 inhibitor of choice during and after fibrinolysis, but switching to prasugrel or ticagrelor may be considered 48 hours after fibrinolysis if PCI is performed. 1

Required Anticoagulation

Anticoagulation is mandatory until revascularization or for duration of hospital stay up to 8 days. 1

For Tenecteplase or Alteplase - Enoxaparin (Preferred):

• Age <75 years: 30 mg IV bolus, then 1 mg/kg SC every 12 hours 1, 2
• Age ≥75 years: No IV bolus, 0.75 mg/kg SC every 12 hours 1, 2
• Renal adjustment: If eGFR <30 mL/min, reduce dose 1

Enoxaparin is preferred over UFH based on the ExTRACT-TIMI 25 trial, which showed reduced death or reinfarction (9.9% vs 12.0%) despite slightly increased major bleeding. 1

For Streptokinase - Fondaparinux:

• 2.5 mg IV bolus, then 2.5 mg SC once daily 1, 2

Alternative - Unfractionated Heparin:

• Weight-adjusted IV bolus followed by infusion 1
• Target aPTT: 50-70 seconds (aPTT >70 seconds associated with increased bleeding and mortality) 1

Timing Considerations

Fibrinolysis is indicated when primary PCI cannot be performed within 120 minutes of first medical contact. 1, 2

Time-Dependent Decision Algorithm:

• **Symptom onset <2 hours + large infarct + low bleeding risk:** Consider fibrinolysis if PCI delay >90 minutes 1, 2
• Symptom onset <12 hours: Fibrinolysis indicated if timely PCI unavailable 1
• Symptom onset >12 hours: Fibrinolysis generally not indicated unless ongoing ischemia 1

Initiate fibrinolytic therapy within 10 minutes of STEMI diagnosis, preferably in the pre-hospital setting. 1 Pre-hospital fibrinolysis reduces early mortality by 17% compared to in-hospital administration, particularly when given within first 2 hours. 1

Post-Fibrinolysis Management

All patients must be transferred to a PCI-capable center immediately after fibrinolysis. 1

Assessment of Reperfusion Success at 60-90 Minutes:

• Monitor for ≥50% ST-segment resolution 1, 2
• Relief of chest pain 1, 2
• Hemodynamic and electrical stability 1, 2

Post-Fibrinolysis PCI Strategy:

• Rescue PCI immediately if fibrinolysis failed (<50% ST-segment resolution) or hemodynamic/electrical instability 1
• Routine angiography and PCI between 2-24 hours after successful fibrinolysis 1
• Emergency angiography immediately for heart failure/shock or recurrent ischemia 1

Do NOT readminister fibrinolysis for failed lysis—proceed directly to rescue PCI. 1 Re-administration has not been shown to be beneficial and should be discouraged. 1

Critical Safety Considerations

Absolute Contraindications:

• Any prior intracranial hemorrhage 2
• Ischemic stroke within 3 months 2
• Known intracranial vascular malformation or neoplasm 2
• Active bleeding or bleeding diathesis 2
• Suspected aortic dissection 2
• Significant closed head/facial trauma within 3 months 2
• Intracranial/intraspinal surgery within 2 months 2
• Severe uncontrolled hypertension 2

Intracranial Hemorrhage Risk:

The overall risk is 0.9-1.0%, with increased risk in patients with lower weight, female sex, previous cerebrovascular disease, and hypertension on admission. 2 Alteplase carries slightly higher stroke risk than streptokinase but superior mortality benefit. 5

Common Pitfalls to Avoid

Do not use fondaparinux as sole anticoagulant for primary PCI—it is contraindicated in this setting. 1 Fondaparinux is only appropriate with streptokinase or in patients not undergoing immediate PCI. 1

Do not delay transfer to PCI-capable center after fibrinolysis—even with successful lysis, routine early angiography (2-24 hours) reduces reinfarction and recurrent ischemia. 1

Avoid very early angiography (<2 hours) after fibrinolysis unless rescue PCI is needed, as pooled analysis suggests potential harm from immediate intervention. 1