A 58-year-old man presents to the emergency department with acute anterior wall ST-elevation myocardial infarction (STEMI) of 2 hours duration. He has no contraindications to fibrinolytic therapy and is at a non-PCI-capable hospital. Which is the drug of choice for immediate reperfusion?

Explanation

## Fibrinolytic Therapy in STEMI **Key Point:** Alteplase (tissue plasminogen activator, tPA) is the preferred fibrinolytic agent for acute STEMI when primary PCI is not available within 120 minutes of first medical contact. ### Mechanism of Action Alteplase is a serine protease that directly activates plasminogen to plasmin, which then degrades fibrin clots. It is fibrin-selective and has high specificity for thrombi, minimizing systemic fibrinolysis compared to non-selective agents. ### Dosing & Administration - **Initial bolus:** 15 mg IV over 1–2 minutes - **Infusion:** 0.75 mg/kg over 30 minutes (max 50 mg) - **Second infusion:** 0.5 mg/kg over 60 minutes (max 35 mg) - Total dose should not exceed 100 mg ### Comparison of Fibrinolytic Agents | Agent | Fibrin-Selectivity | Reperfusion Rate | Intracranial Hemorrhage | Notes | |-------|-------------------|------------------|------------------------|-------| | **Alteplase (tPA)** | High | 50–60% | 0.6–0.9% | First-line; most studied | | Streptokinase | Low | 45–50% | 0.3–0.5% | Non-selective; antigenic | | Reteplase | Intermediate | 55–60% | 0.7–0.8% | Bolus dosing; less convenient | | Tenecteplase | High | 55–60% | 0.9–1.0% | Weight-based bolus; easier dosing | **High-Yield:** Alteplase is the **gold standard** fibrinolytic in most international guidelines (ACC/AHA, ESC) and is the most commonly tested agent in NEET PG. ### Clinical Pearl Fibrinolytic therapy should be administered **within 30 minutes of hospital arrival** ("door-to-needle" time) to maximize myocardial salvage. Alteplase achieves TIMI 3 flow in approximately 50–60% of patients. ### Adjunctive Therapy - **Dual antiplatelet therapy:** Aspirin + clopidogrel (or prasugrel/ticagrelor) - **Anticoagulation:** Unfractionated heparin or enoxaparin - **Beta-blocker:** For rate control and cardioprotection - **ACE inhibitor:** For ventricular remodeling prevention **Warning:** Do not confuse fibrinolytic agents with antiplatelet agents (clopidogrel) or beta-blockers (metoprolol) — these are adjunctive, not primary reperfusion therapy. [cite:Harrison 21e Ch 297]