A 68-year-old woman with a history of hypertension presents with acute homonymous hemianopia affecting the right visual field. Diffusion-weighted MRI confirms acute infarction in the left posterior cerebral artery territory involving the occipital lobe. What is the drug of choice for acute stroke management in this patient?

Explanation

## Acute Ischemic Stroke with Homonymous Hemianopia ### Clinical Presentation Homonymous hemianopia (loss of the same half of visual field in both eyes) with acute onset indicates posterior cerebral artery (PCA) territory infarction affecting the occipital lobe. This is a time-critical emergency requiring immediate reperfusion therapy. ### Drug of Choice: Alteplase (IV Thrombolysis) **Key Point:** Alteplase (tissue plasminogen activator, tPA) is the gold-standard first-line thrombolytic agent for acute ischemic stroke within the therapeutic window (4.5 hours from symptom onset). It has the strongest evidence base for improving neurological outcomes and visual field recovery. **High-Yield:** Alteplase mechanism: 1. Fibrin-specific serine protease 2. Converts plasminogen to plasmin 3. Dissolves thrombus and restores cerebral perfusion 4. Reduces infarct volume and improves functional recovery ### Acute Stroke Management Algorithm ```mermaid flowchart TD A[Acute ischemic stroke suspected]:::outcome --> B{Time from symptom onset?}:::decision B -->|< 4.5 hours| C[IV alteplase eligible?]:::decision B -->|4.5-24 hours| D[Mechanical thrombectomy if LVO]:::action B -->|> 24 hours| E[Antiplatelet monotherapy]:::action C -->|No contraindications| F[IV alteplase 0.9 mg/kg]:::action C -->|Contraindicated| G[Mechanical thrombectomy if LVO]:::action F --> H[Reperfusion & symptom improvement]:::outcome G --> H ``` ### Comparison of Acute Stroke Therapies | Agent | Mechanism | Window | Evidence | Indication | NNT | |-------|-----------|--------|----------|-----------|-----| | **Alteplase (IV tPA)** | Fibrinolytic | 0–4.5 hrs | Strongest (NINDS trial) | 1st-line acute ischemic stroke | 6–8 | | Aspirin | Antiplatelet | Any time | Weak (secondary prevention) | Not for acute phase | — | | Clopidogrel | Antiplatelet | Any time | Weak (secondary prevention) | Not for acute phase | — | | Warfarin | Anticoagulant | Days–weeks | Contraindicated acutely | Cardioembolic stroke (delayed) | — | **Clinical Pearl:** Aspirin and clopidogrel are antiplatelet agents used for *secondary prevention* after stroke, not for acute thrombolysis. They have no role in the hyperacute phase and may increase bleeding risk if given before thrombolysis is ruled out. **Warning:** Do NOT use anticoagulation (warfarin) in the acute phase of ischemic stroke — it increases hemorrhagic transformation risk. Anticoagulation is reserved for cardioembolic stroke after ruling out hemorrhage and typically started after 24–48 hours. **Mnemonic:** **THROMBOLYSIS** = **T**ime-critical, **H**igh-dose alteplase, **R**eperfusion within **O**pening window (4.5 hrs), **M**echanical backup if contraindicated, **B**lood pressure control, **O**utcome-driven, **L**arge vessel occlusion assessment, **Y**es to imaging first, **S**afe dosing, **I**V route, **S**troke center care. **Tip:** In exam questions on acute stroke with visual field defects, always choose IV alteplase if the time window is ≤4.5 hours and there are no contraindications (recent surgery, active bleeding, INR >1.7, platelet count <100K, glucose <50 or >400). Antiplatelet agents come *after* thrombolysis is given or ruled out. [cite:AHA/ASA Acute Ischemic Stroke Guidelines 2019]