Within 4.5 hours of onset, what therapy improves outcome in acute ischemic stroke, and what are key exclusion criteria?

• A. Intravenous thrombolysis with alteplase; exclusions include noncontrast CT showing intracranial hemorrhage, suspicion of subarachnoid hemorrhage, active internal bleeding or coagulopathy (platelets <100,000, INR >1.7), recent major surgery or trauma, uncontrolled severe hypertension, and other high bleeding risks.
• B. Intra-arterial thrombectomy within 6 hours; no imaging exclusions.
• C. Aspirin within 24 hours; no exclusions.
• D. Cooling therapy within 3 hours; requires normal imaging.

Answer: (A)

Rapid reperfusion with intravenous alteplase within 4.5 hours of stroke onset improves outcome by dissolving the occlusive clot and limiting brain tissue damage, so saving function the sooner it’s given. Alteplase activates plasmin to break down fibrin and restore blood flow, with the greatest benefit when started as early as possible.

Safety hinges on avoiding bleeding. A noncontrast CT that shows bleeding or a suspicion of subarachnoid hemorrhage means alteplase should not be given. Bleeding risk is also increased by active internal bleeding or a coagulopathy: very low platelets (for example, under 100,000) or an elevated INR (over about 1.7) are exclusions. Recent major surgery or trauma raises the risk of hemorrhage and thus excludes thrombolysis. Uncontrolled severe hypertension must be brought under control before starting treatment, since very high blood pressure raises the chance of hemorrhagic transformation. There are other high-bleeding-risk situations as well.

The other therapies listed don’t align with the window or the risk considerations in the same way. Intracranial thrombectomy is a separate option for certain large vessel occlusions, but it isn’t the standard within 4.5 hours for all patients and involves different eligibility criteria. Aspirin early after stroke isn’t the recommended acute reperfusion strategy within this 4.5-hour window, and cooling therapy is not a routine, guideline-supported acute treatment, especially without appropriate imaging and indications.