What is the recommended window for IV alteplase in acute ischemic stroke, and what is a key exclusion?

• A. IV alteplase within 4.5 hours of onset; exclude intracranial hemorrhage, uncontrolled hypertension, recent surgery, bleeding risk; monitor BP and neurologic status closely
• B. IV alteplase within 24 hours; exclude hypertension
• C. IV alteplase within 6 hours; exclude diabetes
• D. IV alteplase within 1 hour; exclude age over 90

Answer: (A)

Timing matters for IV alteplase in acute ischemic stroke because the benefit of dissolving the clot declines with time. The recommended window for IV alteplase is within 4.5 hours of onset for eligible patients, after safety screening. A key safety screen is imaging to exclude intracranial hemorrhage; if hemorrhage is present, thrombolysis is contraindicated. This is why the option that states a 4.5-hour window and highlights intracranial hemorrhage as a major exclusion best fits current practice. Other timeframes, like 24 hours, 6 hours, or 1 hour, do not align with the established evidence and guidelines for routine IV alteplase use. Along with hemorrhage exclusion, other safety factors include uncontrolled hypertension, recent major surgery, and other bleeding risks, but intracranial hemorrhage on imaging is the critical determinant that prevents treatment.