Extending the Treatment Window for Thrombolysis in Acute Ischemic Stroke: Fan Z. Caprio, MD

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"Now the evidence is telling us that we can think about expanding that time window to those presenting outside of 4 and a half hours, if their tissue imaging, either MRI or CT, demonstrates that there is brain to be saved."

Acute ischemic stroke care continues to evolve as clinicians seek strategies to expand eligibility for reperfusion therapies without compromising safety. Intravenous thrombolysis with alteplase or tenecteplase remains a cornerstone of medical management, yet historically, rigid time-based criteria have limited the proportion of patients able to receive treatment. As imaging capabilities and trial data have advanced, the field is increasingly focused on tissue viability and individualized decision-making rather than strict clock-based cutoffs. This shift has important implications for neurologists practicing in both comprehensive stroke centers and community settings.

The 2026 American Heart Association/American Stroke Association (AHA/ASA) stroke guidelines formally endorse an extended time window for intravenous thrombolysis in select patients with acute ischemic stroke.¹ In addition to recognizing tenecteplase and alteplase as acceptable, largely equivalent options in the traditional 4.5-hour window, the guidelines support thrombolytic treatment beyond 4.5 hours and up to 24 hours from last known well in appropriately selected patients.

Advanced imaging now plays a central role in identifying those with limited irreversible injury and substantial salvageable tissue. This imaging-based approach may represent a significant paradigm shift, reframing the decision from “time is brain” to “tissue is brain” in eligible patients.

In a recent NeurologyLive^® interview, vascular and stroke neurologist Fan Z. Caprio, MD, associate professor of neurology at Northwestern University Feinberg School of Medicine, discussed key takeaways from the new guideline recommendations. She outlined how equivalence between alteplase and tenecteplase in 4.5 hours, the emphasis on minimizing delays before initial treatment, and the incorporation of MRI- or CT-based selection criteria beyond 4.5 hours could expand access to thrombolysis for patients who previously would have been excluded. Her commentary provides clinicians with a concise, practice-oriented lens on how these recommendations may reshape acute stroke workflows and patient selection in the coming years.

REFERENCES
1. Prabhakaran S, Gonzalez NR, Zachrison KS, et al. 2026 Guideline for the Early Management of Patients With Acute Ischemic Stroke: A Guideline From the American Heart Association/American Stroke Association. Stroke. Published online January 26, 2026. doi:10.1161/STR.0000000000000513