How effective is fibrinolytic therapy 3-4.5 hours after symptom onset in ischemic stroke?

Updated: May 27, 2020
  • Author: Edward C Jauch, MD, MS, FAHA, FACEP; Chief Editor: Helmi L Lutsep, MD  more...
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In a meta-analysis of nine major trials of fibrinolysis treatment involving a total of 6756 patients with acute ischemic stroke, researchers found that administration of alteplase within 4.5 hours of stroke onset significantly improved outcomes, irrespective of age or stroke severity, with earlier treatment providing the greatest benefit. Good outcome was defined as modified Rankin score of 0 or 1, which indicates little or no residual disability at 3–6 months. The odds of a good stroke outcome were 75% higher for patients who received alteplase within 3 hours of symptom onset compared with those who did not. Patients given alteplase 3 to 4.5 hours after symptom onset had a 26% increased chance of a good outcome, and patients with a delay of more than 4.5 hours in receiving alteplase treatment had a nonsignificant 15% increase in the chance of a good recovery. [87, 88]

A 10-center European study of nearly 6900 patients found IV rt-PA to be most effective when given within 90 minutes of the onset of stroke symptoms. [89, 90] Patients scoring in the 7–12 range on the NIHSS had better outcomes when fibrinolytic therapy was provided within 90 minutes of symptom onset than when it was provided 90–270 minutes after onset. For patients with minor stroke or moderate-to-severe stroke, however, treatment within the initial 90-minute window provided no additional advantage.

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