MRI-Guided Intravenous Alteplase for Stroke — Still Stuck in Time

Time is a critical determinant of patient eligibility for intravenous thrombolysis in acute stroke. In such patients, intravenous alteplase is routinely administered up to 4.5 hours after the onset of symptoms, but even within this window, earlier treatment leads to better outcomes. Restriction of treatment to fixed times has limitations, since the time of symptom onset often cannot be ascertained, particularly in patients who wake up from sleep with a neurologic deficit. Furthermore, most patients arrive at the hospital more than 4.5 hours after symptom onset, which renders only a minority of patients eligible for treatment. The duration of symptoms . . .