Intravenous thrombolysis in ischemic stroke with unknown onset using CT perfusion

Background Acute ischemic stroke patients with unclear onset time presenting >4.5 h from last‐seen‐normal (LSN) time are considered late patients and excluded from i.v. thrombolysis. We aimed to evaluate whether this subgroup of patients is different from patients presenting >4.5 h from a witnessed onset, in terms of eligibility and response to computed tomography perfusion (CTP)‐guided i.v. thrombolysis. Methods We prospectively studied consecutive acute non‐lacunar middle cerebral artery (MCA) ischemic stroke patients presenting >4.5 h from LSN. All patients underwent multimodal CT and were considered eligible for i.v. thrombolysis according to CTP criteria. Two patient groups were established based on the knowledge of the stroke onset time. We compared the proportion of candidates suitable for intravenous thrombolysis between both groups, and their outcome after thrombolytic therapy. Results Among 147 MCA ischemic stroke patients presenting >4.5 h from LSN, stroke onset was witnessed in 74 and unknown in 73. Thirty‐seven (50%) patients in the first group and 32 (44%) in the second met CTP criteria for thrombolysis (P = 0.7). Baseline variables were comparable between both groups with the exception of age, which was higher in the unclear onset group. The rates of early neurological improvement (54.1% vs 46.9%), 2‐h MCA recanalization (43.5% vs 37%), symptomatic hemorrhagic transformation (3% vs 0%) and good 3‐month functional outcome (62.2% vs 56.3%) did not differ significantly between both groups. Conclusion Delayed stroke patients with unknown onset time were no different than patients >4.5 h regarding eligibility and response to CTP‐based i.v. thrombolysis.