Temporal profile of recanalization after intravenous tissue plasminogen activator -: Selecting patients for rescue reperfusion techniques

Background and Purpose - Intravenous thrombolysis in stroke achieves arterial recanalization in approximate to 50% of cases. Determining temporal profile of recanalization may address patient selection and potential benefits of further rescue reperfusion techniques. Methods - We studied 179 consecutive intravenous tissue plasminogen activator (t-PA)- treated patients with intracranial artery occlusion. Continuous transcranial Doppler assessed recanalization (none-partial-complete) at 60 minutes ( early), 120 minutes ( delayed) after t-PA bolus, and 6 hours ( late) from symptom onset. Outcomes were determined: National Institutes of Health Stroke Scale (NIHSS; 48-hour NIHSS) and 3-month modified Rankin Scale (mRS). Results - On admission, 68% of patients presented proximal middle cerebral artery occlusion, median NIHSS 17. Early recanalization was complete for 30 patients (17%), partial for 50 (28%), and none for 99 (55%). Delayed recanalization was complete for 56 patients (31%), partial for 39 (22%), and none for 84 (47%). Although early flow improvement was observed in up to 45% of patients, only 19% of patients with persistent occlusion (11% of total) presented delayed recanalization ( odds ratio [ OR] delayed/early recanalization, 0.16; 95% CI, 0.085 to 0.304; P < 0.001). Among patients with persistent occlusion at 2 hours, only 13 (7% of total) presented late flow improvement ( OR late/early recanalization, 0.09; 95% CI, 0.043 to 0.196; P < 0.001). The few patients with late recanalization presented comparable median 48-hour NIHSS to those with early/delayed recanalization ( 3 versus 4.5; P = 0.9) and much lower than those with persistent occlusion after 6 hours ( 3 versus 15; P = 0.005). At 3 months, the rate of mRS <= 2 was not statistically different between patients with early/delayed versus late recanalization ( 55% versus 86%; P = 0.12) but was lower if occlusion persisted 6 hours after onset ( 22%; P < 0.001). Conclusion - The majority of t-PA - induced recanalizations occur during the first hour after treatment. Recanalizations during the following hours are rare but still related to clinical improvement if achieved within 6 hours from onset. Rescue reperfusion techniques should be considered if flow improvement is not observed 60 minutes after t-PA bolus.