The rtPA (Alteplase) 0- to 6-Hour Acute Stroke Trial, Part A (A0276g)

Abstract

Background and Purpose —The Thrombolytic Therapy in Acute Ischemic Stroke Study, which started in August of 1991, was designed to assess the efficacy and safety of intravenous rtPA (alteplase) in patients with acute (0 to 6 hours) ischemic stroke. In October 1993 enrollment was halted because of Safety Committee (DMSB) concerns. In December 1993 the time window was changed to 0 to 5 hours, and it was decided to restart enrollment as a separate study (part B). We report here the results of the original study (part A), focusing on evaluating the safety and efficacy of rtPA given between 0 and 6 hours after stroke onset. Methods —This investigation was a phase II, placebo-controlled, double-blind, randomized study utilizing 0.9 mg/kg IV rtPA or placebo over 1 hour, which was conducted at university and community sites in North America. Except for time to treatment, enrollment criteria were very similar to those of the NINDS rtPA stroke study. Primary efficacy end points were the number of patients with a decrease of 4 or more points on the National Institutes of Health Stroke Scale (NIHSS) at 24 hours and day 30, along with infarct volume at day 30. Secondary end points included mortality and functional recoveries on the Barthel Index and Modified Rankin scale at days 30 and 90. Results —A total of 142 patients were enrolled at 42 sites in North America, including 22 <3 hours (15%) and 46 between 5 and 6 hours (32%). The groups were well matched on baseline characteristics, including NIHSS (mean of 13 for both). For the primary end points, a higher percentage of rtPA patients had a 4-point improvement at 24 hours (placebo 21%, rtPA 40%; P =0.02); however, this early effect was reversed by 30 days, with more placebo patients having a 4-point improvement (75%) than patients treated with rtPA (60%, P =0.05). Treatment with rtPA significantly increased the rate of symptomatic intracerebral hemorrhage within 10 days (11% versus 0%, P <0.01) and mortality at 90 days (23% versus 7%, P <0.01). Conclusions —This study found no significant rtPA benefit on any of the planned efficacy end points at 30 and 90 days in patients treated between 0 and 6 hours after stroke onset. These negative results apply to patients treated after 3 hours, because only 15% of the patients were enrolled before 3 hours. The risk of symptomatic intracerebral hemorrhage was increased with rtPA treatment, particularly in patients treated between 5 and 6 hours after onset. These results do not support the use of intravenous rtPA for stroke treatment >3 hours after onset.