The finding may be important in determining which patients will not respond well in the long term to IV medication, researchers said. These patients may benefit from additional therapy instead, they said.
The IV recombinant tissue plasminogen activator (rt-PA) alteplase is the only drug approved for treatment of acute ischaemic stroke, but not all patients respond well to it.
Other techniques have shown promise in such patients, but clinicians need to know which patients will not respond to rt-PA treatment before opting for these alternatives.
Up until now, it has proved difficult to identify early enough which patients will respond to rt-PA therapy.
In the study, the team analysed 120 patients with acute ischaemic stroke who were treated with IV rt-PA.
One in five (18.3 per cent) patients showed very early neurologic improvement (VENI) as measured by the National Institute of Health stroke scale.
After three months, 68.2 per cent had favourable outcomes. This compared with 29.6 per cent of patients who did not respond to IV treatment.
Similarly, asymptomatic brain bleeding occurred in 9.1 per cent of patients. But this rose to 23.5 per cent of patients without early improvement.
The researchers concluded: 'Our results suggest that VENI, as determined by a clinical routine tool at a patient's bedside, might help to rapidly select patients who will not respond to IV rt-PA but who could be candidates for bridging (alternative) therapy.'