More Time for tPA Therapy
Can the window of time for giving tissue plasminogen activator (tPA) to patients with ischemic stroke safely be opened wider, from the standard three hours to six hours? Researchers from university hospitals in Hamburg, Heidelberg, and Cologne, Germany, suggest that instead of a one-size-fits-all approach based on clock time, it might be possible to tailor treatment to individual needs— with the help of magnetic resonance imaging (MRI).
They administered IV tPA within three hours to 108 patients and within three to six hours to 66 others. They then compared outcomes with those of pooled placebo patients and pooled tPA patients from three major stroke trials.
The extra effect of using MRI to select patients was “quite remarkable,” the researchers say. They found an 8% absolute increase of favorable outcome, compared with unselected tPA patients, and 14%, compared with placebo. Outcomes were not related to the onset-to-treatment time.
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Mortality rates were lower in the patients undergoing MRI (7.5%) than in both the pooled tPA group (13%) and the pooled placebo group (12%). Death after 90 days was also less likely in the MRI-selected tPA patients.
Why does MRI help? In one sample, the number of patients likely to benefit from thrombolysis wanes over time, as does the overall treatment effect. However, a high percentage of patients who have had an acute ischemic stroke have penumbral patterns beyond the first three hours; MRI might be able to help identify those patients whose tissue is at risk for infarction.
