Should the Time Window Be Expanded?
By selecting patients who had a region of brain that was poorly perfused, but not yet infarcted, Dr. Jovin and colleagues replaced the conventional six-hour time window for stroke treatment with a “tissue window,” said Werner Hacke, MD, PhD, Chair of the Department of Neurology at the University of Heidelberg in Germany, in an accompanying editorial. The rate of functional independence at 90 days in the DAWN trial (49%) was similar to that in a previous meta-analysis of several trials of mechanical thrombectomy (46%). “These similar findings suggest that the use of a ‘tissue window’ in choosing patients for thrombectomy is as good as the use of a time window,” said Dr. Hacke. “However, it is also worth emphasizing that the 13% rate of functional independence in the control group in the DAWN trial was lower than the 26% rate in the control group in the pooled analysis.” This low rate of functional independence “is probably the best we can expect” for patients who have not had recanalization by 24 hours after stroke onset.
The DAWN trial provides reason to expect that trials investigating late IV thrombolysis that require the presence of ischemic tissue might have positive outcomes. But “the results of the DAWN trial do not support a general liberalization of the time window for thrombectomy or thrombolysis,” Dr. Hacke continued. “Reducing the time from the onset of stroke to treatment remains essential and results in the best outcomes.”
—Erik Greb
Suggested Reading
Nogueira RG, Jadhav AP, Haussen DC, et al. Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct. N Engl J Med. 2017 Nov 11 [Epub ahead of print].
Hacke W. A new DAWN for imaging-based selection in the treatment of acute stroke. N Engl J Med. 2017 Nov 11 [Epub ahead of print].
