A potential new era for acute stoke imaging-based selection, treatment

In a recent editorial published in the November issue of The New England Journal of Medicine (NEJM), Werner Hacke, MD, PhD, DSc, discussed a new era of imaging selections for patients who are looking to benefit from a thrombectomy performed long after the onset of a stroke.

In response to recent findings from the DAWN trial published by the NEJM, Hacke asserted that patients who have severe stroke, vascular occlusion and penumbral tissue choosing to have a thrombectomy long after experiencing a stroke is far more effective than what current guidelines suggest.  

"The DAWN trial gives us hope that trials investigating the use of late intravenous thrombolysis that require the presence of ischemic tissue might have positive outcomes," Hacke explained in his editorial. 

The DAWN trial (DWI or CTP Assessment with Clinical Mismatch in the Triage of Wake-Up and Late Presenting Strokes Undergoing Neurointervention with Trevo) is a second step in investigating endovascular mechanical thrombectomy for the treatment of acute ischemic stroke, according to Hacke. Unlike its precursor, the "MR CLEAN" trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), the DAWN trial takes one step further in confirming the efficacy of thrombectomy performed within six hours after a stroke in patients with occlusion of a cerebral large vessel.  

All 206 patients who participated in the DAWN trial had occlusion of a large cerebral vessel in the brain that presented between six and 24 hours after the onset of stroke. Additionally, 107 patients were randomly assigned to a thrombectomy plus standard care group and the 99 other patients in a control group assigned to standard care alone, according to study methods.  

"Among patients with acute stroke who had last been known to be well six to 24 hours earlier and who had a mismatch between clinical deficit and infarct, outcomes for disability at 90 days were better with thrombectomy plus standard care than with standard care alone," according to study results.  

Furthermore, all 206 patients underwent successful thrombectomy and 60 percent of them had their first stroke symptoms when they woke up, concluding that the time of stroke onset was not known, according to Hacke. 

In response to the DAWN trial, Hacke poses the question: How do the results of the DAWN trial compare with results of other trials of thrombectomy for stroke, such as those included in the meta-analysis?

Hacke argues that the approach of the DAWN trial and other similar trials in identifying brain tissue at risk for infarction resulted in the highest rates of functional independence ever reported with thrombectomy.  

"In the DAWN trial, the rate of the second primary end point of functional independence at 90 days was 49 percent, and in the meta-analysis, the rate was 46 percent; 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. However, it is also worth emphasizing that the 13 percent rate of functional independence in the control group in the DAWN trial was lower than the 26 percent rate in the control group in the pooled analysis," Hacke said. "This low rate of functional independence is probably the best we can expect for patients with severe stroke who have occlusion of a large vessel that has not been recanalized by 24 hours after stroke onset."

Conclusively, Hacke leaves readers with his belief that the results of the DAWN trial do not support a "general liberalization of the time window" for thrombectomy or thrombolysis and ultimately agrees that reducing the time between one having a stroke to reciting treatment produces the best outcomes for the patient.