Use of Imaging to Select Patients for Late Window Endovascular Therapy

Gregory W. Albers, MD


Stroke. 2018;49(9):2256-2260. 

In This Article

Role of Noncontrast CT for Selecting Patients for Late Window Thrombectomy

Based on the large treatment effect seen in DEFUSE 3 and DAWN, it has been speculated that advanced imaging with CTP or MRI may not be required to select patients for late window thrombectomy. However, currently available data do not support the efficacy of late window thrombectomy for patients selected based on noncontrast CT. For example, in the HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) pooled analysis, in which the majority of patients were selected based on a noncontrast CT, often in conjunction with an ASPECT score, the treatment effect diminished over time and was no longer statistically significant just beyond 7 hours after symptoms onset.[14] In the MR CLEAN study (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), that used noncontrast CT alone for parenchymal imaging, treatment efficacy for achieving a favorable outcome (modified Rankin Scale score, 0–2) was lost when stroke onset to reperfusion was longer than 6 hours.[19]

The best data for extended window reperfusion in patients selected by ASPECT scores comes from the REVASCAT study (Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset) that randomized patients to thrombectomy up to 8 hours after onset if the CT ASPECT score was >6 or MR ASPECT score >5. This study showed a substantial reduction in treatment efficacy over time, and favorable outcome rates dropped dramatically for patients with ASPECT scores of 6 to 7.[20] Among these patients, even if reperfusion was achieved, favorable outcome (modified Rankin Scale score, 0–2 at 90 days) rates were <20% if reperfusion occurred >9 hours after the time the patient was last known to be well. In contrast, in DEFUSE 3, favorable outcome rates were 50% in patients who were treated between 9 to 12 hours after symptoms onset, and neither DEFUSE 3 or DAWN showed a decline in treatment effect up to the end of their treatment windows.[1,2]