Endovascular thrombectomy benefits patients with ischemic stroke, mismatch imaging

Among patients with ischemic stroke and mismatch imaging profiles, the performance of endovascular thrombectomy correlated with improvements in clinical outcomes, according to a study published in JAMA Neurology.

“Our aims were to assess the data from all six clinical trials among patients enrolled beyond 6 hours after they were last known well (defined as the time at which the patient was last known to be without the symptoms of the current stroke) using the same perfusion imaging software program and to evaluate the treatment benefit among three subgroups: (1) patients who met the clinical imaging mismatch profile used in the DAWN study (clinical mismatch subgroup), (2) patients who met the target perfusion imaging mismatch profile used in the DEFUSE 3 study (target perfusion mismatch subgroup), and (3) patients with an undetermined imaging mismatch profile (undetermined profile subgroup, ie, patients for whom the imaging profiles could not be determined because a technically adequate CT or MRI perfusion study was not performed),” Gregory W. Albers, MD, of the department of neurology and neurological sciences and Stanford Stroke Center at Stanford University, and colleagues wrote.

Albers and colleagues used the AURORA Collaboration to pull data from published randomized clinical trials (RCTs) that included patients with anterior circulation ischemic stroke who were randomized between 6 hours and 24 hours after they were last known well and received treatment with second-generation neuro-thrombectomy devices. They identified 505 eligible patients from six studies and randomly assigned 266 patients (mean age, 68.4 years) to endovascular thrombectomy and 239 patients (mean age, 68.7 years) to the control group receiving standard care. Reduction in disability as measured by the modified Rankin Scale at 90 days served at the primary outcome.

The investigators also assessed whether the therapeutic response was different based on imaging profile among patients who received treatment based on the time when they were last known well. Researchers evaluated treatment benefits in a clinical mismatch subgroup, a target perfusion mismatch subgroup and an undetermined profile subgroup. Among these subgroups, Albers and colleagues evaluated the primary endpoint and during three treatment intervals (tercile 1, 6-9.5 hours; tercile 2, 9.6-12.7 hours; and tercile 3, 12.8-24 hours).

“Among 295 patients in the clinical mismatch subgroup and 359 patients in the target perfusion mismatch subgroup, [endovascular thrombectomy (EVT)] was associated with reductions in disability at 90 days vs. no EVT (clinical mismatch subgroup, odds ratio [OR] = 3.57; 95% CI, 2.29-5.57; target perfusion mismatch subgroup, OR = 3.13; 95% CI, 2.1-4.66),” Albers and colleagues wrote.

Albers and colleagues observed benefits in all three terciles for both subgroups. The highest OR was noted in tercile 3 (clinical mismatch subgroup, OR = 4.95; 95%CI, 2.2-11.16; target perfusion mismatch subgroup, OR = 5.01; 95% CI, 2.37-10.6). The investigators reported that 132 patients had an undetermined imaging profile; these patients had no significant treatment benefit (OR = 1.59; 95% CI, 0.82-3.06). Albers and colleagues noted a correlation between treatment effects for the clinical and target perfusion group compared with the undetermined profile subgroup (OR = 2.28; 95% CI, 1.11-4.7).

“The data from this pooled analysis suggest that receipt of EVT during an extended period after symptom onset is associated with similar benefit among patients with a clinical mismatch profile and those with a target perfusion mismatch profile throughout the 6- to 24-hour treatment interval,” Albers and colleagues wrote. “In the DEFUSE 3 clinical trial, which used the target perfusion mismatch profile for selection, patients did not receive treatment beyond 16 hours. However, in the DAWN clinical trial, which used the clinical mismatch criteria, patients received treatment for up to 24 hours. To our knowledge, this study provides the first data on the benefits of endovascular therapy among patients with a target perfusion mismatch profile beyond 16 hours after they were last known well. The associated benefits for these patients were substantial.”

In a related editorial, Jean-Claude Baron, MD, ScD, of the department of neurology at Saint Anne Hospital Center, University of Paris, France, said Albers and colleagues’ findings were clear in that thrombectomy correlated with equal benefits between patients with the two imaging mismatch profiles for the 6- to 24-hour interval and the entire tertial. Baron noted the target mismatch profile could be applied to both the 6- to 16-hour interval and the 16- to 24-hour interval.

“The main results presented by Albers et al. appear to document that the use of either mismatch profile for the selection of patients for thrombectomy is associated with equivalent benefit across the entire 6- to 24-hour window,” Baron wrote. “Applying this finding to routine care would substantially increase the currently small proportion of patients presenting more than 6 hours after stroke onset who could receive this beneficial and reasonably safe therapy. This particularly applies to the patients in the 16- to 24-hour window who fulfill the target mismatch criteria, which are more inclusive than the clinical mismatch criteria. Therefore, it seems sensible that the results of the Albers et al. study, and their implications, would be implemented in forthcoming international guidelines.”