The generalizability of the DEFUSE 3 trial held up in a secondary analysis showing that late endovascular thrombectomy was beneficial for a broad patient population with acute ischemic stroke.
Predictors of better functional outcome at 90 days were younger age, lower baseline stroke severity, and lower serum glucose level among the 182 patients with evidence of salvageable tissue on brain perfusion imaging who were randomized in the trial.
However, endovascular therapy in the 6- to 16-hour time window still improved functional outcomes more than medical therapy did after accounting for these variables (adjusted OR 3.1, 95% CI 1.8-5.4), according to Maarten Lansberg, MD, PhD, of Stanford Stroke Center in Palo Alto, California, and fellow DEFUSE 3 investigators reporting online in JAMA Neurology.
Furthermore, this treatment effect was not modified by age, symptom severity, time to randomization, imaging modality, nor location of the arterial occlusion.
“However, this uniform proportional benefit does not imply that there also is a uniform absolute benefit,” the authors cautioned.
“For example, patients with low NIHSS [NIH Stroke Scale] scores experienced a substantial absolute benefit in their chance of achieving functional independence but had no reduction in mortality, whereas patients with high NIHSS scores experienced a very limited benefit in functional independence but did have a reduction in mortality and severe disability,” the researchers said.
That time didn’t modify the benefit of stroke thrombectomy shouldn’t be used to justify treating late-presenting patients with less urgency either, Lansberg’s group emphasized.
“Since the ischemic core grows with time (albeit slowly in some instances) and the penumbra thus shrinks with time, a patient’s chance of having a substantial volume of salvageable tissue that fulfills criteria for late-window endovascular therapy decreases if imaging is delayed,” the team said.
Another group recently reported that reperfusion success after mechanical thrombectomy grew less likely with every passing hour from hospital arrival to groin puncture.
DEFUSE 3 investigators reported their main findings in early 2018. Study participants were a median age of 70 and scored a 16 on the NIH Stroke Scale. The group was evenly split between the sexes.
“Owing to the small sample size of this study, a pooled analysis of late time window endovascular stroke trials is needed to confirm these results,” according to Lansberg and colleagues, adding that their data may also not be applicable to patients older than 90 or elderly patients with pre-existing disability who were excluded from the trial.
The study was funded by grants from the National Institute for Neurological Disorders and Stroke.
Lansberg disclosed no conflicts of interest.
Several co-authors reported significant ties to industry.