The most informative prognostic marker was a greater than 30% postprocedural improvement in NIHSS score.
Rapid clinical improvement following mechanical thrombectomy for acute ischemic stroke is a good indicator of long-term recovery, according to research published online May 22, 2019, ahead of print in Stroke.
“The prognosis of patients treated with mechanical thrombectomy for acute large vessel occlusion depends mostly on the grade of reperfusion,” co-author Xabier Urra, MD, PhD, and senior author Ángel Chamorro, MD, PhD (both from University of Barcelona, Spain), told Neurovascular Exchange in a joint email. “However, up to one-third of patients with complete reperfusion do not achieve functional independence at 3 months. Therefore, other early prognostic factors are warranted in patients treated with mechanical thrombectomy.”
The investigators, who were led by Salvatore Rudilosso, MD (University of Barcelona), studied a cohort of 423 patients with anterior circulation stroke treated with mechanical thrombectomy. Of these, 79% achieved a good outcome, defined as 90-day mRS 0-2. NIHSS scores were assessed prior to thrombectomy, at the end of the procedure (day 0), at day 1, and at day 7 or discharge.
The researchers examined the predictive value for good 90-day outcome using different cutoffs for absolute and percentage changes in the NIHSS score at each assessment. They then calculated the corresponding most-informative cutoffs to define substantial clinical improvement over time. Overall, the most informative cutoffs to define substantial clinical improvement were a greater than 30% rise in NIHSS at day 0, 40% at day 1, and 70% at day 7.
Next, patients were classified into subgroups of substantial clinical improvement according to the time from mechanical thrombectomy (day 0, 1, or 7). In the whole cohort, substantial clinical improvement was seen in 172 patients (40.7%) at day 0, in 76 patients (18.0%) at day 1, and in 17 patients (4.0%) at day 7. The investigators then calculated the adjusted odds ratio for good outcome for each group compared with the 158 patients who showed no substantial clinical improvement.
At each time point, clinical improvement was associated with better chance of a good outcome:
- Day 0: adjusted OR 47.4 (95% CI 22.1-101.7)
- Day 1: adjusted OR 27.7 (95% CI 11.8-65.0)
- Day 7: adjusted OR 12.6 (95% CI 3.8-41.4)
Multivariate analysis revealed that independent factors predicting substantial clinical improvement at day 0 were successful reperfusion (OR 25.79; 95% CI 12.92-51.47) and shorter time to groin puncture (OR per hour 0.90; 95% CI 0.85-0.96).
Potential Prognostic Marker and Clinical Endpoint
“The results of our study demonstrate that the delay to clinical improvement is inversely correlated to functional independence at 3 months, and early clinical improvement at the end of mechanical thrombectomy is an even stronger prognostic marker than the grade of reperfusion,” Urra and Chamorro wrote to NVX. “A substantial clinical improvement, defined as a > 30% decrease in NIHSS score at the end of mechanical thrombectomy, could represent not only a reliable prognostic marker but also a new clinical endpoint for research purposes.
“We think our findings could be helpful primarily to provide information to caregivers,” they continued. “But in the future, substantial clinical improvement and the grade of reperfusion could be used for the selection of patients that might benefit from new neuroprotective therapies.”
Commenting on the study for NVX, Jeremy J. Heit, MD, PhD (Stanford University School of Medicine, Stanford, CA), noted that the findings are consistent with the , in which patients who experienced rapid neurologic improvement 24 hours after thrombectomy were highly likely to have a good outcome.
“This study expands this idea further by examining a larger group of patients treated in earlier and more varied time windows and by looking at changes in patient symptoms over additional time points,” Heit said. “It is important to see the DEFUSE 3 results validated further in a larger and more heterogeneous cohort of patients.”
One thing, though, that “needs further investigation is why different patients who undergo successful thrombectomy with an excellent reopening of the blocked cerebral arteries might have different outcomes,” Heit continued, adding that he and his research team are currently exploring this very question and hope to have some answers published soon.
Rudilosso S, Urra X, Amaro S, et al. Stroke. 2019;Epub ahead of print.
Rudilosso, Urra, and Chamorro report no relevant conflicts of interest.
Heit reports being a consultant for MicroVention and Medtronic as well as a member of the medical and scientific advisory board for iSchemaView.