The results challenge current AHA guidelines and show highest recanalization rates in those treated at 16-24 hours.
Many patients with emergent large-vessel occlusion (ELVO) strokes can and do respond just as well to thrombectomy when treated outside the 6-hour window recommended by the American Heart Association (AHA) as when treated within this window, new observational data show.
The findings come from a real-world analysis of the North American Solitaire Stent Retriever Acute Stroke (NASA) and Trevo Stent-Retriever Acute Stroke (TRACK) registries published online September 15, 2018, ahead of print in the Journal of NeuroInterventional Surgery.
“The latest AHA guidelines state that only patients eligible for the DAWN and DEFUSE 3 studies should be treated with thrombectomy beyond 6 hours of stroke onset,” lead author Maxim Mokin, MD (University of South Florida, Tampa), told Neurovascular Exchange in an email. “We therefore aimed to evaluate the results of real-world experience using data sets from two large registries to determine outcomes in patients treated with thrombectomy beyond 6 hours of symptom onset.”
Mokin said his group “hypothesized that even when not adhering to very strict selection criteria used in DAWN or DEFUSE 3, patients can still achieve high rates of good clinical outcomes at 3 months.”
Mokin and colleagues conducted a pooled analysis of individual patient data from all 830 cases of anterior circulation acute ischemic stroke in the NASA and TRACK registries. Of these, 271 patients (32.7%) underwent thrombectomy beyond the first 6 hours of symptom onset.
Comparing patients who received thrombectomy within the 6-hour window with those who received thrombectomy at 6 to 16 hours and 16 to 24 hours after symptom onset revealed similar rates of good clinical outcome, mortality, and symptomatic intracranial hemorrhage (ICH). Surprisingly, rates of successful recanalization were actually highest among patients treated between 16 and 24 hours after symptom onset.
Outcomes Based on Time From Symptom Onset to Thrombectomy
|
|
0-6 Hours (n = 559) |
6-16 Hours (n = 248) |
16-24 Hours (n = 20) |
P Value |
|
90-Day mRS |
48.1% |
46.2% |
38.9% |
0.8 |
|
Mortality |
20.6% |
21.6% |
33.3% |
0.6 |
|
Symptomatic ICH |
8.0% |
10.9% |
5.0% |
0.5 |
|
TICI 2b/c |
79.4% |
72.6% |
85% |
0.04 |
A Challenge to Current Guidelines
“Our findings challenge the latest AHA guides and suggest that thrombectomy may be beneficial in patients with ELVO who present beyond 6 hours of symptom onset, even if DAWN or DEFUSE 3 criteria are not used for patient selection,” noted Mokin.
He did acknowledge some important limitations of the study, however. Notably, “in both registries, each participation site used its own selection criteria, thus we could not determine exact clinical (such as NIHSS severity) or imaging criteria (CT ASPECTS vs MRI vs CT perfusion) that are optimal for patient selection outside of the 0- to 6-hour window,” he pointed out.
The remaining critical unanswered question, said Mokin, is how wide the selection criteria should be for treatment of acute ischemic stroke with thrombectomy outside currently approved timing guidelines and at what point it might even be harmful.
Source:
Mokin M, Abou-Chebl A, Castonguay AC, et al. Real-world stent retriever thrombectomy for acute ischemic stroke beyond 6 hours of onset: analysis of the NASA and TRACK registries. J NeuroIntervent Surg. 2018;Epub ahead of print.
Disclosures:
Mokin reports being a consultant for Cerebrotech and speaker for Penumbra and Canon Medical.
