Key Points:
- Meta-analysis looks at short-term outcomes with endovascular therapy plus IV thrombolysis vs IV thrombolysis alone for acute ischemic stroke
- Functional neurological outcomes at 3 months better when endovascular therapy added
Adding endovascular treatment—mechanical thrombectomy in particular—to IV thrombolysis improves functional neurological outcomes 3 months after an acute ischemic stroke, affirms a meta-analysis published online July 2, 2015, ahead of print in the Journal of NeuroInterventional Surgery.
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The Take Home Imaging will soon facilitate better selection of stroke patients for endovascular therapy, but “we still don’t have a really good understanding of the detailed nuances of how we do that,” Dr. Michael Hill says. |
Alberto Falk-Delgado, MD, PhD, of Uppsala University Hospital (Uppsala, Sweden), and colleagues pooled data from 6 recent trials comparing IV thrombolysis with or without endovascular therapy in which at least two-thirds of participants actually received IV thrombolysis.
The trials—MR CLEAN, IMS-III, EXTEND-IA, ESCAPE, SWIFT PRIME, and REVASCAT—randomized 1,943 patients, although the main analysis excluded the subgroup of IMS-III patients who did not have vessel occlusion confirmed with imaging. Endovascular therapy mostly consisted of thrombectomy, but intra-arterial thrombolysis was used also in MR CLEAN.
Median or mean patient age ranged among the trials from 65 to 71 years, and the median NIH Stroke Scale score varied from 13 to 18. Five of the trials included patients with stroke symptoms originating in the anterior circulation (IMS-III included anterior and posterior occlusions).
Short-term Advantage Shown
At 90 days, the patients who received endovascular therapy in addition to IV thrombolysis were more likely to have a functional neurological outcome (primary outcome; modified Rankin Scale [mRS] 0-2), with a number needed to treat of 6. Several secondary outcomes favored endovascular therapy as well (table 1).
Table 1. Functional Outcomes at 90 Days
|
|
Endovascular Therapy + IV Thrombolysis |
IV Thrombolysis Alone |
OR (95% CI) |
|
mRS Score 0-2 |
46% |
28% |
2.21 (1.78-2.74) |
|
mRS Score 0-1 |
29% |
14% |
2.46 (1.89-3.22) |
|
mRS Score 0-3 |
62% |
43% |
2.15 (1.75-2.64) |
|
Death |
15% |
20% |
0.73 (0.56-0.96) |
|
Severe Disability/Death |
23% |
33% |
0.58 (0.46-0.73) |
Abbreviation: mRS, modified Rankin Scale.
The 90-day rate of symptomatic intracerebral hemorrhage was 5% in each group (OR 1.05; 95% CI 0.65-1.68).
A sensitivity analysis that excluded IMS-III because of the limited use of stent retrievers in the trial provided similar results, although the difference in mortality was no longer significant.
Recent Trials Redeem Endovascular Therapy
Early trials failed to show a benefit of adding endovascular therapy to IV thrombolysis, but recent trials—starting with MR CLEAN, which was reported late last year—have consistently shown an advantage for percutaneous treatment, which has almost exclusively been performed with stent retrievers.
The authors note that the trials included in the meta-analysis differ in several ways, including the percentage of patients who received mechanical thrombectomy (just 39% in the IMS-III intervention group), time to intervention, and types of thrombectomy devices used.
They caution against generalizing the results of the meta-analysis because “included patients in these trials were a highly selected group and represent a small fraction of all stroke patients. Only 5%–13% of all stroke patients present to hospital within the time window for thrombolysis.”
Also, 5 of the 6 trials were stopped early, and premature termination has been shown to overestimate effect size, the authors point out.
Future studies of endovascular therapy, Dr. Falk-Delgado told WLNCMD in an email, need to evaluate longer-term outcomes, subgroups of patients who might derive the most benefit, the best ways to select patients using clinical and radiological criteria, and patients with vessel occlusions in the posterior brain circulation. An additional question, he said, is whether patients who are not eligible for IV thrombolysis might improve with thrombectomy using modern stent retrievers.
Imaging to Enable Patient Selection
In a telephone interview with WLNCMD, Michael D. Hill, MD, MSc, of Foothills Medical Center (Calgary, Canada), said that the meta-analysis provides insight into the size of the beneficial effect of endovascular therapy, pointing out that its advantage was already known and incorporated into guidelines.
A lesson from the recent positive trials is the importance of imaging, said Dr. Hill, who was the principal investigator of ESCAPE. “What we are going to come to in stroke is the careful use of imaging to pick the patients who should be offered this therapy, [but] we still don’t have a really good understanding of the detailed nuances of how we do that,” he added.
Future research also needs to explore the effects of treatment within various time windows and the possibility of skipping IV thrombolysis before taking patients directly to the cath lab, he said.
And although there is not much question that endovascular therapy is cost-effective, Dr. Hill reported, economic analyses will be needed to quantify that value. He noted that an upcoming study will show that endovascular therapy is more cost-effective than dialysis and other routine medical interventions.
Source:
Falk-Delgado A, Söderqvist ÅK, Fransén J, Falk-Delgado A. Improved clinical outcome 3 months after endovascular treatment, including thrombectomy, in patients with acute ischemic stroke: a meta-analysis. J NeuroIntervent Surg. 2015;Epub ahead of print.
Disclosures:
- Dr. Falk-Delgado reports no relevant conflicts of interest.
- Dr. Hill reports receiving grant funding through his institution from Covidien (now Medtronic) for the ESCAPE trial.
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