April 19, 2015

GLASGOW, Scotland — Mechanical thrombectomy with a stent retriever system (Solitaire, Covidien) led to improved outcomes vs thrombolysis alone in patients with acute stroke caused by a proximal large-vessel occlusion treated within 8 hours in the REVASCAT trial.

REVASCAT is one of three new positive studies showing benefits of endovascular therapy in patients with stroke presented here at the inaugural European Stroke Organisation (ESO) Conference 2015. The other two studies presented here are THERAPY and THRACE.

These three studies add to four previous trials reported in the past few months (MR CLEAN, ESCAPE, EXTEND-IA, and SWIFT PRIME), all showing long-awaited success with endovascular therapy for acute stroke.

"We found a 15.8% absolute increase in the number of patients achieving functional independence, corresponding to a number needed to treat of six," said Antonio Davalos, MD, from the Hospital Universitari Germans Trias i Pujol, Barcelona, Spain, presenting the REVASCAT data at the ESOC opening session. Functional independence was defined as a modified Rankin Scale (mRS) score of 0 to 2.

The REVASCAT study was published online April 17 in the New England Journal of Medicine to coincide with its presentation here at the ESOC meeting.

Broadly Applicable

The REVASCAT trial included all but eight patients fulfilling the entry criteria treated at any of the endovascular centers in Catalonia, Spain, which Dr Davalos said demonstrated the generalizability of the therapy. "Our results apply to the whole target population in our country," he emphasized.

Jeffrey Saver, MD, from the University of California, Los Angeles, who led the SWIFT PRIME trial, said this was a key aspect of REVASCAT: "Because it captured practically all eligible patients in Catalonia, we can be sure it did not have any bias for who was recruited into the trial. So we know it is broadly applicable."

Dr Saver added that REVASCAT was more like MR CLEAN than SWIFT PRIME or ESCAPE, in that it enrolled a broader population and it did not use sophisticated imaging to select patients.

"REVASCAT had ASPECT scores lower than the other trials showing more severe abnormality on standard imaging," he said. "They also delayed endovascular therapy to make sure patients did not respond to tPA (tissue plasminogen activator). This fits in with lower rates of good outcomes than in the other studies, but they still showed an impressive benefit of thrombectomy."

 
We need a revolution for this. Dr Valeria Caso
 

Commenting for Medscape Medical News, session cochair Valeria Caso, MD, from the University of Perugia, Italy, said the REVASCAT trial was "further confirmation that we have to reorganize the pathway for acute stroke." She added: "We need to enhance endovascular treatment even for the small centers. We need a revolution for this."

For the REVASCAT trial, within 8 hours of the onset of symptoms of acute ischemic stroke, 206 patients were randomly assigned to either medical therapy (including intravenous alteplase when eligible) and endovascular therapy with the Solitaire stent retriever (thrombectomy group) or medical therapy alone.

All patients had confirmed proximal anterior circulation occlusion and the absence of a large infarct on neuroimaging. In all study patients, the use of alteplase either did not achieve revascularization or was contraindicated.

The trial was stopped early after 206 patients had been enrolled, following positive results for thrombectomy being reported from other similar trials.

Baseline characteristics showed that the median National Institute of Health Stroke Scale score was 17, the median Alberta Stroke Program Early CT Score (ASPECTS) was 7 in the thrombectomy group and 8 in the control group, and intravenous alteplase was administered to 68.0% of patients in the thrombectomy group and 77.7% of those in the control group. The median time from stroke onset to randomization was 225 minutes.

Results showed that thrombectomy reduced the severity of disability during the range of the mRS at 90 days, the primary endpoint, with an adjusted odds ratio of 1.7 (95% confidence interval [CI], 1.05 - 2.8).

Functional independence (mRS score, 0 - 2) occurred in 43.7% of the intervention group vs 28.2% of the control group (adjusted odds ratio, 2.1; 95% CI, 1.1 - 4.0).

Symptomatic intracranial hemorrhage occurred in 1.9% of patents in both groups, and mortality was 18.4% in the thrombectomy group and 15.5% in the control group (P = .60).

In the New England Journal of Medicine article, the authors say the "early nonsignificant increase in mortality in the thrombectomy group, as compared with the control group, can be explained by multiple potential factors, including thrombectomy-associated adverse events."

Is ASPECTS Enough?

In an accompanying editorial, Anthony J. Furlan, MD, from University Hospitals Case Medical Center, Cleveland, Ohio, notes that REVASCAT used ASPECTS to select patients with a large stroke.

"Although quick and easy to perform, it is unclear whether an ASPECTS alone is sufficient for predicting endovascular outcome because it only approximates core volume," he writes.

Dr Furlan also points out that it is also unclear how far the time window for endovascular treatment can be extended with the use of imaging selection criteria.

"Regardless, earlier is always better, because time is brain," He concludes. "Pending the resolution of this issue, it is probably best to avoid initiating endovascular therapy in patients with large (>50 to 70 ml) infarct cores as assessed by means of [computed tomography] or [magnetic resonance imaging] or an ASPECTS of 4 or less, beyond 6 hours from stroke onset."

The REVASCAT trial was supported by Fundació Ictus Malaltia Vascular through an unrestricted grant from Covidien, by a grant from the Spanish Ministry of Health cofinanced by Fondo Europeo de Desarrollo Regional (Instituto de Salud Carlos III, Red Temática de Investigación Cooperativa Invictus, and a grant from the Generalitat de Catalunya. Dr Davalos reports receiving grant and nonfinancial support from Covidien during the conduct of the study and personal fees from Covidien outside the submitted work. Dr Saver reports receiving personal fees from Covidien during the conduct of the SWIFT PRIME study; he is also an employee of the University of California, which holds a patent on retriever devices for stroke.

European Stroke Organisation (ESO) Conference 2015. Abstract 75. Presented April 17, 2015.

N Engl J Med. Published online April 17, 2015. Article full text, Editorial full text

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