Endovascular Stroke Therapy: Real-World Outcomes Improving

April 12, 2018

Endovascular therapy for patients with acute ischemic stroke in the real world is at least as effective and safe as in randomized clinical trials, a new registry study from the Netherlands suggests.

The study compared outcomes of patients in the MR CLEAN trial — the first successful randomized controlled trial of endovascular therapy — with outcomes in a registry of real-world patients receiving endovascular treatment for stroke in the MR CLEAN centers after the trial ended.

Results showed that a higher proportion of patients reached a good functional outcome after 90 days in the registry, despite older age and more comorbidities.

The study is published in the April 6 issue of BMJ.  

"After the MR CLEAN trial, which proved the efficacy of endovascular therapy in stroke, we started using this treatment routinely and all patients treated were entered into a registry so we could compare how outcomes in the real world compared with those in the clinical trial," lead author, Ivo Jansen, MD, Academic Medical Center, Amsterdam, the Netherlands, commented to Medscape Medical News.

"Our results suggest that outcomes are just as good — probably even better actually — in the real world," he said. "The percentage of patients achieving a good outcome was higher in the registry."  

Jansen said he believes the better outcomes in the registry were due to faster treatment times. "The time from stroke onset to treatment was faster in the registry study — by about 1 hour," he said, probably because more efficient systems of care have now been set up.

"The randomized trial was the first time we had focused on endovascular treatment for stroke and everyone was still learning how to do this," he added. "Now we are much more experienced — people know what to expect at all levels: interventionalists, nurses, paramedics, cath lab teams, we are all used to accelerating these patients through the system so they get treatment faster."

He noted that traditionally, results from real-world studies can be less impressive than those from randomized trials because the trials often have stricter inclusion criteria and high motivation levels from all involved.

"We did have a slightly broader population with a slightly higher mean age in the MR CLEAN registry compared to the randomized trial, and this suggests that the effect of the shorter time to treatment was so strong it overrode these other factors."

He concluded: "The MR CLEAN trial results were fantastic and established endovascular therapy as a proven treatment for stroke, but we always need clinical validation in the real world. Our trial really shows that stroke patients in routine clinical practice really benefit from this treatment and there may be room for even more benefit by improving our systems of care to shorten treatment times."

For the current study, the researchers analyzed data from 1488 patients undergoing endovascular therapy for acute ischemic stroke within 6.5 hours from onset of symptoms at 1 of 16 centers in the Netherlands between March 2014 and June 2016.

The primary outcome was the modified Rankin Scale (mRS) score, ranging from 0 (no symptoms) to 6 (death) at 90 days.

Results showed a statistically significant shift toward better functional outcome in patients in the MR CLEAN registry compared with the MR CLEAN trial intervention arm (adjusted common odds ratio [OR], 1.30; 95% confidence interval [CI], 1.02 to 1.67) and the trial control arm (OR, 1.85; 95% CI, 1.46 - 2.34).

Good functional outcome (mRS score of 0 - 2) was achieved in 37.9% of patients in the registry compared with 32.6% in the randomized trial intervention arm and 19.1% in the control arm.

The reperfusion rate, with successful reperfusion defined as a score of 2B-3 on the extended thrombolysis in cerebral infarction score, was 58.7%, the same as for patients in the MR CLEAN trial.

Duration from onset of stroke to start of endovascular treatment and from onset of stroke to successful reperfusion or last contrast bolus was 1 hour shorter for patients in the MR CLEAN registry.

Symptomatic intracranial hemorrhage occurred in 5.8% of patients in the registry compared with 7.7% in the randomized trial intervention arm and 6.4% in the control arm.

The researchers note that these outcomes are reported in a broad group of patients without imaging selection (apart from computed tomography angiography to confirm occlusion of proximal vessels), in contrast to the trend in current clinical trials to select patients before treatment with a favorable prognosis based on imaging characteristics. However, some patient selection probably also occurred in this registry because treatment decisions were based on individual considerations by doctors, they add.

"The MR CLEAN Registry elucidates that, despite much research over the past years, patient selection for endovascular treatment is still not applied in a structured manner in clinical practice, at least in the Netherlands," they write. "Despite this, patients' functional outcome improved substantially compared with the MR CLEAN trial. Research is needed to improve existing patient selection paradigms and tools, particularly those combining clinical and imaging variables, and to provide consensus on how patient selection for endovascular treatment can be reliably and consistently implemented."

The MR CLEAN registry is still ongoing and now has more than double the number of patients than reported in the current paper, Jansen said.

There are also a series of ongoing new randomized trials of endovascular treatment for stroke by the MR CLEAN group under the banner of MR CLEAN-2. These include a trial of endovascular therapy without thrombolysis, a study of late intervention (more than 6 hours from stroke onset), one in which nitroglycerin is given in the ambulance, and one investigating the use of periprocedural heparin and antiplatelet agents.

"These studies are all trying to find ways of achieving incremental benefits when endovascular treatment is used in stroke," he added.

This study was funded and carried out by the Erasmus University Medical Centre, the Academic Medical Centre Amsterdam, and the Maastricht University Medical Centre. The study was additionally funded by the Applied Scientific Institute for Neuromodulation. Jansen has disclosed no relevant financial relationships.

BMJ.  Published online March 9, 2018. Full text

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