Endovascular Benefit Finally Confirmed for Basilar Artery Stroke

May 06, 2022

The benefit of endovascular therapy in the treatment of stroke caused by an occlusion of the basilar artery has finally been confirmed in the ATTENTION randomized trial.

The study, conducted in China, showed that endovascular therapy for basilar artery occlusion is associated with higher rates of favorable and independent outcomes, as well as lower overall disability and lower mortality at 90 days, than best medical management alone.

The results were presented by Raul Nogueira, MD, professor of neurology at the University of Pittsburgh School of Medicine, Pennsylvania, at the European Stroke Organisation Conference (ESOC) 2022, where they were greeted with applause from the audience.

"We can finally say that we have conquered the basilar artery territory. It is about time. We can finally confirm that the benefit of endovascular therapy persists in the posterior circulation," Nogueira said.

"The disability reduction benefit of endovascular therapy for basilar artery occlusion appears to be within the same range as that observed in the anterior circulation. However, in contrast to most anterior circulation endovascular trials, the ATTENTION trial also demonstrated a potential benefit in terms of mortality," he added.

Nogueira explained that the first series of endovascular treatment for stroke in the modern era was published in 1988, and this was in the basilar artery occlusion territory, but almost 35 years later, although there has been overwhelming proof of benefit of endovascular treatment in the antiterror circulation, it remains unknown whether endovascular treatment is beneficial to treat acute basilar artery occlusion. This is despite efforts in conducting two trials — the BEST and BASICS trials — which showed a direction of benefit but failed to show real significance.

"Having said that, these trials paved the way for the current trial specifically by demonstrating the importance of consecutive recruitment, fast enrolment, and the minimalization of crossover. They also confirmed the ideal target population for these procedure in an individual patient level meta-analysis of these two trials," he said.

In addition, there have also been two large Chinese registries suggesting significant benefits.

The ATTENTION trial was conducted to evaluate the hypothesis that endovascular therapy is superior to best medical management alone in achieving more favourable outcomes (mRS, 0 - 3) at 90 days in subjects presenting with acute basilar artery stroke within 12 hours of the estimated time of onset.

The study enrolled 342 patients at 36 comprehensive stroke centers in China. All patients had occlusion of the basilar artery confirmed on vascular imaging within 12 hours of stroke onset, and they had severe symptoms at presentation, with an NIHSS score of at least 10. They were randomized in a 2:1 ratio to endovascular treatment or best medical management alone.

"It took us less than a year to enrol 342 patients," Nogueira noted. "To put this into perspective, it took the BASICS trial over 8 years to enrol 300 patients, so these are very high-volume centers."

He reported that two patients withdrew consent, and there were three patient crossovers on each side, comparing favorably with BASICS, leaving 226 patients in the intervention group and 114 in the control group.

Baseline characteristics were similar between the two groups; median age was 67 years, median NIHSS score was 24, about 25% received thrombolysis, and median time from stroke onset to randomization was 5 hours.

Results showed that the primary outcome — a favorable functional outcome (mRS, 0 - 3) at 90 days — was achieved in 22.8% of the control group and in 46% of the endovascular group, giving an adjusted risk ratio of 2.1 (P < .001).

The number needed to treat was just four.

"There were no surprises with secondary endpoints; everything was highly statistically significant," Nogueira said.

Specifically, there was a lower rate of overall disability in the shift analysis, with a common odds ratio of 2.8 favoring the intervention.  

Safety results showed an increased risk for symptomatic ICH in the endovascular group (5.3% vs 0.0%) but, despite that, 90-day mortality was significantly lower in the endovascular group (36.7% vs 55.3%).

Nogueira noted a limitation of the study was that it was conducted in China.

"This was a Chinese study and, as Asians are known to have higher rates of intracranial atherosclerotic disease, the overall degree of generalizability of our findings to Western countries needs to be considered," he commented.

However, subgroup analysis showed no treatment effect modification based on the presence of intracranial atherosclerotic disease, he noted.

Also, the proportion of comorbidities in the ATTENTION trial was similar to that in the BASICS trial, with the same degree of diabetes and atrial fibrillation.

Nogueira concluded that, in contrast to previous randomized trials of endovascular treatment for basilar artery occlusion, the ATTENTION trial was able to reinforce consecutive enrolment, resulting in a fast recruitment while minimizing crossovers. 

And he pointed out that the overall results are consistent with modern era observational studies, large registries, and meta-analysis.

Commenting on the study for theheart.org | Medscape Cardiology, Joanna Wardlaw, MD, professor of applied neuroimaging at the University of Edinburgh, United Kingdom, and chair of the ESOC Planning Group, said: "This is a very important result since it provides confirmation beyond doubt the benefit of thrombectomy versus medical therapy for basilar artery occlusion stroke up to 12 hours after onset."

Wardlaw added: "The trial was large enough to provide clear results and to enable subgroup analyses; no subgroup did not benefit from thrombectomy."

In a discussion after the presentation, Urs Fischer, MD, chair of the Department of Neurology at the University Hospital Basel, Switzerland, said he was not surprised by the results of the ATTENTION trial.

"We have been doing thrombectomy in patients with basilar artery occlusion now for 20 years, although trials are extremely important to answer these questions, so now we have some clear evidence," Fischer said. "Nevertheless, there are some caveats as this is an Asian population, but this is a proof of concept, and it is going in the right direction."

The ATTENTION trial was sponsored by the First Affiliated Hospital of University of Science and Technology of China.

European Stroke Organisation Conference (ESOC) 2022. Presented May 4, 2022.  


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