BARCELONA, Spain — In stroke due to basilar artery occlusion, the best technique to use for thrombectomy appears to depend on the underlying etiology of the clot, a new trial suggested.

The Chinese ANGEL-COAST randomized trial compared two different techniques used for endovascular thrombectomy — either contact aspiration or stent retriever — in patients with basilar artery occlusion stroke.

Results showed that using contact aspiration on the first attempt at clot removal achieved higher initial reperfusion rates without increasing the risk for symptomatic intracerebral hemorrhage or periprocedural complications.

However, this advantage was offset by lower rates of final recanalization and similar procedural duration, resulting in no significant difference in 90-day functional outcomes between the two groups.

Subgroup analyses also suggested that contact aspiration may be more suitable for patients with embolic type clots while the stent retriever may be preferable for occlusions caused by intracranial atherosclerosis.

“Our results do not give a definite answer,” trial investigator Raul Nogueira, MD, professor of neurology and neurosurgery at University of Pittsburgh School of Medicine, Pittsburgh, told Medscape Medical News.

“A reasonable conclusion would be that for basilar artery occlusion stroke use of contact aspiration for the first pass, and then to switch to a stent retriever for subsequent attempts at removing the clot, may be the best approach,” he suggested.

Nogueira added that he favors contact aspiration for embolic occlusions in the basilar artery but believes patients with occlusions that stem from intracranial atherosclerotic disease are likely to do better with a stent retriever.

The trial results were presented at 17th World Stroke Congress (WSC) 2025.

Which Technique Is the Best?

Contact aspiration and stent retriever are two different techniques used in endovascular treatment of stroke for clot removal.

Contact aspiration involves bringing a catheter into contact with the clot and then using a syringe to aspirate the clot. Whereas with a stent retriever, a stent is introduced with a wire, and the clot is incorporated into the stent mesh and removed.

Operators may have a personal preference as to which technique they use, but it would be preferable for that decision to be determined by individual patient characteristics, Nogueira said.

He noted that while the two techniques have shown similar effectiveness for clot removal in the anterior circulation, data from large observational registries in Western populations suggest that, specifically for basilar artery occlusions in the posterior circulation (PC), contact aspiration may be superior to the stent retriever.

The ANGEL-COAST trial was conducted to investigate this further.

The trial included 340 Chinese patients with stroke caused by basilar artery occlusion who were within 24 hours of stroke onset and had evidence of salvageable tissue (PC Alberta Stroke Program Early CT Score > 6).

Patients were randomly assigned to endovascular treatment with either the contact aspiration or stent retriever approach. Operators were required to make at least three revascularization attempts using the assigned thrombectomy technique before switching to another method as rescue therapy.

The aspiration catheter used was manufactured by DEEPIN Technology, Beijing, China, but the size of the aspiration catheter was at the operators’ discretion as was stent retriever selection.

The primary outcome was the first pass effect, defined as near-complete recanalization (eTICI 2c/3) after first thrombectomy pass without any rescue treatment. This showed a significant benefit with the contact aspiration approach.

The intention to treat analysis showed near complete reperfusion after the first pass in 43.5% of the contact aspiration group vs 27.4% of the stent retriever group, giving a treatment effect odds ratio (OR) of 2.04 (95% CI, 1.30-3.22; P = .002.)

Large Randomized Controlled Trials Needed

The per protocol analysis, which included 311 patients, showed an even larger effect, with reperfusion rates at first pass of 49.7% vs 27.2%, giving an OR of 2.65 (95% CI, 1.65-4.24; P < .001).

However, reperfusion rates showed an opposite effect, with near complete reperfusion achieved in 87.6% of the aspiration groups vs 94.0% of the stent retriever group, giving a treatment effect OR of 0.45 (95% CI, 0.21-0.99; P = .046).

Nogueira noted that subgroup analysis showed patients who have underlying intracranial atherosclerotic disease may benefit less from contact aspiration than those who had a stroke caused by an embolic occlusion.

He explained that among patients without intracranial atherosclerotic disease, outcomes with contact aspiration appeared markedly better than with stent retrievers. However, because the trial was conducted in a Chinese population — where intracranial atherosclerosis is more common — this may account for the lack of an overall benefit with contact aspiration in the final reperfusion results.

“In this trial we had a mixed population, and we didn’t see a clear result. I think in future we need to separate these two categories of patients and see if we can prove this hypothesis,” he added.

Nogueira pointed out that the fact that this was a Chinese trial may limit the generalizability of the study findings.

“Chinese patients have high rates of intracranial atherosclerosis in basilar artery occlusion stroke which may limit the ability to generalize these findings to other ethnicities. Further large, randomized trials are needed to validate the results of the ANGEL-COAST trial in Western populations,” he concluded.

Commenting on the trial results for Medscape Medical News, Amrou Sarraj, MD, professor of neurology at Case Western Reserve University School of Medicine, Cleveland, suggested that the results pointed to trying contact aspiration first for basilar artery occlusion.

“These results give the operator multiple possibilities to open the vessel. For basilar artery occlusion it seems worthwhile trying the faster technique of contact aspiration first,” he said.

ANGEL-COAST trial was funded by the grants from the Noncommunicable Chronic Diseases-National Science and Technology Major, National Key R&D Program of China, Beijing Natural Science Foundation, National Natural Science Foundation of China, and Beijing Hospitals Authority’s Ascent Plan. Nogueira reported no relevant disclosures.