“No significant difference” between aspiration and stent-retriever thrombectomy in medium vessel occlusions

Adam A Dmytriw

When utilised as a first-line technique for medium vessel occlusion (MeVO) stroke, aspiration and stent-retriever thrombectomy have demonstrated “no significant difference” in imaging-related or clinical outcomes. That is according to a multicentre, propensity score-matched analysis including more than 400 patients, the results of which have been published in the journal Stroke: Vascular and Interventional Neurology.

“Altogether, these findings do not suggest one technique […] to be associated with any greater probability of technical success, safety, or better long‐term functional outcomes,” write authors Adam A Dmytriw (Massachusetts General Hospital, Boston, USA) et al. “The technical success rates with either technique were high (80–90%) and are consistent with those reported from secondary analyses of clinical trials.”

Led by first author James Siegler (Cooper Neurological Institute, Camden, USA), the researchers initially note that, due to the lack of data regarding MeVO thrombectomy, they set about evaluating outcomes according to first‐line techniques in a large, multicentre registry referred to as ‘MAD-MT’. This consortium was founded by Dmytriw and Adrien Guenego (Erasme University Hospital, Brussels, Belgium). Imaging, procedural and clinical outcomes were assessed, with acute proximal or distal MeVO patients being treated at 37 sites across 10 countries and analysed according to the first‐line thrombectomy technique they received—aspiration or stent retriever.

Multivariable logistic regression and propensity‐score matching were used to estimate the odds of the primary outcome—expanded thrombolysis in cerebral infarction (eTICI) scores of 2b–3, defined as ‘successful recanalisation’—between the two treatment groups. Secondary outcomes included the ‘first‐pass effect’, eTICI scores of 2c–3, intracerebral haemorrhage, 90‐day modified Rankin scale (mRS) scores, and 90‐day mortality.

Of 440 included patients, 55.5% were treated with aspiration thrombectomy versus 44.5% with a stent retriever. Dmytriw et al report those treated via stent-retriever thrombectomy as having lower baseline Alberta stroke programme early computed tomography scale (ASPECTS) scores (median=8 vs 9); higher National Institutes of Health stroke scale (NIHSS) scores (median=13 vs 11); and non-significantly fewer medium‐distal occlusions (M3, A2, P2 or other; 17.4% vs 23.8%).

Use of a stent retriever was associated with a 15% reduction in the likelihood of successful recanalisation (odds ratio [OR]=0.85)—but this difference was not found to be significant after multivariable adjustments across the total cohort (adjusted OR=0.88), or in the propensity score-matched cohort, in which both groups included a total of 105 patients (adjusted OR=0.94). Furthermore, there was no significant association between thrombectomy technique and secondary outcomes in the propensity score-matched, adjusted models, the authors relay.

As such, they conclude that—in this large, heterogenous, multinational cohort of MeVO patients—no significant differences in imaging-related or clinical outcomes were observed between aspiration and stent-retriever thrombectomy. Dmytriw et al go on to assert that there appears to be “no significant technical or functional advantage” to using either specific technique.

However, despite this cohort being “one of the largest to date” to report outcomes associated with first-line aspiration versus stent-retriever thrombectomy in MeVO/distal vessel occlusions, they acknowledge the non-randomised allocation of the techniques; the influence of unmeasured confounding factors; and some missing reperfusion data as well as between-site variations, as limitations of the analysis.

“Other clinical and imaging predictors, such as clot composition or hyperdense vessel sign, warrant further exploration to better understand the selective vulnerability of certain occlusions to one device or another,” they add, also noting that multiple ongoing randomised trials are “anticipated to shed light on these treatment considerations”.


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