Impact of M2-segment occlusion angiographic shape on recanalization and clinical outcomes in mechanical thrombectomy.

BACKGROUND

Mechanical thrombectomy (MT) for M2-segment occlusions of the middle cerebral artery can be an effective treatment for acute ischemic stroke but its effectiveness and the choice of the first line strategy remains unanswered questions. The angiographic shape of the occlusion has been suggested to impact the recanalization rates in M1-segment occlusions. We aimed to investigate whether the angiographic shape of the M2-segment impacts the outcomes of MT with stent retriever (SR) or contact aspiration (CA).

METHODS

From January 2015 to December 2022, consecutive patients admitted to a single high-volume institution for acute ischemic stroke with an M2-segment occlusion treated by MT were included and retrospectively analyzed. Patients were classified into two groups, regular or irregular, according to the angiographic occlusion shape. Patients demographic, procedural, clinical and safety outcomes data were reviewed.

RESULTS

A total of 214 MT procedures were included and categorized as regular (39 %) and irregular (61 %) shape occlusion groups. Interrater agreement was high (k = 94 %). There were no significant differences between the two groups as regard demographic, procedural, clinical and safety outcomes except for smoking (33.5 % vs 16.8 %, p = 0.01). Procedural outcomes, recanalization rates and clinical outcomes did not significantly differ between the regular and irregular occlusion groups. In subgroup analysis, for irregular occlusions SR as a first-line strategy was associated with higher rates of excellent recanalization (mTICI 2c - 3) after the first pass compared to CA±SR (44 % vs 27.16 %, p = 0.05), and also better clinical outcomes, with lower 24-hour NIHSS (p < 0.01) and lower 3-month mRS (p = 0.04). In regular occlusions, no significant differences were found in recanalization rates or clinical outcomes when using SR or CA±SR.

CONCLUSION

Choosing SR as the first line strategy for irregular shape M2-segment occlusions is associated with higher rates of recanalization after the first pass and better clinical outcomes. Further prospective studies are needed to confirm our findings.