What question did this study set out to answer?

To compare the effectiveness and safety of mechanical thrombectomy in patients with acute primary embolic M2 occlusions treated within late and early windows.

March 31, 2026Open Access

Outcomes of mechanical thrombectomy in acute stroke due to primary embolic middle cerebral artery M2 occlusions: a comparison of late versus early windows

Key Points

To compare the effectiveness and safety of mechanical thrombectomy in patients with acute primary embolic M2 occlusions treated within late and early windows.
Retrospective analysis of patients treated with MT from the ARTISTA registry (2017–2024)
Comparison of outcomes for late (>6 h) and early (≤6 h) treatment windows
Outcomes assessed included good outcome, futile recanalization, successful recanalization, and symptomatic intracranial hemorrhage
Utilized multivariable logistic regression and inverse probability of treatment weighting (IPTW) for analysis.
Among 524 patients, 207 (39.5%) received MT in the late window
Good outcome rates were numerically lower in late treatment (58.9%) compared to early (64.4%)
Rates of futile recanalization were higher in late treatment (37.8% vs 32.5% for early)
Successful recanalization rates were nearly identical (95.7% late vs 95.6% early)
No significant differences were found in outcomes between late and early windows.

Abstract

Background: Current guidelines consider mechanical thrombectomy (MT) reasonable for M2 segment middle cerebral artery (MCA) occlusions within 6 h of symptom onset, yet the impact of delayed intervention in this population remains unclear. Objectives: This study compared effectiveness and safety outcomes of MT performed in late (>6 h) versus early (⩽6 h) treatment windows in patients with acute primary embolic M2 occlusions. Design: We retrospectively analyzed patients with primary embolic M2 occlusions treated with MT within 24 h of onset from the ARTISTA (A Registry for Thrombectomy In Stroke Therapy from Andalusia) registry (2017–2024) in Seville-Huelva, Spain. Methods: Outcomes compared between late and early treatment groups included good outcome (90-day modified Rankin Scale (mRS) 0–2 or return to prestroke mRS), futile recanalization (FR; 90-day mRS >2 despite successful recanalization), successful recanalization (modified Thrombolysis in Cerebral Infarction ⩾2b), and symptomatic intracranial hemorrhage (sICH). Multivariable logistic regression and inverse probability of treatment weighting (IPTW) analyses were performed to evaluate associations between treatment window and MT outcomes. Results: Among 524 patients (median age 76, 48.3% women), 207 (39.5%) underwent MT in the late window. Late treatment showed numerically lower rates of good outcome (58.9% vs 64.4%) and higher rates of FR (37.8% vs 32.5%) and sICH (3.4% vs 3.2%), though none were statistically significant (all p ⩾0.211). Successful recanalization rates were nearly identical between the late and early windows (95.7% vs 95.6%; p = 0.970). IPTW-adjusted analyses also found no significant differences in good outcome (adjusted odds ratio (aOR), 0.82; 95% confidence interval (CI), 0.39–1.73; p = 0.600) or FR (aOR, 1.19; 95% CI, 0.56–2.50; p = 0.653) at 90 days. Conclusion: In this multicenter real-world cohort, MT performed beyond 6 h showed effectiveness and safety outcomes comparable to early-window intervention in patients with primary embolic MCA M2 occlusions.

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