Outcomes After Thrombectomy for Primary and Secondary Medium Vessel MCA Occlusions: a Nationwide Registry Study.

Abstract

Background: Medium vessel occlusions (MeVO) can be either isolated events (primary), or secondary to thrombus migration from a large vessel occlusion to a medium-sized vessel. Outcomes following endovascular thrombectomy (EVT) in the middle cerebral artery (MCA) may differ between primary and secondary MeVOs. This study aimed to assess the association between primary/secondary MeVOs and clinical outcomes following EVT in a nationwide patient cohort.

Method: Patients undergoing EVT were included in two Swedish quality registries. Secondary MeVO was defined as distal migration of a solitary thrombus between baseline CT-angiography and EVT, or basal ganglia infarction on postoperative CT in a patient that presented with a single MeVO on baseline CT-angiography. The primary outcome was good 90-day functional outcome (modified Rankin Scale 0-2). Postoperative change in the National Institutes of Health Stroke Scale-score (NIHSS), was a secondary outcome. Successfully revascularized patients (mTICI 2b-3) were compared with non-revascularized patients in exploratory analyzes.

Results: Of the 5662 EVTs performed in Sweden (2018-2022), 1118 (20%) targeted solitary MCA territory MeVOs, with 819 (73%) being primary and 299 (27%) secondary. Functional outcomes did not differ between the primary and secondary MeVO groups (OR 0.86, CI 95% 0.65-1.14). Likewise, there was no significant difference in postoperative NIHSS scores (0.26, CI 95% -0.71 to 1.24), between groups (p = 0.597). Successful revascularization was associated with increased chance of good functional outcome for both primary (OR 3.77, CI95% 2.28-6.24, p < 0.001) and secondary MeVOs (OR 2.49, CI95% 1.21-5.14, p = 0.013).

Conclusions: Patients with a single primary or secondary MCA MeVOs have similar EVT outcomes and both groups seem to benefit from recanalization in exploratory analyses. This indicates that that EVT should not be withheld based on primary/secondary MeVO status.