A bicentric study on the prevalence and clinical relevance of subarachnoid hyperdensities on flat-detector CT after thrombectomy in dominant, co-dominant, and non-dominant M2 occlusions.

BACKGROUND

Subarachnoid hyperdensities (SH) on flat-detector CT (FDCT) after mechanical thrombectomy (MT) are associated with less favorable clinical outcomes. We aimed to further elucidate the prevalence and clinical significance of SH following MT, especially in patients with dominant, co- and non-dominant M2 occlusions.

METHODS

728 patients from two comprehensive stroke centers were assessed for the presence of SH on FDCT. The primary outcome was the presence of SH on FDCT. The secondary outcome was modified Rankin Scale scores (mRS) at 90 days. Baseline procedural characteristics and clinical outcomes were analyzed using group comparisons and multivariable logistic regression. To remove the effect of confounding factors, a logistic regression model was built using inverse probability weighting.

RESULTS

In total, 411 patients were included. Prevalence of SH on FDCT was 171/411 (41.6 %), with particularly high prevalence in co- and non-dominant M2 occlusions (63%) and dominant M2 occlusions (53.9%). The occurrence of SH was independently associated with poor functional outcomes (adjusted OR for mRS at 90 days: 1.5; 95% CI, 1.1-2.2) and increased mortality (aOR: 1.7; 95% CI, 1.0-2.8). Increased risk of developing SH was particularly evident in patients with co- and non-dominant M2 occlusions (P < 0.001 OR = 3.78; 95% CI, 2.18-6.57) and dominant M2 occlusions (P < 0.001 OR = 3.07; 95% CI, 1.68-5.59) compared to large vessel occlusions. A higher number of device passes, specifically between 3 and 6 and more than 6, show an effect on the occurrence of SH P < 0.001 OR = 2.75; 95% CI, 1.56-4.84 and P = 0.02 OR = 3.45; 95% CI, 1.17-10.16 compared to fewer passes (1-3).

CONCLUSION

SH are common after MT, especially in M2 occlusions. They are associated with poorer functional outcomes in patients with co- and non-dominant M2 occlusions and higher numbers of device passes (>3).