Effect of collateral level in CT angiography on clinical prognosis in stroke patients treated with mechanical thrombectomy after six hours

Objectives: Collaterals have an effect on the protection of penumbra tissue. We evaluated the effect of collaterals on single-phase computed tomography angiography (CTA) in patients with AIS treated with MT after 6 hours.
Methods: We evaluated patients with ICA or M1 segment of MCA occlusion, time of symptom-groin puncture >6 hours, having CTA before MT, modified Treatment In Cerebral Ischemia score (mTICI) 2b-3 recanalization after MT. Data of collateral levels, outcome measures, timings and other variables were collected from Turkish Interventional Neurology Database. The level of collaterals was assessed with modified Tan scale.
Results: A total of 57 patients were included in our study. The median age was 64[56.5-75] years. The median NIHSS score at onset was 15[12-17.5] points. A total of 33 (57.9%) patients had good collaterals on CTA. Hypertension (HT) and diabetes mellitus (DM) rates were increased in the poor collaterals group. NIHSS scores decreased at the 24th hour in both good and poor collaterals groups. Twenty-two (66.7%) patients in the good collaterals group and 11 (45.8%) patients in the poor collaterals group had good clinical outcomes. However, there was not a significant difference (p=0.174, OR: 2.364; 95% CI: 0.802-6.697). Mortality rates were different in both groups, but the difference was not found to be significant (5[15.2%] versus 8[33.3%], p=0.124, OR:0.357; 95% CI: 0.1-1.278).
Conclusion: Good collaterals on single-phase CTA was not associated with improved neurological outcomes in AIS patients treated after 6 hours.