Patient selection for mechanical thrombectomy.

PURPOSE: To evaluate the influence of tissue parameters as assessed by multimodal computed tomography and procedural parameters on clinical outcome after mechanical thrombectomy.
METHODS: A total of 301 consecutive patients with acute onset ischemic stroke were included in this study. Of these, 65 had thromboembolic occlusions of the carotid T or middle cerebral artery (MCA) and underwent mechanical thrombectomy. Tissue parameters were given by unenhanced CT and perfusion CT (PCT) parameter maps of total hypoperfused tissue, infarct core, and tissue at risk. Procedural parameters comprised time from symptom onset (SO) to PCT, from SO to the first angiographic series, and from SO to vessel recanalization (occlusion time). In a subset of 22 fully recanalized occlusions, infarcted tissue and "tissue at risk" as defined by PCT were coregistered to final infarcts on follow-up imaging.
RESULTS: Thrombolysis in cerebral infarction score (TICI) 2b/3 recanalization was achieved in 58/65 patients (89%). Only the infarct core size (p = 0.007) and the ratio of the infarct core relative to the tissue at risk (p = 0.001) yielded significant differences regarding the clinical outcome. Small infarct cores and low ratios of core size relative to the tissue at risk were correlated with a favorable outcome after mechanical thrombectomy. In the PCT coregistration subset, the congruency between predicted infarct cores and final infarcts was 68%, and between tissue at risk and final infarcts 7%, respectively.
CONCLUSIONS: The size of the infarct core and the ratio relative to the tissue at risk are more relevant parameters for clinical outcome after mechanical thrombectomy than time related factors.