Introduction: Multiple studies have correlated larger final infarct volume (FIV) with worse clinical outcomes. In INTERRSeCT, an international multicenter prospective cohort study, we sought to determine the favorable intracranial clot characteristics predicting smaller infarct volumes.
Methods: FIV was measured (24 ±12 hours after baseline imaging) in 605 patients from INTERRSeCT study by blinded readers using Quantomo (Cybertrial Inc, Calgary). Clot Burden Score (CBS) is a 10-point scale with 10 referring to a completely patent ipsilateral anterior circulation from ICA to both M2 arteries, whereas 0 refers to a completely occluded ipsilateral anterior circulation. Residual Flow Grade (RFG) assesses the radiological permeability of the clot to contrast, with grade 0, 1, and 2 defined as no contrast, diffuse ghosting, and hairline lumen, respectively. Both of these scores were assessed by a blinded reader to the FIV. Using ordinal logistic regression, FIV was divided into deciles as the outcome. CBS and RFG were analyzed from 0 to 10, and 0 to 2, respectively. Two models were used, the first has no recanalization status, while the second included it.
Results: The median FIVs with and without recanalization were 12.34 ml (IQR: 32.3 ml) and 22.15 ml (IQR: 60.12ml), respectively. CBS and RFG were independently predictive of FIV (p-value= <0.001 and 0.003, respectively). The common ORs for having one decile higher FIV for 1 point increase in CBS and RFG were 0.82 (CI: 0.77, 0.87) and 0.66 (CI: 0.51, 0.86), respectively. After adjusting for recanalization, the common ORs for having one decile higher FIV for 1 point increase in CBS and RFG were 0.83 (CI: 0.78, 0.88) and 0.72 (CI: 0.54, 0.94), respectively.
Conclusions: Residual flow grade and clot burden score are fast and practical techniques for practitioners treating acute ischemic stroke patients. Favorable RFG and CBS independently, predict lower infarct volumes regardless of whether recanalization achieved.