Effect of Cumulative Case Volume on Procedural and Clinical Outcomes in Endovascular Thrombectomy

Background and Purpose - The effect of endovascular thrombectomy (EVT) cumulative case volume (EVT-CCV) on outcomes of acute stroke patients has not been studied. This study investigated whether EVT-CCV was associated with outcomes. Methods - We identified all patients who underwent EVT for anterior circulation large vessel occlusion. Patients who met enrollment criteria were grouped into 5 based on the number of previous cases at each hospital. The number of cases that were recruited from each hospital and then assigned to each group (n) was designed to increase by the function of 10×2^(n-1); group 1 consisted of cases 1 to 10 at each hospital, group 2 was cases 11 to 30, group 3 was cases 31 to 70, group 4 was cases 71 to 150, and group 5 was cases ≥151. We tested whether EVT-CCV group was associated with procedural and clinical outcomes. Results - Nine hundred fifty-five patients fulfilled the enrollment criteria. Recanalization and good outcome positively correlated with EVT-CCV group (P<0.001 [correlation coefficient, r=0.122] for recanalization; P=0.002 [r=0.099] for good outcome), whereas symptomatic intracranial hemorrhage and mortality negatively correlated (P=0.039 [r=-0.067] for symptomatic intracranial hemorrhage; P=0.016 [r=-0.078] for mortality). EVT-CCV group was independently associated with recanalization (odds ratio, 1.182; 95% CI, 1.029-1.358) and good outcome (odds ratio, 1.187; 95% CI, 1.053-1.337). Conclusions - With increased EVT-CCV, recanalization and good outcome increased, whereas symptomatic intracranial hemorrhage and mortality decreased. Increased EVT-CCV was independently associated with recanalization and good outcome.