The Source for Neurovascular News and Education

November 29, 2022

The findings may have implications for development of regional care systems for acute stroke, researchers say.



Hospitals that accrue higher case volumes for endovascular thrombectomy over time tend to have higher rates of successful recanalization and good outcomes among patients with acute ischemic stroke, according to an analysis recently published online in Stroke.


“Previous studies suggested that a larger volume of acute stroke patients at a hospital was associated with lower mortality,” write the authors, led by Byung Moon Kim, MD (Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea). “Those studies involved all acute stroke patients and have not focused on patients who received endovascular treatment.”


Prior to the endovascular thrombectomy era, increased hospital endovascular treatment volume for acute stroke was not linked with mortality outcomes in a large retrospective study. Given the recent advent of contact aspiration and stent retriever thrombectomy, the researchers say, it is important to determine whether volume effects on outcome are now apparent.


Kim et al categorized 955 patients who underwent endovascular therapy for anterior circulation large-vessel occlusion into one of five groups based on the number of previous cases at each hospital. The investigators then tested whether cumulative case volume group was associated with procedural and clinical outcomes.


Recanalization and good outcome, defined as 90-day mRS 0-2, were positively correlated with cumulative case volume, while symptomatic intracranial hemorrhage (ICH) and mortality were negatively correlated, as were door-to-puncture, and puncture-to-recanalization times. Onset-to-recanalization time, however, showed no significant correlation.


Outcomes Associated With Cumulative Case Volume


Correlation Coefficient

P Value



< 0.001

90-Day mRS 0-2



Symptomatic ICH







Multivariate analysis confirmed that endovascular cumulative case volume was independently associated with recanalization (OR 1.182; 95% CI 1.029-1.358) and good outcome (OR 1.187; 95% CI 1.053-1.337).


According to Kim and colleagues, the study suggests that workflow of endovascular therapy for acute stroke at each hospital improved with increasing case volume, which might partly contribute to better outcomes. However, they stress that the results are not meant to imply that cumulative case volume of each operator or hospital “is more important in outcomes than the other factors, including patient factors.”

Kim et al conclude that the impact of cumulative case volume on outcomes is something that “should be considered in the setting of regional system of care for acute stroke.”


Questions remain as to how to provide an increasing number of patients with acute stroke with experienced endovascular care, they note. They suggest that a threshold of 12 endovascular thrombectomies, which is indicated by the Joint Committee as that needed for operator proficiency, may be too low.



Kim BM, Baek JH, Heo JH, et al. Effect of cumulative case volume on procedural and clinical outcomes in endovascular thrombectomy. Stroke. 2019;Epub ahead of print.



Kim reports consulting for Stryker Pacific Ltd.