High mechanical thrombectomy procedural volume is not a reliable predictor of improved thrombectomy outcomes in patients with acute ischemic stroke in the United States.

Background: The volume of mechanical thrombectomy (MT) performed at hospitals is used as one of the criteria for advanced-level designation for stroke care.

Objective: Our study sought to determine the relationship between annual MT procedural volume and in-hospital outcomes in acute ischemic stroke patients undergoing MT in the United States.

Methods: We analyzed the National Inpatient Sample from 2016 to 2020. The hospitals were grouped into quartiles based on the volume of MT procedures performed within the calendar year. We compared the rates of routine discharge/home health care; in-hospital mortality, and post-treatment intracranial hemorrhage (ICH) between the quartiles after adjusting for potential confounders.

Results: Patients undergoing MT ranged from 15,395 in quartile 1 to 78,510 MT in quartile 4. There were lower rates of discharge home/self-care of 22.5%, 20.8%, and 20.8% for quartiles 2, 3, and 4, respectively, compared with 34.9% in quartile 1. The odds of ICH increased to 1.81 (p < 0.001), 1.84 (p < 0.001), and 1.98 (p < 0.001) among the quartiles from lowest to highest procedural volumes. The odds of home discharge/self-care decreased to 0.66 (p < 0.001), 0.60 (p < 0.001), and 0.63 (p < 0.001) among the quartiles from lowest to highest procedural volumes. The odds of in-hospital mortality increased to 1.92 (p < 0.001), 1.99 (p < 0.001), and 1.84 (p < 0.001) among the quartiles from lowest to highest procedural volumes.

Conclusions: We observed a paradoxical relationship between adverse outcomes and the annual procedural volume of MT at the hospital presumably due to the higher severity of acute ischemic stroke treated at high-volume hospitals.