Introduction: Mechanical thrombectomy (MT) for the treatment of acute ischemic stroke has been growing in popularity. Data regarding the therapeutic benefit of MT has been called into question leading to increased scrutiny of its utilization. Our objective was to determine if the rate of mortality following MT has decreased over time and to quantify the independent effect of high-volume stroke centers (annual stroke volume >= 67th percentile) and high-volume MT centers (annual MT volume >= 10 cases) on mortality.
Methods: We analyzed the Nationwide Inpatient Sample from 2006 to 2011 for patients with a primary diagnosis of acute ischemic stroke that received treatment with MT. Temporal trends in mortality were examined using Spearman's rank correlation. Multivariate analysis of mortality was performed with binary logistic regression using backward stepwise selection with probability for entry at 0.05 and removal at 0.10.
Results: Hospitals performing MT comprised less than 6% of all hospitals treating ischemic stroke. The percentage of stroke cases treated with MT rose from 0.05% of cases in 2006 to 0.79% in 2011. In-hospital mortality decreased over the study period from 27.3% in 2006 to 18.3% in 2011 (Spearman's rank correlation coefficient of -.047, P<.001). Multivariate analysis found high-volume stroke centers and high-volume MT centers to independently reduce the odds of mortality (OR=0.343, P<.001; OR=0.791, P<.001, respectively).
Conclusions: The utilization of MT represents a small percentage of stroke cases nationwide, although the trend is increasing. Both a high-volume stroke center and high-volume MT center are independently associated with decreased mortality. Additionally, mortality following MT appears to be decreasing over time. This may be a result of a learning curve, improved patient selection, and/or device improvements. Randomized clinical trials remain essential to evaluate the potential benefit of endovascular devices and identify patients that will benefit the most from intervention.
Patient Care: Our study on mechanical thrombectomy is the largest to date and is the first to simultaneously analyze the impact of high-volume stroke centers, high-volume mechanical thrombectomy centers, and temporal-trends. Research to continually assess the therapeutic benefit of interventions that are lacking evidence from randomized clinical trials is important for patient care.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe trends in mechanical thrombectomy utilization, 2) Explain mortality trends in this patient population, 3) Discuss the factors that influence mortality including high-volume stroke centers and high-volume mechanical thrombectomy centers.