Effect of the Number of Neurointerventionalists on Off-Hour Endovascular Therapy for Acute Ischemic Stroke Within 12 Hours of Symptom Onset

Background: Off-hour presentation can affect treatment delay and clinical outcomes in endovascular therapy (EVT) for acute ischemic stroke. We aimed to examine the treatment delays and clinical outcomes of EVT between on- and off-hour admission and to evaluate the effect of hospital procedure volume and the number of neurointerventionalists on off-hour EVT. Methods and Results: From a multicenter registry, we identified patients who were treated with EVT within 12 hours of symptom. Annual hospital procedure volume was divided as low (<30), medium (30–60), and high (>60). The effect of the number of neurointerventionalists and annual hospital procedure volume on clinical outcome was estimated by the generalized estimation equation. Of the 31 133 stroke patients, 1564 patients met the eligibility criteria (mean age: 69±12 years; median baseline National Institutes of Health stroke scale score, 15 [interquartile range, 10–19]). Of 1564 patients, 893 (57.1%) arrived during off-hour. The off-hour patients had greater median door-to-puncture time (110 versus 95 minutes; P<0.001) compared with on-hour patients. Despite the treatment delay, the functional outcome at 3 months did not differ between off- and on-hour (odds ratio with 95% CI for 3-month modified Rankin Scale 0–2, 0.99 [0.78–1.25]; P=0.90). The presence of three neurointerventionalists was significantly associated with favorable outcomes at 3 months during on- and off-hour (2.07 [1.53–2.81]; P<0.001). The association was not observed for annual hospital procedural volume and the functional outcomes. Conclusions: The number of neurointerventionalists was more crucial to effective around-the-clock EVT for acute stroke patients than hospital procedural volume.