Introduction: Recent trial data demonstrating benefit of endovascular therapy (EVT) in acute ischemic stroke (AIS) patients has led to increased referrals to stroke centers for consideration of EVT. We aimed to characterize the baseline predictors and patterns of transfer for patients undergoing EVT.
Methods: We reviewed data of consecutive AIS patients who were transferred to our institution between 02-to-07/2015 within 6 hours of stroke onset for potential EVT. We compared baseline demographics, vascular risk factors (age, diabetes, hypertension, coronary or carotid disease, atrial fibrillation, anticoagulation use, prior history of stroke/TIA), NIHSS, ASPECTS, time from symptom onset to CT and to tPA infusion, transfer time and presence of large vessel occlusion between patients who underwent EVT versus those who did not upon transfer.
Results: Forty-three AIS patients were transferred to our institution within 6h of stroke onset and after treatment with IV tPA at outside hospitals for potential EVT; (age: 30-101, 42% women, 44% underwent EVT). In comparison to patients treated medically, those who underwent EVT had greater frequency of proximal arterial occlusion (95% vs. 38%, p<0.001) and higher baseline NIHSS scores (mean: 17 vs. 9, p<0.001). Although not statistically significant, the EVT group was younger (62 vs. 71 years) and had shorter transfer times (161 vs. 135 min). NIHSS (OR 1.2, 95% CI 1.0-1.5), but not proximal vessel occlusion (OR 6.5, 95% CI 0.5-81.9), independently predicted those who underwent EVT in a multivariable regression analysis. NIHSS was highly discriminatory for individuals undergoing EVT (area under the receiver operating characteristic curve: 0.9, p<0.001), with a NIHSS threshold of 9 having a negative predictive value of 100% and positive predictive value of 66%.
Conclusion: In this single center study; NIHSS was the only independent predictor of EVT in AIS transferred within 6 hours of symptom onset. A NIHSS threshold of less than 9 seemed to discriminate patients who did not ultimately undergo EVT at our institution. The limited work-up prior transfer and prolonged transfer time highlights the need for regional and national efforts to maximize the utility and benefit of EVT for AIS patients.