Long-term follow-up results of nonemergent EC-IC bypass surgery for symptomatic, hemodynamically compromised chronic large- vessel occlusion or stenosis: quantitative radiologic analysis and clinical outcomes

Objective: This study aimed to demonstrate the effectiveness of nonemergent extracranial-to-intracranial bypass (EIB) in symptomatic chronic large artery atherosclerotic stenosis or occlusive disease (LAA) through quantitative analysis of computed tomography perfusion (CTP) parameters using RAPID software. Methods: : We retrospectively analyzed 86 patients who underwent nonemergent EIB due to symptomatic chronic LAA. CTP data obtained preoperatively, immediately postoperatively (PostOp0), and 6 months postoperatively (PostOp6M) after EIB were quantitatively analyzed through RAPID software, and their association with intraoperative bypass flow was assessed. The clinical outcomes, including neurologic state, incidence of recurrent infarction and complications, were also analyzed. Results: : The time-to-maximum (Tmax) >8 s, >6 s and >4 s volumes decreased significantly at PostOp0 and up through PostOp6M (preoperative, 5, 51, and 223 ml (median), respectively; PostOp0, 0, 20.25, and 143 ml, respectively; PostOp6M, 0, 7.5, and 148.5 ml, respectively; p<0.001, p<0.001, and p6 s and >4 s volumes was significantly correlated with the bypass flow at PostOp0 and PostOp6M (PostOp0, r=0.367 (p=0.001) and r=0.275 (p=0.015), respectively; PostOp6M r=0.511 (p<0.001) and r=0.391 (p=0.001), respectively). The incidence of recurrent cerebral infarction was 4.7%, and there were no major complications that produced permanent neurological impairment. Conclusion: Nonemergent EIB under strict operation indications can be a feasible treatment for symptomatic, hemodynamically compromised LAA patients.