This study was a single-center, retrospective analysis of patients who were treated with SR or MAT as a first-line method for acute BAO from March 2016 to December 2019. The institutional review board approved this study (AJIRB-MED-MDB-20-084) and waived the requirement for written informed consent based on the retrospective study design.
All patients with a clinical diagnosis of acute ischemic stroke (AIS) due to basilar artery occlusion who underwent initiation of endovascular stroke treatment with complete angiographic evaluation were included. There was no predetermined protocol for the treatment of BAO with endovascular procedure at our hospital during the study period. The decision to initiate endovascular treatment in any given patient with BAO on presentation was left to the attending neurointerventional specialist’s discretion in agreement with the neurologist according to neurological guidelines.
All patients with BAO who arrived at our hospital underwent an initial imaging protocol including non-enhanced CT, CT angiography or MRI. During the study period, 52 patients who underwent endovascular treatment for acute BAO were initially enrolled. Among them, two patients with occlusion due to dissection were excluded. The remaining 50 patients were included in final analysis.
All procedures were performed by experienced neurointerventional radiologists and neurologists using a biplanar Allura Xper FD scanner (Philips Healthcare). Angiography was performed via the femoral approach using a 5-F angiographic catheter. An initial angiographic series from both vertebral arteries was obtained to confirm the location of the occlusion and to evaluate the best access to the occlusion site. Then, a 6-Fr shuttle catheter (Cook, Bloomington, IN, USA) was placed in the distal portion of the V2 segment of the dominant vertebral artery (VA) via a co-axial delivery method using an angiographic catheter and guidewire.
For SR thrombectomy, a microcatheter (Prowler Select Plus; Cordis Neurovascular, Miami Lages, FL, USA) with a 0.014 in. microguidewire (Traxcess; Microvention, Tustin, CA, USA) was passed through the occlusion site and placed distally. A retrievable stent (Solitaire; Covidine, Irvine, CA or Trevo; Stryker, Kalamazoo, MI) was introduced through the microcatheter and after full deployment was held in position for 3–5 min to engage the clot (Fig. 1a). All the stents we used were 4/20 mm in size and length. Subsequently, the microcatheter and stent were pulled back, with application of negative suction pressure through the Shuttle catheter, using a 50-mL syringe to minimize distal embolization.
For large bore suction catheter thrombectomy, a Penumbra 5MAX/ ACE 68 catheter (Penumbra, Alameda, CA) or Sofia 6F distal access catheter (MicroVention, Tustin, CA) with a microcatheter and a microwire was advanced coaxially to the proximal end of the thrombus to wedge the catheter next to the clot (Fig. 1c, d). After withdrawal of the microcatheter and microwire, we connected a 50-mL syringe to the proximal end of the reperfusion catheter for manual aspiration. The catheter was withdrawn slowly, maintaining a vacuum between the tip and the clot with application of negative suction pressure through the Shuttle catheter, also using the 50-mL syringe. If the vacuum released during catheter withdrawal, we placed a large bore suction catheter on the proximal BA or distal VA and performed angiography via that catheter to explore whether recanalization had been successful. In cases of persistent occlusion or incomplete recanalization, the microcatheter and microwire were reintroduced and the procedure repeated until maximal recanalization was achieved.
After the procedure, all patients were treated in the intensive care unit. A routine non-enhanced CT was performed immediately after all procedures to rule out intracranial hemorrhage. Contrast-enhanced CT scans were performed 24 to 48 h after the procedure. Then, general supportive care was initiated, including intravenous antiplatelet or anticoagulation therapy, cardiac monitoring, control of blood pressure, fever, blood glucose and all other essential variables following stroke guidelines.
Clinical data including sex, age, medical risk factors (hypertension, diabetes mellitus, hyperlipidemia, smoking, atrial fibrillation, coronary artery disease, previous stroke history), NIHSS score on admission and at discharge, intravenous tissue plasminogen activator (IV tPA) administration, modified Rankin Scale (mRS) score 3 months after treatment, hemorrhage and mortality were obtained for evaluation of clinical outcomes. Procedure time was defined as time from puncture to final recanalization in successful recanalization cases and time of last angiographic series in unsuccessful recanalization cases. Recanalization status was assessed on the final angiogram and was classified according to the modified thrombolysis in cerebral infarction (mTICI) scale; successful recanalization was defined as modified TICI 2b or 3. First pass effect (FPE) was defined as achieving complete recanalization (mTICI 3) with a single thrombectomy device pass . A favorable clinical outcome was defined as a three-month mRS score of 0–2. An intracerebral hemorrhage was classified according to the second European-Australasian Acute Stroke Study classification, and symptomatic ICH was defined as any CT-documented hemorrhage that was temporally related to deterioration in the patient’s clinical condition and a ≥ 4-point in NIHSS. All NIHSS and modified Rankin Score (mRS) grades were assessed by a consulting neurologist.
All analyses were conducted using SPSS for Windows (version 25.0; IBM, Armonk, NY, USA). Descriptive statistics of normally distributed data are reported as means and standard deviations; non-normally distributed data are summarized as medians and interquartile ranges (IQR). Differences between groups were examined using Fisher’s exact test or the Mann-Whitney test. Multivariable logistic regression analysis was performed to identify variables independently associated with a favorable clinical outcome. Statistical significance was defined as p ≤ 0.05.