Isolated middle cerebral artery significantly increases risk of postoperative stroke after transcarotid revascularization in asymptomatic patients.

Objective: Limited research has been conducted to demonstrate the safety and efficacy of flow reversal in transcarotid revascularization (TCAR) patients with an ipsilateral isolated middle cerebral artery (iMCA). We hypothesize that an iMCA decreases tolerance to flow reversal and increases the risk of ipsilateral ischemic stroke after TCAR.

Methods: Clinical data and outcomes for TCAR were collected prospectively through our multihospital single-institution Vascular Quality Initiative study between January 2019 and April 2024. Patient characteristics, imaging, and outcomes were reviewed retrospectively. Symptomatic patients and patients with inadequate intracranial imaging for appropriate circle of Willis (CoW) assessment were excluded. All anatomical segments of the CoW were evaluated by the same research assistant and radiologist and classified as normal, hypoplastic, or absent. The anterior semicircle and both the ipsilateral and contralateral posterior semicircles were further classified as complete, incomplete, and hypoplastic accordingly. The ipsilateral MCA was defined as isolated (iMCA) if there were incomplete segments in both the anterior semicircle and the ipsilateral posterior semicircle. Patients were then divided into iMCA and non-iMCA groups for comparison. Primary outcome was immediate neurological event (INE), defined as any transient ischemic attack or stroke diagnosed within 24 hours of the intervention.

Results: A total of 230 TCARs (218 patients) performed for asymptomatic severe carotid artery stenosis were included in our analysis. Baseline characteristics did not differ significantly between groups. The median treated lesion length was significantly longer in the nonisolated MCA group at 24 mm compared with 19 mm. After imaging analysis, no patient was found to have a complete CoW. An ipsilateral iMCA was found in 27 cases (11.7% of 230 cases, 12.4% of 218 patients). A total of four patients (1.7%) suffered an INE. Cases complicated by INE had significantly longer flow reversal times (13.5 minutes vs 9 minutes; P = .0142), but did not differ between the iMCA and non-iMCA groups. INE occurred in three cases (11.1%) in the iMCA group vs one (0.5%) in the non-iMCA group (P = .005). iMCA was significantly associated with risk of INE on univariable logistic regression (odds ratio, 25.3; 95% confidence interval, 2.5-252.4; P = .006).

Conclusions: In this retrospective, single-center study of 230 patients with asymptomatic carotid artery stenosis undergoing TCAR, an iMCA significantly increases the risk of postoperative stroke. Our results suggest that comprehensive intracranial imaging should be considered for all patients to assess the CoW anatomy optimally before flow reversal. We recommend avoiding flow reversal in this patient population and considering alternative treatment methods such as carotid endarterectomy with shunting or transfemoral carotid artery stenting.