Impact of Flow Reversal Duration on Neurological Outcomes of Transcarotid Artery Revascularization (TCAR)

Abstract

Flow reversal is a key component of transcarotid artery revascularization (TCAR). However, the impact of flow reversal duration on neurological outcomes and the duration of flow reversal which optimizes TCAR's outcomes is not known. We evaluated the association of flow reversal time with the intraoperative and postoperative neurological outcomes of TCAR. We studied all patients undergoing TCAR from September 2016 to October 2021. The exposure of interest was the duration of flow reversal. Multivariable logistic and fractional polynomial models were used to study the impact of flow reversal duration on in-hospital stroke, intraoperative neurological change/intolerance and stroke/death following TCAR and to identify the flow reversal time above which significant perioperative neurological events occur. The study included 19,462 patients with mean age of 73.4years who were mostly Caucasian (91%) and male (63%). The mean flow reversal time was 10.7minutes, and the overall stroke rate was 1.4%. The odds of intraoperative neurological change increased by 3.6% per minute increase in flow reversal time (odds ratio (OR), 1.04; 95%, 1.01-1.06; P<0.002). Flow reversal duration >10minutes was associated with 78% increased odds of neurological changes compared to flow reversal duration <10minutes. There was no significant association between flow reversal duration and stroke, and stroke/death in the first 5minutes after initiation of flow reversal. The odds of stroke increased by 2.7% per minute increase in flow reversal time >5minutes (OR, 1.03; 95%, 1.01-1.04; P<0.001), with flow reversal duration >10minutes associated with 38% increased odds of stroke compared to flow reversal duration ≤10minutes (OR, 1.37, 95% confidence interval (CI), 1.09-1.73, P=0.006). The odds of stroke/death increased by 2.5% per minute increase in flow reversal time >5minutes (OR, 1.03; 95%, 1.01-1.04; P<0.001). Flow reversal duration >10minutes was associated with 25% increased odds of stroke/death compared to flow reversal duration <10minutes (OR, 1.25, 95% CI, 1.01-1.53, P=0.038). Symptomatic status did not modify outcomes. Our findings suggest that outcomes following TCAR are optimal if the duration of flow reversal is minimized. A clinical cutoff time of 10minutes is suggested by this study and recommended as a guide. Further studies targeted at the flow reversal component of TCAR are needed to solidify the evidence regarding the clinical effects of temporarily induced retrograde cerebral blood flow during TCAR.