Severity-Dependent Patterns of Hemodynamic Change in Symptomatic Carotid Stenosis during the Waiting Period Before Endarterectomy

Objective To determine whether the rate of hemodynamic change after a symptomatic carotid event differs between moderate and severe stenosis. Methods Serial duplex examinations in symptomatic patients awaiting carotid endarterectomy were analyzed with a linear mixed-effects model, using an extended, prospectively maintained database. Maximum internal carotid artery peak systolic velocity (ICA PSV) was modeled as a linear function of time from the index event interacting with baseline severity (moderate 125-229, severe ≥230 cm/s), with a random intercept per patient. The rate of change (cm/s per day) and the moderate-severe difference were the principal outcomes. Categorical interval comparisons and paired within-patient changes, including distal common carotid artery (CCA) PSV, were secondary analyses. Results The time course of maximum ICA PSV differed by baseline severity (interaction p = .006). The modeled rate of change was +1.20 cm/s per day (95% CI 0.28 to 2.12) in moderate and -0.21 cm/s per day (95% CI -0.58 to 0.17) in severe stenosis (difference 1.41 cm/s per day, 95% CI 0.42 to 2.40; p = .005). Secondary analyses were consistent: moderate stenosis accelerated with stable inflow, whereas severe stenosis showed no further ICA acceleration but a fall in distal CCA PSV (-3.0 cm/s; p < .001). Conclusion The rate of hemodynamic change during the waiting period depends on baseline severity: moderate stenosis accelerates, whereas severe stenosis shows little further ICA acceleration, consistent with behavior near a velocity ceiling. Maximum ICA PSV and distal CCA PSV are best read as separate, time-sensitive variables rather than as a single ratio.