Abstract TP188: Doppler Velocity Ratio Parameter Adjunct to Conventional Risk Scores May Enhance the Predictability of Ischemic Stroke in Asymptomatic Carotid Stenosis

Abstract

Introduction: The prediction of ischemic stroke in patients with asymptomatic carotid stenosis (ACS) is important in clinical practice. Conventional cardiovascular risk scores may be used for these purpose, although not validated. We also incorporate carotid doppler ultrasonography (CDU) parameters to validate whether they may enhance the predictive power of conventional risk scores for ischemic stroke in ACS. Hypothesis: Conventional risk score combined with CDU parameters may predict the risk of ischemic stroke in ACS. Methods: From January 2010 to December 2017, we were retrospectively enrolled consecutive asymptomatic patients with more than 50% carotid stenosis by CDU criteria. Medical records of all participants were reviewed to assess conventional risk scores (Framingham stroke risk score (FSRS) and ASCVD risk score) and to confirm the occurrence of ischemic stroke events for up to 10 years. The peak-systolic-velocity (PSV), peak-systolic-velocity-ratio and peak-systolic-and-end-diastolic-velocity-ratio (PSV/EDV, PER) between internal and common carotid artery were evaluated. Univariate Cox proportional hazard regression, time-dependent Cox regression, and net reclassification index (NRI) were used to assess the predictability of explanatory variables and models. Results: A total of 150 patients (mean age 71.5 years, 111 males) were enrolled. During the follow-up period (mean 4 years), twelve ischemic stroke events were observed. In ROC curves for prediction of ischemic stroke in ACS, the AUC of the FSRS and ASCVD was 0.606 (CI 0.449-0.762) and 0.576 (CI 0.448-0.708). Among all CDU parameters, only higher PER was significantly associated with increasing risk of ischemic stroke (HR 1.764, CI 1.089-2.439, p=0.034). The addition of PER improved the predictive power; AUC of the FRSR and ASCVD risk score combined with PER was 0.649 (CI 0.506-0.792, p<0.001) and 0.621 (CI 0.499-0.742, p=0.007), respectively. NRI of PER combined FRSR was +10.7% (p=0.014) and +8.2% (p=0.042) for PER combined ASCVD risk score. Conclusion: The predictability of conventional risk scores has predictive power to ischemic stroke in ACS, although not substantial. This predictive power may be enhanced by doppler velocity ratio parameter, especially PER.