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Current Duplex Velocity-Based Estimates of Carotid Stenosis are Unreliable in Heart Failure Patients with Reduced Ejection Fractions
Saranya Sundaram, Tyler Buckley, Tru Dang, Eric Murphy, Mathew Wooster
Medical University of South Carolina, Charleston, SC

Introduction: Patients in heart failure demonstrate unique carotid duplex findings such as unusually low systolic velocities due to low cardiac output.The impact on estimations of carotid stenosis has only been described in severe impairment requiring ventricular assist devices(VADs).We studied the effect of abnormal ejection fraction(EF) without VAD dependence on current carotid consensus criteria. Methods: We performed a retrospective review of patients with diagnosed heart failure without VAD history who had computed tomography(CTA) or magnetic resonance angiography(MRA) available <6months of a standard carotid duplex ultrasound. Reduced ejection fraction was defined as EF<40% per NYHA classification. Statistics included chi square, independent t-test, parametric correlation, and linear regression analysis.Results: We identified 204 heart failure patients,72 with EF<40% and 132 with normal EF. Cohort demographics were generally similar with exception of age,history of coronary artery bypass graft(CABG),prior Impella or arterial balloon pump,and diuretic use(Table I).On analysis of the duplex velocities of both groups, we identified a significant decrease in the reported peak systolic velocities(PSV) in the internal carotid artery(ICA) and common carotid artery(CCA) with reduced EF(Table I).Parameteric correlation analysis supported a significant negative relationship between reduced ejection fraction and PSV in right ICA(p=.017)and CCA(p=.036) and ICA only on the left(p=.05);regression analysis suggested both clinical and statistical significance of EFs effect on right ICA/CCA PSV (Table II). ICA:CCA ratios and ipsilateral duplex findings in symptomatic patients were not significantly affected(Table II).On further investigation, a significant proportion of patients saw an increase in the category of their estimated stenosis from duplex to CT/MRA estimations on the left(p=.05).This difference, however, did not persist when only symptomatic patients were included with comparison of duplex velocities on the side relative to their symptoms(Table I).Conclusions: PSV may be an unreliable measure of carotid stenosis in low EF and possibly underestimate CT/MRI measurements.The differences could possibly be mitigated by exclusive use of ICA:CCA ratio or greater emphasis placed on patient symptoms to guide PSV reliability.


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