Carotid Duplex Ultrasonography to Assess Severity of Low-Flow Low-Gradient Aortic Stenosis

Patients with low-flow, low-gradient aortic valve stenosis constitute a substantial subset of all severe aortic stenosis patients. However, assessment of true severity of these patients can be challenging. In this analysis, we study the utility of the common carotid artery waveforms to distinguish true from pseudo-severe low-flow low-gradient aortic stenosis.This is an observational analysis that included patients who underwent a transthoracic echocardiogram (TTE) and duplex carotid ultrasonography (DCUS) and had low-flow, low-gradient aortic stenosis with reduced left ventricular ejection fraction on the index TTE (LVEF <50%, calculated aortic valve area (AVA) of ≤1.0 cm2, mean and peak gradient of <40 and <64 mmHg respectively and stroke volume index (SVi) < 35mL/m2). Patients were classified as pseudo-severe and true-severe aortic stenosis based on additional subsequent testing. Differences in various TTE and DCUS waveform parameters across the aortic valve and the common carotid artery were compared between the two groups.The study included 30 patients (60 carotid arteries). Fifteen patients were categorized as pseudo-severe and 15 as true severe aortic stenosis. There were no significant differences in calculated AVA, LVEF, SV/SVi and DVI in the two groups. Mean and peak gradient were higher in patients with true-severe aortic stenosis. Carotid acceleration time (cAT) was significantly prolonged in patients with true-severe compared to pseudo-severe aortic stenosis. A cAT ≥ 80ms was 83.3% sensitive and 83.3% specific for true-severe aortic stenosis.Carotid acceleration time may be used to distinguish true from pseudo-severe low-flow, low gradient aortic valve stenosis.