Doppler Imaging in Aortic Stenosis: The Importance of the Nonapical Imaging Windows to Determine Severity in a Contemporary Cohort

Background: Although the highest aortic valve velocity was thought to be obtained from imaging windows other than the apex in about 20% of patients with severe aortic stenosis (AS), its occurrence appears to be increasing as the age of patients has increased with the application of transcatheter aortic valve replacement. The aim of this study was to determine the frequency with which the highest peak jet velocity (V_max) is found at each imaging window, the degree to which neglecting nonapical imaging windows underestimates AS severity, and factors influencing the location of the optimal imaging window in contemporary patients. Methods: Echocardiograms obtained in 100 consecutive patients with severe AS from January 3 to May 23, 2012, in which all imaging windows were interrogated, were retrospectively analyzed. AS severity (aortic valve area and mean gradient) was calculated on the basis of the apical imaging window alone and the imaging window with the highest peak jet velocity. The left ventricular-aortic root angle measured in the parasternal long-axis view as well as clinical variables were correlated with the location of highest peak jet velocity. Results: V_max was most frequently obtained in the right parasternal window (50%), followed by the apex (39%). Subjects with acute angulation more commonly had V_max at the right parasternal window (65% vs 43%, P = .05) and less commonly had V_max at the apical window (19% vs 48%, P = .005), but V_max was still located outside the apical imaging window in 52% of patients with obtuse aortic root angles. If nonapical windows were neglected, 8% of patients (eight of 100) were misclassified from high-gradient severe AS to low-gradient severe AS, and another 15% (15 of 100) with severe AS (aortic valve area < 1.0 cm²) were misclassified as having moderate AS (aortic valve area > 1.0 cm²). Conclusions: In this contemporary cohort, V_max was located outside the apical imaging window in 61% of patients, and neglecting the nonapical imaging windows resulted in the misclassification of AS severity in 23% of patients. Aortic root angulation as measured by two-dimensional echocardiography influences the location of V_max modestly. Despite increasing time constraints on many echocardiography laboratories, these data confirm that routine Doppler interrogation from multiple imaging windows is critical to accurately determine the severity of AS in contemporary clinical practice.