Direct comparison of severity grading assessed by two-dimensional, three-dimensional, and doppler echocardiography for predicting prognosis in asymptomatic aortic stenosis

Background: Reliable assessment of aortic stenosis (AS) severity relies on stroke volume (SV) determination using Doppler echocardiography, but it can also be estimated with two-dimensional/three dimensional echocardiography (2DE/3DE). The aim of this study was to compare SV measurements and AS subgroup classifications among the three modalities and determine their prognostic strength in asymptomatic AS.

Methods: We prospectively enrolled 359 patients with asymptomatic AS. SV was determined using three methods, and the patients were divided into four AS subgroups according to indexed aortic valve area (iAVA) and SV index (SVI) determined by each method and mean pressure gradient. The primary end point was major adverse cardiovascular events (MACEs), which included cardiac death, ventricular fibrillation, heart failure, and aortic valve replacement. We also assessed the presence or absence of upper septal hypertrophy.

Results: Doppler-derived SVI was significantly larger than that derived from 2DE/3DE with modest correlations (r = 0.33 and 0.47). Thus, group classification varied substantially by modality. During the median follow-up period of 17 months, 112 patients developed a major adverse cardiovascular event. Although iAVA assessed by Doppler echocardiography had a significantly better net reclassification improvement compared with iAVA by 2DE or 3DE, prognostic values were nearly identical among the three methods. Ventricular septal geometry affected the accuracy of risk stratification.

Conclusions: AS severity grading varied considerably according to the methods applied for calculating SV. Thus, SV measurements are not interchangeable, even though their prognostic power is similar. Hence, examiners should select one of the three methods to assess AS severity and should use the same method in longitudinal examinations.