Patient selection process in the present study. Patient selection process in the present study. The flow chart shows grouping of patients based on the 2014 American Heart Association/American College of Cardiology valvular disease guideline. AS, aortic stenosis; HG, high-gradient; LF, low-flow; LG, low-gradient; LVEF, left ventricular ejection fraction; MG, mean gradient; NF, normal-flow; SVi, stroke volume index. Yugo Nara et al. Open Heart 2019;6:e000988 ©2019 by British Cardiovascular Society