NPPB and aortic stenosis: These include LVEF < 50%, low-surgical-risk patients with severe AS (mean gradient >60 mmHg, aortic velocity >5 m/s), or severe AS with BNP level >3 times its normal range, or severe AS with an increase in aortic velocity >0.3 m/s per year, or decreased exercise tolerance or a drop in systolic blood pressure (SBP) >20 mmHg from baseline to peak exercise during carefully supervised bike or treadmill testing (using cardiopulmonary exercise testing protocols or standard/modified BRUCE protocols) (35).