We have entered a new era in understanding degenerative aortic stenosis in elderly patients. With the aging of the US population and the progressive decrease in coronary heart disease prevalence in the past 50 years, aortic stenosis has become a major cardiac concern. New perspectives of the disease now lead us to see the condition in terms of the response of the left ventricle and of systemic features, rather than just in terms of the valve area itself. A new classification of aortic stenosis recognizes 4 categories based on flow state (normal or low) and valve gradient (high or low). "Paradoxical" low-flow, low-gradient stenosis has a dismal prognosis in spite of a normal left ventricular ejection fraction. New measures of aortic flow and the response of the left ventricle provide new insights into the treatment of patients with this condition.