Optimal timing of valve replacement in asymptomatic severe aortic stenosis.

Patients with asymptomatic severe aortic stenosis (AS) constitute a heterogeneous group which includes not only certain cases who are at high risk of sudden death and valve-related heart failure, but also those at low risk for these events. Degenerative AS, which includes a majority of patients with AS, is characterized by stricture of the valve, increased arterial stiffness, and diverse left ventricular response to the valvular plus arterial vascular load. In addition to using traditional primary parameters, the severity of AS and the total left ventricular load should be assessed using new measures such as energy loss index and valvulo-arterial impedance. Natriuretic peptide levels and global longitudinal strain imaging may also be used as secondary parameters to obtain information about left ventricular systolic function, although these parameters do not correlate with the severity of AS. Exercise stress testing and exercise echocardiography are also beneficial when assessing the patient if they are symptomatic, and for determining valvular and left ventricular contractile reserves. The aim of this review was to emphasize the importance of risk stratifications in asymptomatic severe AS cases, and to assess the severity of AS using not only conventional methods but also new methods on which much emphasis has been placed during recent years.