Impact of a Concomitant Subaortic Stenosis on the Assessment of the Severity of an Aortic Valve Stenosis: An In-Vitro Study

Aortic valve stenosis (AS) is an important cardiovascular disease affecting between 2 and 7% of the elderly population in industrialized countries. Patients with AS may experience angina pectoris. Angina is associated with a marked increase in the risk of sudden death in AS patients. AS often coexists with subaortic stenosis (SAS), which is generally caused by a protrusion of the hypertrophied left ventricular outflow tract (LVOT) just below the aortic valve. The aim of this study was to determine from the valve effective orifice area (EOA) if the SAS might potentially interfere with the assessment of AS severity. We have examined the effect of different degrees of SAS (from normal to very severe SAS) on EOA measured from orifices mimicking different AS severities and from a homemade AS model realized from a bioprosthetic aortic valve. For the most severe AS, the SAS severity had no impact on the measured EOA. On the contrary, for the less severe AS, beyond a SAS severity of 50%, the AS severity was progressively overestimated and reached a reduction of about 60% of EOA for a SAS severity of 90%. We have shown that the presence of a concomitant SAS may cause an overestimation of the hemodynamic severity of AS. The degree of overestimation is more important in less severe AS. Hence, the presence of SAS may lead the clinician to erroneously conclude that the AS is severe and that aortic valve replacement is indicated.