(CCSP087) A NOVEL SIMPLE DOPPLER-ECHOCARDIOGRAPHIC PARAMETER TO ADJUDICATE STENOSIS SEVERITY IN LOW-GRADIENT AORTIC STENOSIS

Background: In patients with low-gradient (LG) aortic stenosis (AS), dobutamine stress echocardiography (DSE) or aortic valve calcium scoring by computed tomography is required to confirm AS severity and indication of intervention. We hypothesized that the mean transvalvular gradient to effective orifice area ratio (MG/EOA, in mmHg/cm2) measured at rest echocardiography predicts true severity of AS and clinical outcomes in patients with LG-AS. The objective of this study was to compare the diagnostic accuracy and prognostic value of the MG/EOA ratio in LG-AS patients.

METHODS AND RESULTS: The diagnostic accuracy of the MG/EOA ratio to predict true severe aortic stenosis (TSAS) was assessed in: i) an in vitro dataset obtained in a circulatory model and ii) an in vivo dataset collected in 198 patients recruited in the prospective observation cohort study TOPAS (NCT01835028) using receiver operating characteristic curve analysis. The prognostic value of this parameter was assessed using spline curve analysis and multivariate Cox proportional hazard regression, using a composite of aortic valve replacement or all-cause mortality at 2-years as clinical endpoint.
In LG-AS patients, the MG/EOA ratio at rest predicted TSAS with an AUC of 0.99 [0.98-1.00] in the in vitro dataset and 0.92 [0.87-0.95] in the in vivo dataset. In the in vivo dataset predominantly composed of patients with low flow state, the optimal cut-off of the MG/EOA ratio was 29 mmHg/cm2 at normal flow (percentage of correct classification: 95%) and 25 mmHg/cm2 (85%) at low flow conditions, as in the in vitro dataset (100%). In LG-AS patients, a MG/EOA ratio ≥ 23 mmHg/cm2 was associated with increased risk of the composite endpoint (unadjusted HR=2.16 [1.58-3.06], p< 0.001; adjusted HR=2.80 [1.94-4.03], p< 0.001). The net reclassification index (NRI) of the resting parameter MG/EOA was 0.57 (p < 0.001), which was similar to EOAproj (NRI=0.61, p< 0.001) measured by DSE.

Conclusion: In this study, we propose a new, simple parameter that can easily be obtained from a standard echocardiography and that is superior to other rest echocardiographic parameters and non-inferior to DSE parameters with respect to diagnostic accuracy and prognostic value in patients with LG-AS. This parameter can be useful in LG-AS to confirm the aortic stenosis severity and indication of intervention from the rest echocardiography and may thus avoid the use of additional tests such as DSE or aortic valve calcium scoring.