A novel echocardiographic hemodynamic index for predicting outcome of aortic stenosis patients following transcatheter aortic valve replacement

OBJECTIVE: Transcatheter aortic valve replacement (TAVR) reduces left ventricular (LV) afterload and improves prognosis in aortic stenosis (AS) patients. However, LV afterload consists of both valvular and arterial loads, and the benefits of TAVR may be attenuated if the arterial load dominates. We proposed a new hemodynamic index, the Relative Valve Load (RVL), a ratio of mean gradient (MG) and valvuloarterial impedance (Zva), to describe the relative contribution of the valvular load to the global LV load, and examined whether RVL predicted patient outcome following TAVR. METHODS: A total of 258 patients with symptomatic severe AS (indexed aortic valve area (AVA)<0.6cm2/m2, AR≤2+) underwent successful TAVR at the University of Ottawa Heart Institute and had clinical follow-up to 1-year post-TAVR. Pre-TAVR MG, AVA, percent stroke work loss (%SWL), Zva and RVL were measured by echocardiography. The primary endpoint was all cause mortality at 1-year post TAVR. RESULTS: There were 53 deaths (20.5%) at 1-year. RVL≤7.95ml/m2 had a sensitivity of 60.4% and specificity of 75.1% for identifying all cause mortality at 1-year post-TAVR and provided better specificity than MG<40 mmHg, AVA>0.75cm2, %SWL≤25% and Zva>5mmHg/ml/m2 despite equivalent or better sensitivity. In multivariable Cox analysis, RVL≤7.95ml/m2 was an independent predictor of all cause mortality (HR 3.2, CI 1.8-5.9; p<0.0001). RVL≤7.95ml/m2 was predictive of all cause mortality in both low flow and normal flow severe AS. CONCLUSIONS: RVL is a strong predictor of all-cause mortality in severe AS patients undergoing TAVR. A pre-procedural RVL≤7.95ml/m2 identifies AS patients at increased risk of death despite TAVR and may assist with decision making on the benefits of TAVR.