The Incremental Value of Valvuloarterial Impedance in Evaluating the Results of Transcatheter Aortic Valve Implantation in Symptomatic Aortic Stenosis

Abstract

Valvuloarterial impedance (Z(va)) can estimate the global hemodynamic load on the left ventricle in patients with severe aortic stenosis better than the standard indexes, as shown in previous studies. In fact, Z(va) can estimate global left ventricular hemodynamic load as the sum of valvular and vascular loads. The aim of this study was to evaluate the acute improvement of left ventricular performance in patients with symptomatic aortic stenosis after transcatheter aortic valve implantation (TAVI) using Z(va). One hundred two consecutive patients who underwent TAVI were submitted to transthoracic echocardiography immediately before and after aortic valve implantation, together with invasive hemodynamic measurements. After TAVI, immediate reductions in the transaortic peak pressure gradient (P < .0001) and mean pressure gradient (P < .0001) and a concomitant increase in aortic valve area (P < .0001) were seen on echocardiography. Left ventricular ejection fraction significantly increased immediately after TAVI in all patients (from 48.9 ± 10.3% to 52.1 ± 11.1%, P < .0001). Regarding global left ventricular hemodynamic load, acute and significant reductions in end-systolic meridional wall stress (from 82.7 ± 42.6 to 57.8 ± 30.1 kdyne · cm(-2), P < .0001) and in Z(va) (from 6.81 ± 2.51 to 5.38 ± 2.13 mm Hg · mL(-1) · m(-2), P < .0001) were observed. Furthermore, patients who died at 6-month follow-up had higher baseline Z(va) values compared with those who were alive at 6-month follow-up (8.13 ± 3.08 vs 6.41 ± 2.12 mm Hg · mL(-1) · m(-2), P < .004). TAVI is characterized by an immediate enhancement of global left ventricular hemodynamic performance, as demonstrated by an acute Z(va) improvement, even in patients with low baseline ejection fractions.