Abstract 17245: Assessment of Contractility and Afterload Mismatch as Determinants of Reduced Ejection Fraction in Severe Aortic Stenosis

Abstract

Background: Reduced LV ejection fraction (EF) in aortic stenosis (AS) is related to a decrease in contractility or afterload mismatch. Increase in afterload is due to reduced aortic valve area (AVA), changes in LV geometry and the characteristics of arterial vasculature.

Objective: To evaluate contractility and afterload mismatch as determinants of reduced EF in severe AS.

Methods: We studied 77 patients, age average 70 ± 10 years, 48 men, with severe AS (AVA < 1 cm²) and 63 normal control subjects with Doppler echocardiography. Contractility was assessed by midwall fractional shortening (mFS) - end-systolic stress (ESS) relation in control subjects, with regression equation: mFS = 28.15 - 0.12 x ESS , standard error of estimation (SEE) of 3.75 % (r=0.40 p< 0.001). For any ESS level, a value of mFS predicted by the regression equation below 2 SEE was considered as decreased contractility in patients with AS. Afterload mismatch was defined as EF < 50 % and contractility within normal range. Patients were divided into three groups: group 1, EF < 50 % and decreased contractility (n = 18), group 2, EF < 50 % and normal contractility (afterload mismatch) (n = 20 ) and group 3, EF ≥ 50 % and normal contractility (n = 39). Presence of heart failure (NYHA III-IV), symptoms (dyspnea I-II, angina, syncope), AVA, peak and mean gradient (PG, MG), valve resistance, energy loss index, valvulo-arterial impedance (Zva) and effective arterial elastance (Ea) were determined in three groups.

Results: see table There were not differences in AVA, valve resistance, energy loss index among three groups. In multivariate analysis Zva, Ea, PG and MG, were predictors of decreased contractility.

Conclusions: Patients with severe AS and reduced EF had similar proportion of decreased contractility, afterload mismatch and heart failure. Increase in vascular component of afterload evaluated by mean of Zva and E_a impacts significantly on contractility.