Abstract 13853: Systolic Function and the Transvalvular Mean Gradient in Patients with Severe Aortic Stenosis: Role of Left Ventricular Twist and Longitudinal Systolic Strain
Background: In patients with severe aortic stenosis (AS) (AVA <1.0 cm2), a low transvalvular mean gradient (MG) portends a worse prognosis. A low MG is associated with a low flow state, which is often thought to be due to reduced LV function. However, the relationship between novel indices of LV function and MG has not been explored.
Objective: To examine how LV twist and longitudinal systolic strain affect the MG in patients with severe AS and preserved (≥50%) vs. reduced (<50%) ejection fraction (EF).
Methods: Data were prospectively collected on 168 patients with severe AS (indexed AVA [AVAi] < 0.6 cm2/m2). A linear regression model investigated the association between MG and LV systolic function variables (EF <50%, longitudinal systolic strain, twist, stress-corrected midwall shortening), LV preload and remodeling variables (sex, diabetes, LV end-diastolic dimension index, E/e', LV mass index, age, BMI, prior infarct, mitral regurgitation severity), AVAi, and vascular afterload variables (mean arterial pressure, systemic arterial compliance, systemic vascular resistance, history of hypertension). The model also explored interaction variables for reduced EF and each of the other LV systolic function variables.
Results: A low MG (<40 mmHg) was observed in 77% of patients with EF <50% (n=66) and 40% of patients with EF ≥50% (n=102). In the multivariable model, EF <50% was associated with a lower MG (ß=-17.8, p=0.019) and there was a trend between reduced stress-corrected midwall shortening and a lower MG (p=0.08) (R2=0.78). There were significant interactions between EF and both systolic strain and twist (p<0.05). In stratified analyses, in patients with EF ≥50%, a lower MG was associated with reduced twist (p=0.005), but not systolic strain; whereas in those with EF <50%, a lower MG was associated with reduced systolic strain (p<0.001), but not twist.
Conclusions: In patients with severe AS, a low MG is common and associated with reduced EF. However, novel indices of systolic function (LV twist and longitudinal systolic strain) appear to influence the MG in a manner that depends on EF. These findings may impact future studies that employ these novel echocardiographic indices and increase understanding of the pathophysiology of a low MG in those with severe AS.
- © 2011 by American Heart Association, Inc.