Novel Echocardiography-Derived Left Ventricular Stiffness Index in Low-Flow Versus Normal-Flow Severe Aortic Stenosis with Preserved Left Ventricular Ejection Fraction

Abstract

Background Paradoxical low-flow (LF) severe aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) may have poorer prognosis than normal-flow (NF) AS, though its pathophysiology remained unclear. In particular, LV stiffness has not been compared between LF vs NF. We used a novel echocardiography-derived index of LV stiffness to compare between these groups. Consecutive patients with medically-managed isolated severe AS (aortic valve area < 1 cm 2) and preserved LVEF (>50%) were studied. Echocardiographic LV stiffness index was measured by a method previously validated against cardiac catheterization. We compared LF (stroke volume index, SVI < 35 ml/m 2) and NF severe AS. Of the 352 patients, 121 (34%) were LF. Both LF and NF groups had similar demographics, valve areas and indices. Compared to NF, LF severe AS had higher LV stiffness indices (>0.11 ml −1 OR 3.067, 95% CI 1.825-5.128, p < 0.001). Increased LV stiffness was associated with concentric remodelling and more severe diastolic dysfunction, especially in LF AS. An LV stiffness index of > 0.11 ml −1 was independently associated with increased mortality, after adjusting for age, clinical and echocardiographic parameters (HR 2.283 95% CI 1.318-3.968, p = 0.003). Non-invasive echocardiographic-derived index of LV stiffness may be important in LF AS. Increased LV stiffness was related to LV concentric remodelling and diastolic dysfunction, and associated with poorer clinical outcomes in medically-managed AS. Significant differences in echocardiographic profiles exist between paradoxical low-flow (LF) and normal-flow (NF) severe aortic stenosis (AS). This may be due to differences in pathophysiological processes in the natural history of LF compared to NF AS. Of note, left ventricular (LV) stiffness has not been evaluated in AS. Conventional measurement of LV stiffness involves using invasive cardiac catheterization and determination of the end-diastolic pressure-volume relationship by pressure-volume loop analysis 1. This is impractical for routine serial evaluation in AS as it requires invasive cardiac catheterization 2,3. AS remains an important disease because of its high prevalence. It affects approximately 5% of patients over 75 years of age, and is associated with reduced survival 4,5. LF AS (LV stroke volume index (SVI) < 35 mL/m 2) despite preserved left ventricular ejection fraction (LVEF), termed "paradoxical low-flow", has been increasingly recognised as a subgroup of severe AS that portends a worse prognosis compared to normal-flow 6. However, the differential effects of the aortic valve pathology on the LV in LF compared to NF AS, particularly LV stiffness, remains to be elucidated 7-9 .

Can we explore AF–pacemakers’ relationship using clinical and echocardiographic parameters in patients with permanent pacemaker? (Echocardiography and subclinical AF in permanent pacemaker)

“…We found that EDV and SVI had –ve correlation with LV stiffness index and + ve correlation with DWS, in agreement with Ngiam et al [ 26 ] who stated that the higher the LV stiffness, the lower EDV and SVI. On multivariable analysis we found that AF was only associated with reduced DWS and increased LV stiffness index, which are contributing factors in subtle diastolic dysfunction, patients with reduced DWS (< 0.33) and high LV stiffness index (> 0.13 ml −1 ) had a higher risk to develop AF.…”

The constricting effect of reduced coronary artery compliance on the left ventricle is an important cause of reduced diastolic function in patients with coronary heart disease

“…The tangent slope of any point on this curve (dP/dV) is called the left ventricular lumen stiffness. And K is the slope of the linear relationship between ventricular stiffness and ventricular pressure, reflecting left ventricular Passive diastolic function [ 17 , 18 ]. Coronary pressure was measured by end-diastolic coronary volume (CEDV), end-systolic coronary volume (CESV), maximum rate of increase in coronary pressure (C+dp/dtmax).…”