Correlations between ventricular arterial coupling and myocardial work indices in healthy subjects: a speckle tracking echocardiography study
Authors: Mandea M C , Beladan C C , Cergan B , Nita B , Calin A , Rosca M , Enache R , Botezatu S B , Popescu B A 
Published: January 2025

Abstract

Background
The interaction between left ventricular (LV) function and arterial afterload, defined as ventricular-arterial coupling (VAC), is a key determinant of cardiovascular (CV) performance. The echocardiographic assessment of VAC by the ratio of effective arterial elastance (Ea) to LV end-systolic elastance (Ees) is the most used non-invasive method. Recently, the myocardial work index (MWI) is proposed as a novel VAC non-invasive method. This method, integrating LV pressure (using a brachial cuff), and LV global longitudinal strain (GLS) by speckle tracking echocardiography (STE) to derive pressure-strain loops (PSL), provides a loading-independent evaluation of myocardial systolic performance.

Purpose
To assess the relationships between VAC, assessed by the Ea/Ees ratio, MW indices, and echocardiographic parameters of LV function in healthy adult subjects.

Methods
Healthy adult volunteers, without CV risk factors or any medical history, were prospectively enrolled (2019-2024). Age, height, weight, blood pressure (BP) and an ECG tracing to confirm the sinus rhythm were recorded at the time of the comprehensive echocardiogram in all subjects. Global MW indices - index (GWI), constructive (GCW), efficiency (GWE), and wasted (GWW) - were estimated using a commercially available software, from a non-invasive LVPSL, based on STE-derived GLS and estimated LV pressure. The Ea and Ees were expressed as end-systolic pressure (ESP) divided by stroke volume (SV)(ESP/SV) and ESP divided by end-systolic volume (ESP/ESV). VAC was calculated with the simplified formula Ea/Ees =ESV/SV (SV derived from the Biplane method). Off-line data analysis was performed with a dedicated software by a single experienced investigator.

Results
The study group included 65 subjects (55% males, mean age 33±12 years). The univariate analysis showed significant inverse correlations between Ea/Ees and age, GWI, GCW, GWE, GLS. Ea/Ees correlated with LVSVi and LVEF, as expected. Among MW indices, GWI was the only correlated with age (p&lt;0.001, r= 0.44). Significant correlations were found between MW indices and conventional parameters of LV size and function: GWI with E/e’average (p=0.04, r=0.26), LV mass index (LVMi) (p=0.01, 3=0.35), LVEF (p&lt;0.001, r=0.48); GCW with LVMi (p=0.04, r=0.28) and LVEF (p&lt;0.001, r=0.44). The only correlate of GWW and GWE was LV peak strain dispersion by STE. All MW indices correlated with BP and GLS as expected. On multivariable analysis, GWI was the only independent correlate of Ea/Ees(p&lt;0.001, standardized coefficient β=-0.42). Conclusions In a population of healthy individuals GWI emerged as the only independent correlate of the VAC ratio derived from conventional echocardiography. Both GWI and VAC ratio were age related. Our results suggest that VAC ratio and GWI are complementary in their ability to characterize the complex interplay between myocardial function and arterial system. The added value of GWI in this role deserves further evaluation.
Correlation between GWI and VAC ratio
Univariate correlates of the VAC ratio