Myocardial work index in severe aortic stenosis and its relationship with staging classification of the associated cardiac damage: results of a large transcatheter valve replacement candidate cohort
Authors: Turschl T K , Ladanyi Z , Balint T , Nagy D , Fabian A , Tokodi M , Papp R , Szigethi T , Molnar L , Zima E , Nagy A , Kovacs A , Merkely B , Ruppert M , Lakatos B K 
Published: January 2025

Abstract

Background
With increasing life expectancy and aging of the population, aortic valve stenosis (AS) is now the most prevalent valvular disease in developed nations. Left ventricular (LV) functional assessment is challenging in this pressure-overloaded disease state, however, myocardial work analysis may overcome this issue by proving load-adjusted measures of LV function. Notably, long-standing severe AS results in progressive damage of the heart, starting from left ventricular (LV) remodeling to significant backward effects eventually leading to manifest right ventricular dysfunction. Myocardial work parameters, being less load-dependent markers of LV function may follow the extent of cardiac damage. However, the relationship of cardiac damage staging and myocardial work measures is scarcely investigated.

Purpose
Accordingly, we aimed to examine the relationship of myocardial work indices and AS staging in a transcatheter aortic valve replacement (TAVR) candidate AS cohort.

Methods
296 patients (79±7 years, 41% female) with severe AS were enrolled. Medical history was obtained and we performed detailed echocardiography prior to TAVR. Aortic valve area (AVA) was calculated using the continuity equation. LVEDVi was measured using the biplane Simpson method. Based on the echocardiographic data, we determined the extent of cardiac damage caused by AS, patients were classified as Stage 0 (no cardiac damage), Stage 1 (LV damage), Stage 2 (mitral valve or left atrial damage), Stage 3 (pulmonary artery vasculature or tricuspid valve damage), or Stage 4 (right ventricular damage). We determined the LV ejection fraction (EF) and via speckle-tracking echocardiography global longitudinal strain (GLS) was also measured. Then, utilizing left ventricular volume curves derived from systolic blood pressure and mean transaortic gradient, we calculated global myocardial work index (GWI).

Results
14 (5%) patients were classified as Stage 0, 61 (21%) as Stage 1, 132 (45%) as Stage 2, 16 (5%) as Stage 3, and 73 (25%) as Stage 4. EF (from Stage 0-4: 61±6 vs. 48±12 vs. 48±11 vs. 45±14 vs. 40±15%, p≤0.01) and GLS (-16.9±3.4 vs.-13.2±3.3 vs. -12.6±3.8 vs. -11.8±4.8 vs. -9.8±4.4%, p≤0.01) only differed in Stages 3 and 4, while GWI values formed a more defined spectrum through the Stages (2481±543 vs. 1726±588 vs. 1717±686 vs. 1581±867 vs. 1185±692 mmHg%, p≤0.001). Using multivariate regression analysis, examining relevant clinical and echocardiographic parameters, age (β=0.15, p=0.02), cardiac damage stage (β=-0.19, p≤0.01), AVA (β=0.21, p≤0.01), LVEDVi (β=-0.33, p≤0.001) and having a pacemaker (β=-0.15, p=0.01) were independent predictors of GWI (R²= 0.41, p≤0.0001).

Conculsions
LV GWI show distinct changes throughout the spectrum of cardiac damage associated with severe AS. Beyond age, AVA, LVEDVi and having a pacemaker, cardiac damage stage is also an independent determinant of GWI in this population.