Comparative prognostic value of different echocardiographic parameters of the subpulmonary left ventricle in adults with a systemic right ventricle
Authors: Constantine A , Surkova E , Alviento M , Austria-Manlapig A , Xu Z , Segura T , Bispo D , Dimopoulos K , Li W 
Published: November 2023

Abstract

Introduction
Adults with complex congenital heart disease and a systemic right ventricle (SRV) are at increased risk of SRV dysfunction, heart failure, and premature death. In the systemic left ventricle (LV), impaired global longitudinal strain (GLS) is a strong predictor of adverse outcome. In the subpulmonary LV, however, echocardiographic assessment lacks standardisation and the relative prognostic significance of metrics of subpulmonary LV function remain unknown.

Purpose
To assess the correlation and relative prognostic power of quantitative metrics of subpulmonary LV function in adults with an SRV.

Methods
All adults with an SRV who underwent echocardiography in 2011-2019 at our specialist centre and had sufficient data for quantitative multiparametric subpulmonary LV assessment were included. LV systolic function was assessed by fractional area change (FAC), 4-chamber global longitudinal strain (GLS) and free wall longitudinal strain (FWLS). Linear regression was used to assess the correlation between echocardiographic variables of subpulmonary LV function. Cox regression analysis was used to assess the relation between echocardiographic predictors and the combined endpoint of death or transplantation. TimeROC analysis was performed to assess risk variable performance.

Results
In total, 120 patients (43.5±12.1 years, 60.0% male, 37.5% congenitally corrected transposition of the great arteries) were included. Most patients (94, 79.0%) were in NYHA functional class I/II and two-thirds (79, 66.4%) were receiving ≥1 heart failure therapy.
One half of patients (63, 52.5%) had at least moderate systolic SRV dysfunction at baseline assessment with a median SRV FAC of 27[22-32]%. Subpulmonary LV function was visually preserved in most patients (98, 81.7%), with a LV FAC of 47.0[40.0-52.9]%. Median GLS was -15.2[-19.7–11.8]% and LV FWLS -19.9[-24.4–12.8]%. There was a weak correlation between LV FAC and GLS (r=0.25).
During a median follow-up of 4.9[3.4-5.6] years, 24(20.0%) patients died and 3(2.5%) underwent heart or heart-lung transplantation. The 5-year transplant-free survival was 78.9%, (95%CI: 71.7-86.8%). On univariable Cox analysis, LV FAC (/5%, HR 0.55, 95%CI:0.47-0.65, p&lt;0.0001) and GLS (/5%, HR 1.6, 95%CI:1.1-2.31, p=0.01), but not LV FWLS (/5%, HR 1.25, 95%CI:0.99-1.58, p=0.06) emerged as predictors of death or transplantation. LV GLS did not remain predictive in a bivariable model including LV FAC. LV FAC outperformed GLS on timeROC analysis (5-year AUC 0.87 vs. 0.64, p&lt;0.0001; Figure).

Conclusions
Impaired systolic function of the subpulmonary LV strongly associated with mortality and heart or heart-lung transplantation in adults with an SRV. Both LV FAC and GLS are related to outcomes and should be a part of comprehensive echo assessment. LV FAC, a marker longitudinal and radial contraction, may better reflect pathophysiological mechanisms of subpulmonary LV failure and has greater prognostic significance in SRV patients.5-year ROC curves of LV FAC and GLS