LV flow kinetics and myocardial deformation following acute infarction: additional predictive value of CMR 4D flow for LV remodeling post-STEMI.

Abstract

Background: The exact mechanism underlying myocardial maladaptive changes post ST-elevation myocardial infarction (STEMI) remains unclear.

Objectives: To assess the impact of the tissue-flow interaction on the development of adverse cardiac remodeling 12 months (M) after acute STEMI.

Materials and methods: 49 first-STEMI patients (M:F=26:13; mean age=58±10) prospectively underwent 3T CMR acutely, at 3M and 12M post-STEMI. The CMR protocol included left ventricular (LV) cine-images for LV end-diastolic (LVEDV) and end-systolic (LVESV) volumes, stroke volume (SV) and ejection fraction (LVEF); 4D-flow; LGE imaging. The 3M outcome measures included: 4D-flow derived LV flow kinetic energy indexed to EDV (KE_iEDV) and functional flow components [LV- KE_iEDV, minimal- KE_iEDV, diastolic- KE_iEDV, and residual volume (RV), retained inflow (RI), delayed ejection (DE), direct flow (DF)]; global radial, circumferential and longitudinal strain (GRS, GCS, GLS) by feature tracking (FT); infarct size (IS). Adverse LV remodeling (LV_remod) was defined by a ≥ 20% increase in LVEDVi at 12M from baseline, in opposition to the non-remodeling group (LV_non-remod). Association between SV, FT-strain, KE and 4D flow parameters were assessed, as well as predictors of adverse remodeling at 12M post-STEMI.

Results: There were 23 LV_remod patients. At 3M post-STEMI, LV_remod patients had significantly reduced LVEF, increased IS, abnormal FT-strain, systolic KE_iEDV, DF and RV compared to LV_non-remod patients. Ther was no significant difference in SV between the 2 groups. FT-strain parameters significantly correlated with DF (GRS: r=0.62; GCS: r=-0.67; GLS: r=-0.58, all p<0.001); RV (GRS: r=-0.56; GCS: r=0.51; GLS: r=0.53, all p<0.001); Peak-A-wave KE_iEDV (GRS: r=0.38, p=0.008; GCS: r=-0.30, p=0.038; GLS: r=-0.29, p=0.04); Systolic KE_iEDV (GRS: r=0.31, p=0.033, GLS: r=-0.35, p=0.012). DF outperformed conventional LV function parameters (SV and LVEF) in the LV_remod prediction. DF and IS were the only independent predictors of 12M adverse remodeling after adjustment for LVEF, SV, FT-strain and KE_iEDV parameters.

Conclusions: Our study suggests a potential early interaction between FT-strain and 4D-flow parameters post-STEMI leading to the development of adverse remodeling. Within the limitations of our sample size, DF and IS were independent predictors of LV remodelling after adjustment for LVEF, SV, FT-strain and KE parameters. These findings suggest that these parameters may contribute to further risk stratification at 3M for the development of adverse remodeling at 12M post-STEMI, above conventional LV function parameters. Larger studies are needed to confirm these results.