Evaluation of 4D Flow MRI-Derived Aortic Hemodynamics and Their Relationships With Left Ventricular Remodeling in...

Identifying factors associated with left ventricular (LV) remodeling is important for risk stratification of patients with moderate aortic stenosis (AS). The aim of this preliminary study was to explore aortic hemodynamics in these patients and assess their relationships with LV remodeling using four-dimensional (4D) flow magnetic resonance imaging (MRI).

Data from 17 patients with moderate AS involving the tricuspid aortic valves and normal LV ejection fraction (EF > 55%) were analyzed. All patients underwent 4D flow MRI of the ascending aorta and cardiac magnetic resonance (CMR) on the same day within 1 month of being diagnosed with moderate AS by transthoracic Doppler echocardiography. 4D flow MRI aortic parameters, including turbulent kinetic energy (TKE), both total and peak; peak wall shear stress (WSS); and the vortex and helix flow severity, were assessed. CMR measures comprised LV structure and function, late gadolinium enhancement (LGE), myocardial native T1 mapping, and extracellular volume fraction.

The minimum and maximum values of total TKE, peak TKE, and peak WSS were 39.4/160.3 mJ, 876.6/2059.6 J/m³, and 2.0/4.9 Pa, respectively. More than 50% of the patients had vortex and helix flow of Grade 2. Peak TKE significantly correlated with LV end-diastolic volume index (r = 0.675, p = 0.003), LV end-systolic volume index (r = 0.666, p = 0.003), and LV mass index (r = 0.653, p = 0.004). LGE was not observed, and peak TKE also showed an inverse correlation with native T1 value (r = -0.571, p = 0.017).

Among patients with moderate AS, 4D flow MRI revealed heterogeneous aortic hemodynamic profiles and peak TKE was a significant hemodynamic parameter related to early LV remodeling. However, these findings need to be confirmed in further studies with larger sample sizes and a long-term serial follow-up data.