Aortic 4D flow CMR for the assessment of hemodynamics in aortic stenosis: association with markers of cardiac decompensation and remodeling.

Aortic stenosis (AS) induces complex alterations in ascending aortic flow, including increased turbulent kinetic energy (TKE), altered velocity profiles, and changes in flow organization, which can be quantified using four-dimensional (4D) flow cardiovascular magnetic resonance (CMR). The physiological relevance of these flow-derived parameters with respect to left ventricular (LV) adaptation remains incompletely understood. We investigated the associations between 4D flow CMR-derived hemodynamic metrics and established markers of LV decompensation and remodeling in patients with AS. Fifty-nine patients with AS (70 ± 14 yr) underwent 4D flow CMR using a Bayesian multipoint phase-contrast sequence with k-t PCA acceleration and three velocity-encoding steps in each direction. Quantified parameters included peak TKE, stroke volume-normalized systolic TKE (normalized TKEsys), peak velocity, jet angle, relative flow displacement, and mean helicity. Associations with NT-proBNP and indexed LV mass were analyzed. Peak TKE, normalized TKEsys, and peak systolic velocity were significantly associated with both indexed LV mass and NT-proBNP, whereas mean helicity was associated with indexed LV mass only. In contrast, jet angle and flow displacement showed no relationship with either marker of LV decompensation and remodeling. During long-term follow-up, no 4D flow CMR parameter was associated with adverse clinical events, likely due to timely valve replacement in most patients. In conclusion, these findings indicate that flow energetics-particularly TKE and peak systolic velocity-most closely capture the hemodynamic burden imposed on the LV supporting their physiological relevance in AS. Isolated descriptors of flow geometry, in contrast, have not shown to reflect maladaptive LV remodeling.NEW & NOTEWORTHY This study used advanced four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) to investigate alterations in aortic flow of patients with aortic stenosis and its relation to left ventricular remodeling and decompensation. It shows that turbulent kinetic energy, which is a measure of irreversible energy loss downstream of a stenotic valve, and peak flow velocity are the characteristics, which best capture the hemodynamic burden imposed on the left ventricle (LV). In contrast, geometric flow descriptors such as jet angle and flow displacement lacked physiological relevance.