Introduction Previous studies have shown only modest correlation between aortic valve area (AVA) and left ventricular mass in aortic stenosis (AS), likely due to the variable additional after-load from the aortic and systemic circulation.
Cardiac magnetic resonance (CMR) has developed sequences to measure turbulent kinetic energy (TKE) in the proximal aorta, derived from time resolved three-dimensional (4D) flow imaging. It represents energy dissipation and irreversible pressure loss. Work in the same patient cohort demonstrated peak TKE is higher in bicuspid than tricuspid AS, probably due to larger ascending aortas. We assessed peak systolic TKE in patients with wide ranging AS (mild to severe) and correlated it with left ventricular (LV) parameters.
Methods 22 patients with tricuspid AS (mean age 72.1 ± 8.6 years, mean indexed valve area (AVA) 0.55 ± 0.18cm2/m2) and 20 with bicuspid AS (age 65.2 ± 8.5, indexed AVA 0.77 ± 0.42 cm2/m2) were scanned. Peak systolic TKE was measured using specialist analysis software and systolic LV longitudinal strain with proprietary feature-tracking software.
Results LV mass index was the only measure of LV function that correlated with AVA: inverse correlation (r) = −0.404; p 0.006. Peak TKE had a stronger correlation with LV mass (r 0.53; p 0.001), especially in bicuspid AS (r 0.83; p 0.0001). Peak TKE also correlated with indexed LV end diastolic volume (r 0.486; p 0.003), stroke volume (r 0.564; p 0.0004) and stroke work (r 0.58; p 0.0003). This correlation was especially strong in BAV AS (Table 1). No correlation with LV ejection fraction or systolic longitudinal strain was found.
Conclusions Peak TKE is a promising tool to better understand the variable effects of AS on the LV, beyond simply severity of AS. The effect is particularly strong in bicuspid AS, who have larger aortas - the likely mechanism for increased TKE.
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