Left ventricular blood flow kinetic energy is associated with the six-minute walk test and left ventricular remodelling post valvular intervention in aortic stenosis

Abstract

Background: Left ventricular (LV) kinetic energy (KE) assessment by four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) may offer incremental value over routine assessment in aortic stenosis (AS). The main objective of this study is to investigate the LV KE in patients with AS before and after the valve intervention. In addition, this study aimed to investigate if LV KE offers incremental value for its association to the six-minute walk test (6MWT) or LV remodelling post-intervention. Methods:We recruited 18 patients with severe AS. All patients underwent transthoracic echocardiography for mean pressure gradient (mPG), CMR including 4D flow and 6MWT. Patients were invited for post-valve intervention follow-up CMR at 3 months and twelve patients returned for follow-up CMR. KE assessment of LV blood flow and the components (direct, delayed, retained and residual) were carried out for all cases.LV KE parameters were normalised to LV end-diastolic volume (LVEDV).Results: For LV blood flow KE assessment, the metrics including time delay (TD) for peak E-wave from base to mid-ventricle (14±48 vs. 2.5±9.75 ms, P=0.04), direct (4.91±5.07 vs. 1.86±1.72 μJ, P=0.01) and delayed (2.46±3.13 vs. 1.38±1.15 μJ, P=0.03) components of LV blood flow demonstrated a significant change between pre-and post-valve intervention. Only LV KEi EDV (r=−0.53, P<0.01), diastolic KEi EDV (r=−0.53, P<0.01) and E wave KEi EDV (r=−0.38, P=0.04) demonstrated association to the 6MWT. However, Pre-operative LV KEi EDV (r=0.67, P=0.02) demonstrated association to LV remodelling post valve intervention. Conclusions: LV blood flow KE is associated with 6MWT and LV remodelling in patients with AS. LV KE assessment provides incremental value over routine LV function and pressure gradient (PG) assessment in AS.

Analysis of right ventricular flow with 4-dimensional flow cardiovascular magnetic resonance imaging in patients with pulmonary arterial hypertension

“…Stoll et al used 4D flow CMR in patients with ischemic or dilated cardiomyopathy and observed a decrease in the volume and kinetic energy of direct flow (DF) compared with healthy controls (10). Elhawaz et al (11) indicated that the kinetic energy of left ventricular (LV) blood flow was associated with the 6-minute walk test and LV remodeling after valvular intervention in patients with aortic stenosis. Fredriksson et al (12) reported that RVDF had a larger volume and possessed a higher presystolic kinetic energy than the other flow components in healthy people.…”

Pathophysiology, emerging techniques for the assessment and novel treatment of aortic stenosis

“… 77 Measurements of LV blood flow kinetic energy have also been associated with ventricular remodelling and an inverse correlation to exercise capacity. 78 The ability of CMR to assess these components can lead to greater risk stratification and prediction of clinical outcomes, guiding management prior to and following treatment. Although these findings are derived from small sample sizes, 77 78 larger clinical studies are warranted to evaluate the prognostic capabilities of CMR and to therapeutically target these biomarkers to improve patient quality of life.…”

“…In particular, greater magnitudes of wave reflections and reduced arterial compliance are associated with decompensation and a poorer clinical course following valve replacement 77. Measurements of LV blood flow kinetic energy have also been associated with ventricular remodelling and an inverse correlation to exercise capacity 78. The ability of CMR to assess these components can lead to greater risk stratification and prediction of clinical outcomes, guiding management prior to and following treatment.…”