Prevalence, clinical and echocardiographic characteristics of various flow and gradient patterns in mild or moderate aortic stenosis with normal left ventricular ejection fraction

Abstract

Background/objectives: Paradoxical low-flow aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) has only been described in severe AS. Controversy surrounds prognosis and management but no studies have reported this phenomenon in mild or moderate AS. We investigated the prevalence of flow and gradient patterns in this population, characterising their clinical and echocardiographic profile.

Methods: Consecutive subjects (n=1362) with isolated AS: mild (n=462, aortic valve area≥1.5cm(2), 2.5m/s<aortic jet velocity≤3m/s) or moderate (n=900, 1cm(2)≤aortic valve area<1.5cm(2)) and normal LVEF (≥50%) were studied. Subjects with low-flow (stroke volume index<35ml/m(2)) were identified. Univariate and multivariate analyses were employed to compare the flow and gradient patterns.

Results: In mild AS, 130 (28%) had low-flow. Lower left ventricular mass index (LVMI) (97.0±28.5vs116.4±2.3g/m(2),p<0.001), higher percentage of concentric remodelling (40%vs6%,p<0.001) and hypertrophy (43%vs40%,p<0.001) and lower end-systolic wall stress (ESWS) (57.6±1.60vs67.7±19.6dyn/cm(2),p=0.014) were independently associated with low-flow. Similarly, in moderate AS, 297 (33%) had low-flow. Older age (73.4±14.8vs69.5±16.5,p=0.027), lower LVMI (88.6±25.9vs118.0±36.5,p<0.001), higher percentage of concentric remodelling (46%vs8%,p<0.001) and lower ESWS (59.9±18.3vs70.5±19.7,p<0.001) were independently associated with low-flow. Despite moderate AS, most had lower mean pressure gradients, especially subjects with concentric remodelling. In the entire cohort, low-flow patients had more concentric remodelling (43%vs7%,p<0.001) and less eccentric hypertrophy (2%vs27%,p<0.001) compared to normal flow.

Conclusions: Low-flow AS with normal LVEF is observed in mild or moderate AS, in up to a third of the cases. These patients had different LV structure compared to normal-flow, with more concentric remodelling. Further studies are warranted.

Keywords: Aortic stenosis; Echocardiography; Left ventricular ejection fraction; Low-flow; Mild–moderate.