Prevalence, Mechanisms, and Prognostic Impact of Effort Intolerance in Patients With Asymptomatic/Minimally Symptomatic Aortic Stenosis

Abstract

Background: We aimed to investigate the prevalence and prognostic impact of effort intolerance in patients with asymptomatic/minimally symptomatic aortic stenosis and to study its determinants.

Methods and results: One hundred four patients with at least moderate asymptomatic/minimally symptomatic aortic stenosis (median age 79 years, 57% male) underwent 2-dimensional speckle tracking echocardiography and exercise-stress echocardiography with cardiopulmonary exercise test. Results indicated that 73% of patients have effort intolerance defined as %predicted peak V_O2<70%. Left ventricular global longitudinal strain (odds ratio [OR], 3.13, per 3.2% decrease, P<0.01), left atrial reservoir strain (OR, 1.91, per 7.9% decrease, P=0.01), and right ventricular free wall strain (OR, 2.12, per 5.9% decrease, P=0.01) were all associated with effort intolerance. A Strain Index was determined as a sum of points based on receiver operator characteristics analysis: left ventricular global longitudinal strain >17.2%, 15.7% to 17.2%, and <15.7%; left atrial reservoir strain >25.5%, 20.7 to 25.5%, and <20.7%; and right ventricular free wall strain >22.5%, 17.2 to 22.5%, and <17.2%; each variable was associated with 0, 1, and 2 points, respectively. The Strain Index ≥2, the slope of tricuspid annular plane systolic excursion versus systolic pulmonary artery pressure <0.25 mm/mm Hg and the slope of mean pulmonary artery pressure versus cardiac output >4.17 mm Hg/min per L were also significantly associated with effort intolerance. Significantly higher cardiac death and heart failure-related rehospitalization were observed in the effort-intolerance group.

Conclusions: Both aortic stenosis severity and extra-aortic cardiac injuries lead to effort intolerance. Strain Index and exercise indices such as tricuspid annular plane systolic excursion versus systolic pulmonary artery pressure and mean pulmonary artery pressure versus cardiac output slopes may be valuable for risk stratification in minimally symptomatic/asymptomatic aortic stenosis.

Keywords: aortic stenosis; cardiac damage; effort intolerance; exercise‐stress echocardiography; strain.