Association between aortic stenosis severity and contractile reserve measured by two-dimensional strain under low-dose dobutamine testing

Abstract

Early detection of left ventricle (LV) systolic dysfunction could be a clue for surgical treatment in patients with significant aortic stenosis (AS). Therefore, we evaluated LV peak of global longitudinal strain (PGLS) using speckle tracking imaging at rest and during low-dose dobutamine infusion in asymptomatic patients with moderate and severe AS and preserved LV ejection fraction (EF). All the patients underwent coronary angiography and had no obstructive coronary disease (defined as having no stenosis greater than 50% in diameter). The patients were divided into two groups: above and below median of 0.785 cm2 aortic valve area (AVA). PGLS was measured from acquired apical 4-chamber and 2-chamber cine loops using a EchoPac PC-workstation at rest and during 5 microg/kg/min, 10 microg/kg/min, and 20 microg/kg/min dobutamine infusion, respectively. The global strain was the average of segment strains from the apical views. A total of 62 patients with moderate and severe AS (AVA < = 1.5 cm2), the mean age 66.12 +/- 9.91, (57.14% males), were enrolled in this prospective study. At rest, mean gradient was 43.57 +/- 0.29 mmHg and mean EF was 72.24 +/- 0.45%. When divided according to median AVA, both groups had decreased average PGLS at rest (-9.33 +/- 4.46% vs -8.95 +/- 3.08%; p = ns). During dobutamine both groups increased their average PGLS, but only the group with AVA > median reached the statistical significance (- 8.71 +/- 2.68% vs -11.93 +/- 3.74%, p = 0.002). In addition, PGLS increase was also significant in 4-chamber view in the patients with AVA above median, but only when comparing baseline to peak 20 microg/kg/min (-10.72 +/- 3.07% vs -13.14 +/- 4.79%; p = 0.034). Conversely, in both groups the increase of PGLS in 2-chamber view did not reach significance. Two-dimensional strain speckle tracking analysis of myocardial deformation with measurement of peak systolic strain during dobutamine infusion is a feasible and accurate method to determine myocardial longitudinal systolic function and contractile reserve and may contribute to clinical decision making in patients with significant AS.