Abstract 663: Comparison of Subendocardial and Subepicardial Radial Strain in Patients With Left Ventricular Hypertrophy Secondary to Aortic Valve Stenosis Before and After Aortic Valve Replacement
Background: Strain imaging has been used to show differences in subendocardial and subepicardial systolic deformation. Transmural left ventricular (LV) wall thickening might be a heterogeneous process, with the endocardial thickening more than the epicardial in normal subjects. Therefore, we conducted a study to evaluate subepicardial and subendocardial strain in patients with LV hypertrophy secondary to aortic valve stenosis (AS) before and after aortic valve replacement.
Methods: We performed echocardiography in 73 consecutive patients with AS who had preserved systolic function (ejection fraction>50%) and no coronary artery disease: 10 with mild AS (area >1.5cm2), 15 with moderate AS (area ≥ 1.0cm2, ≤ 1.5cm2) and 48 with severe AS (area < 1.0cm2). LV mass index, ejection fraction (EF) and midwall fractional shortening (MWFS) were calculated. Subendocardial radial strain (En), subepicardial radial strain (Ep) and transmural radial strain (Tr) were measured in the posterior segment of LV short-axis view by using Velocity Vector Imaging™.
Results: There was no significant difference in EF among groups (Table 1⇓). Although Tr and Ep were not different among groups, En and En to Ep ratio were significantly lower in patients with severe AS. En, Ep and Tr showed no correlation with LV pressure, however, En to Ep ratio showed a significant correlation with LV mass index (R=0.44, P<0.01). In 15 patients who underwent aortic valve replacement, En and En to Ep ratio increased after aortic valve replacement (37.1±8.2 to 47.8±10.6, 1.38±0.18 to 1.88±0.24; P<0.001), whereas Tr, Ep, EF, and MWFS did not change significantly.
Conclusions: En to Ep ratio were significantly reduced in patients with LV hypertrophy secondary to AS and increased after aortic valve replacement. Therefore, the predominance of subendocardial over subepicardial thickening is variable according to myocardial condition, which indicates En to Ep ratio might be a sensitive marker for myocardial function.