Abstract 18855: Global Longitudinal Strain is Reduced in Congenital Aortic Stenosis and Associated With Focal Myocardial Fibrosis
Background: In congenital aortic stenosis (AS), therapy to relieve obstruction is directed toward preserving myocardial function and structure, but the optimal timing remains controversial. Myocardial strain measurements of regional systolic function may be more sensitive than conventional measures, such as ejection fraction (EF), and thus serve to refine the indications for intervention. We hypothesized that congenital AS pts with normal EF have impaired LV strain associated with myocardial fibrosis.
Methods: Inclusion criteria for cases were congenital AS with a peak Doppler gradient ≥20 mm Hg at any time, age<30 yo, extracellular volume fraction (ECV) and late gadolinium enhancement (LGE) assessed by cardiac MR (CMR), LV EF >54%, and a concurrent echocardiogram. Strain measures were compared to normal controls of similar age (n=15, median age 15). Speckle tracking echocardiographic strain was used to measure peak global longitudinal, circumferential, and radial strain. The ECV, a measure of diffuse fibrosis, was calculated with a Look-Locker technique. LGE was used to assess focal fibrosis, and classified as present or absent.
Results: Twenty-nine pts met inclusion criteria with a median age of 16 yrs (1.7-25), peak AS gradient of 48 mm Hg (0-90), aortic regurgitation fraction by CMR of 25% (0-60), LV EF 65% (55-79), and mean ECV 0.27 (0.22-0.38). Global longitudinal strain was significantly lower in AS patients than controls (-17.0 ± 3.0% vs. -20.9 ± 2.4%, p<0.001). Global circumferential strain (-26.7 ± 5.6% vs. -25.9 ± 3.6%, p=0.72) and global radial strain (29.6 ± 7.7% vs. 34.2 ± 8.8%, p=0.063) were not significantly different. Reduced global longitudinal strain was associated with LGE (p=0.036) but not ECV (p=0.14) Global longitudinal strain was not associated with peak echo AS gradient prior to CMR, LV mass/volume ratio, or a history of any aortic valve intervention.
Conclusions: In this cohort of children and young adults with congenital AS and preserved EF, global longitudinal strain was lower than in controls and associated with focal fibrosis but not diffuse fibrosis. Further studies are warranted to determine whether strain measurements should be used to determine the timing for intervention in AS to better preserve myocardial structure.
- © 2013 by American Heart Association, Inc.