Myocardial biopsies and CMR in severe aortic stenosis revealed that collagen volume fraction peaked at the base of the heart (median 19%) and correlated with extracellular volume and LV function.
Cross-Sectional (n=43)
How does the distribution of diffuse myocardial fibrosis assessed by CMR and biopsy correlate with left ventricular function in severe aortic stenosis?
In severe aortic stenosis, diffuse myocardial fibrosis is unevenly distributed, peaking at the base of the heart, and correlates with both CMR extracellular volume and systolic functional parameters.
Background Aortic stenosis (AS) leads to left ventricular (LV) remodelling and fibrosis. Myocardial fibrosis can be focal and irreversible, associated with poor prognosis, or diffuse and potentially reversible after surgery. Cardiac magnetic resonance imaging (CMR) shows promise in quantifying diffuse myocardial fibrosis (DMF), but methods vary in precision. The aim of this study was to investigate the presence and distribution of DMF from myocardial biopsies and CMR tissue characteristics in severe AS. Secondarily, explore the association between DMF and LV function. Methods Forty-three patients with severe AS underwent CMR and transthoracic echocardiography within 1 week before surgical aortic valve replacement. CMR included balanced steady-state free-precession cine images, T1 relaxometry with Modified Look-Locker Inversion recovery and extracellular volume calculations. Endomyocardial biopsies were sampled. Results Histological analysis of 192 biopsies showed a median LV collagen volume fraction (CVF) of 19%, peaking in segment 1, according to the segment model recommended by the American Heart Association (AHA). There were significant moderate correlations between CVF and extracellular volume in AHA segments 1 (r² = 0.54, p<0.01) and 16 (r² = 0.44, p=0.03), where the DMF had the highest prevalence. Functional assessments demonstrated correlations between CVF and global circumferential and radial strain (r 2 0.31, p=0.04 respectively r 2 −0.33, p=0.03), as well as LV ejection fraction (r 2 −0.34, p=0.03). T1 relaxation time correlated with GLS (r 2 0.42, p<0.01), mitral annular plane systolic excursion (r 2 −0.39, p=0.01) and mean S’ LV (r 2 −0.45, p<0.01) from transthoracic echocardiography. Conclusion CVF varied across LV segments and was significantly highest at the base of the heart, suggesting the start location for fibrosis. Systolic functional data correlated with CVF and T1 relaxation time.
Holmberg et al. (Thu,) conducted a cross-sectional in severe aortic stenosis (n=43). Cardiac magnetic resonance imaging and endomyocardial biopsies was evaluated on Presence and distribution of diffuse myocardial fibrosis and its association with left ventricular function. Myocardial biopsies and CMR in severe aortic stenosis revealed that collagen volume fraction peaked at the base of the heart (median 19%) and correlated with extracellular volume and LV function.