Abstract 13596: Magnetic Resonance - Derived Pre-contrast T1 Relaxation Time is the Accurate Marker of Diffuse Myocardial Fibrosis in Severe Aortic Valve Disease: A Comparison With Left Ventricular Myocardial Biopsy

Abstract

Introduction: Diffuse myocardial fibrosis (DFM) is the major mechanism in the pathophysiology of the aortic stenosis and its complications. DMF is detectable by magnetic resonance imaging (MRI) using the T1 mapping technique. Hypothesis: The MRI derived native T1 relaxation time and myocardial extracellular volume fraction (ECV) will be significantly related to the extent of DMF et targeted myocardial left ventricular (LV) biopsy. Methods: The study population consisted of 40 consecutive patients (age 63±8y, 65% males) undergoing surgery for severe aortic stenosis (77.5%), aortic root dilatation (7.5%) or valve regurgitation (15%). All patients underwent MRI-derived T1 mapping and 2D-, 3D speckle tracking-derived strain analysis prior to surgery. The T1 relaxation time was assessed in basal interventricular septum pre and 10 min post contrast administration using the modified Look-Locker Inversion recovery sequence. A LV myocardial biopsy specimen was obtained during surgery from basal interventricular septum under the guidance of the MRI operator to assure spatial concordance with the MRI assessment. The percentage of myocardial collagen was quantified as a ratio of Picrosirius Red-positive area over total sample area using the Image J. Results: The average percentage of myocardial collagen was 22 ± 14.8 %. The average native T1 relaxation time and ECV was 1010 ± 48 ms and 0.288 ± 0.055, respectively. Both native T1 relaxation time with cutoff value of ≥ 1010 ms (Ss=90%, Sp=73%, AUC =0.82) and ECV with cutoff value of ≥ 0.315 (Ss=80%, Sp=90%, AUC =0.85) showed high accuracy to identify extensive (> 30%) myocardial collagen content (Figure 1A, 1B). The native T1 mapping showed significant correlation with LV mass, 2D and 3D global longitudinal strain (all p<0.05) while the ECV did not (p=NS). Conclusions: Native T1 relaxation time is the accurate marker of diffuse myocardial fibrosis with the significant relationship with LV morphology and myocardial function.