Native T1 Relaxation Time and Extracellular Volume Fraction as Accurate Markers of Diffuse Myocardial Fibrosis in Heart Valve Disease　– Comparison With Targeted Left Ventricular Myocardial Biopsy –

Abstract

Background:The aim of our study was to investigate the relationship between the cardiac magnetic resonance (CMR)-derived native T1 relaxation time and myocardial extracellular volume (ECV) fraction and the extent of diffuse myocardial fibrosis (DMF) on targeted myocardial left ventricular (LV) biopsy. Methods and Results:The study population consisted of 40 patients (age 63±8 years, 65% male) undergoing valve and/or ascending aorta surgery for severe aortic stenosis (77.5%), root dilatation (7.5%) or valve regurgitation (15%). The T1 relaxation time was assessed in the basal interventricular septum pre-and 10-min post-contrast administration using the modified Look-Locker Inversion recovery sequence prior to surgery. LV myocardial biopsy specimen was obtained during surgery from the basal interventricular septal segment matched with the T1 mapping assessment. The percentage of myocardial collagen was quantified using picrosirius red staining. The average percentage of myocardial collagen was 22.0±14.8%. Both native T1 relaxation time with cutoff value ≥1,010 ms (sensitivity=90%, specificity=73%, area under the curve=0.82) and ECV with cutoff value ≥0.32 (sensitivity=80%, specificity=90%, area under the curve=0.85) showed high accuracy to identify severe (>30%) DMF. The native T1 relaxation time showed significant correlation with LV mass (P<0.01).Conclusions: Native T1 relaxation time and ECV at 10 min after contrast administration are accurate markers of DMF. (Circ J 2016; 80: 1202 -1209

Imaging of Myocardial Fibrosis and Its Functional Correlates in Aortic Stenosis: A Review and Clinical Potential

“…However, FMF develops later in the disease course and, therefore, CMR-derived LGE is not sensitive enough to detect the early stage of myocardial damage. Accordingly, in our previous studies which used CMR-derived T1 mapping (CMR-T1), a total of 25% of patients had extensive (> 30%) DMF and a focal scar was not observed in any of them [23, 24]. Using the MOLLI sequence, CMR-T1 was in fact recently shown to allow accurate detection and quantification of DMF with excellent precision, reproducibility, and scan-rescan stability [22].…”

“…Both native T1 relaxation time and ECV have been significantly associated with DMF at myocardial histology [25-27]. We recently reported the high accuracy of both native T1 relaxation time with a cut-off value ≥1,010 ms (Ss = 90%, Sp = 73%, AUC = 0.82) and ECV with a cut-off value ≥0.315 (Ss = 80%, Sp = 90%, AUC = 0.85) to identify extensive (> 30%) DMF at histology [24]. Moreover, correlations between both native T1 and ECV with prognostic markers such as NT-pro-BNP or troponin have been reported [28, 29].…”

“…First of all, GLS was found to be related to biomarkers of myocardial fibrosis such as those expressing calcification, collagen formation, or breakdown and inflammation [42, 43]. Several studies have also reported significant associations between LV systolic function and both FMF and DMF at CMR or myocardial histology [3, 14, 15, 18, 19, 24, 29, 44-46] (Table 2). Former studies have investigated the relationship between FMF and LV contractile function [14, 44, 45].…”

“…A GLS ≤−11.6% showed a sensitivity of 65% and a specificity of 75% to predict significant FMF (LGE > 10%) [43]. The majority of studies dealing with this issue have focused on DMF [15, 19, 24, 46, 47]. Of the conventional echocardiography-derived parameters, DMF seems to show a significant, though weak, correlation only with LV mass and the LV mass index [23, 24].…”

The Prognostic Role of T1 Mapping Sequences: Can T1 Mapping Parameters Have a Role in Risk Stratification?

“…So CMR-T1 mapping can guide selection of TAVR-valve type, which results in less conduction system compromise in cases with a high risk of conduction disturbance. In addition, elderly persons and those with chronic kidney disease are very common in cases with severe aortic stenosis, so native T1 without contrast could provide helpful information without the use of gadolinium contrast media [57,58]. Chin et al [59] used total extracellular volume indexed by body surface area (iECV) was together with LGE to categorize patients with normal myocardium (iECV<22.5 mL/m 2 ; 51% of patients), extracellular expansion (iECV≥22.5 mL/m 2 ; 22%), and replacement fibrosis (presence of mid-wall LGE, 27%).…”