Interstitial Fibrosis, Left Ventricular Remodeling, and Myocardial Mechanical Behavior in a Population-Based Multiethnic Cohort

Abstract

Background Tagged cardiac magnetic resonance (CMR) provides detailed information on regional myocardial function and mechanical behavior. T1 mapping by CMR allows non-invasive quantification of myocardial extracellular expansion (ECE) which has been related to interstitial fibrosis in previous clinical and sub-clinical studies. We assessed gender associated differences in the relation of ECE to LV remodeling and myocardial systolic and diastolic deformation in a large community based multi-ethnic population. Methods and Results Mid-ventricular mid-wall peak circumferential shortening and early diastolic strain rate (EDSR); LV torsion and torsional recoil rate were determined using CMR tagging. Mid ventricular short axis T1 maps were acquired in the same examination pre and post-contrast injection using Modified Look-Locker Inversion Recovery sequence (MOLLI). Multivariable linear regression (B= estimated regression coefficient) was used to adjust for risk factors and sub-clinical disease measures. Of 1230 participants, 114 participants had visible myocardial scar by late gadolinium enhancement. Participants without visible myocardial scar (n=1116) had no previous history of clinical events. In the latter group, multivariable linear regression demonstrated that lower post-contrast T1 times, reflecting greater ECE were associated with lower circumferential shortening (B=−0.1, p=0.0001), lower end diastolic volume index (LVEDVi) (B=0.6, p=0.0001) and lower LV end diastolic mass index (LVMi) (B=0.4, p=0.0001). In addition, lower post-contrast T1 times were associated with lower EDSR (B=0.01, p=0.03) in women only; and lower LV torsion (B=0.005, p=0.03) a lower LV ejection fraction (B=0.2, p=0.01) in men only. Conclusions Greater ECE is associated with reduced LVEDVi and LVMi in a large multi-ethnic population without history of previous cardiovascular events. In addition, greater ECE is associated with reduced circumferential shortening, lower EDSR, and a preserved ejection fraction in women; while in men, greater ECE is associated with greater LV dysfunction manifested as reduced circumferential shortening, reduced LV Torsion and reduced ejection fraction.

Electrocardiographic Impact of Myocardial Diffuse Fibrosis and Scar: MESA (Multi-Ethnic Study of Atherosclerosis)

“…Although recent studies reported that lower postcontrast T1 times were associated with lower LV EDV and LV mass (22,23), we found that diffuse fibrosis was related to lower QRS amplitude independent of both LV EDV and mass. Therefore, the QRS amplitude can be even lower in the setting of increased diffuse fibrosis and decreased LV volume and mass according to myocyte loss.…”

“…The MESA cardiac MR imaging protocol and image analysis have been previously described in detail (22,23). Briefly, cardiac MR images were obtained by using 1.5-T imaging units (Avanto and …”

Hypertrabeculated Left Ventricular Myocardium in Relationship to Myocardial Function and Fibrosis: The Multi-Ethnic Study of Atherosclerosis

“…Cardiac MR examinations were performed at the six MESA field centers with 1.5-T MR imagers, as described previously (18,19). In brief, electrocardiographically gated long-and short-axis cine images were acquired by using a steady-state free precession sequence (repetition time msec/echo time msec, 2.2/1.1; temporal resolution, 40 msec; Table 1 shows the population characteristics, traditional cardiovascular risk factors, and mean 6 standard deviation deviation, and categorical variables are given as frequencies and percentages.…”

Celastrol-Induced Suppression of the MiR-21/ERK Signalling Pathway Attenuates Cardiac Fibrosis and Dysfunction

“…In myocardial fibrosis, excessive collagen deposition and extracellular matrix (ECM) accumulation result in myocardial remodelling, cardiac dysfunction and arrhythmias [1][2][3]. However, therapeutic strategies for preventing fibrosis remain limited.…”