Abstract 11168: The Relationship Between Interstitial Fibrosis by T1 Mapping and Regional Myocardial Function by Tagging: The MESA Study

Abstract

Background: T1 mapping allows non-invasive quantification of interstitial fibrosis. Tagged CMR provides reliable information on regional myocardial function. The association between fibrosis and regional function was determined previously in a subset of population with structural cardiac abnormalities. We assessed the relation between fibrosis and regional function in multi-ethnic population.

Methods: 1231 participants (51.4% men), mean age 67±8yrs, had gadolinium enhanced CMR and tagging. Mid-ventricular mid-wall peak circumferential shortening (Ecc) and global torsion were determined using HARP. Ecc is a negative number and more negative values indicate greater circumferential shortening. Mid ventricular short axis T1 maps were acquired pre and post contrast injection using MOLLI. Partition coefficient (Par Coeff) was determined by plotting 1/T1 times of myocardium against blood pool and calculating the slope of resultant linear regression line. Extra cellular volume fraction (ECV) was calculated by ECV= Par Coeff*(1-hematocrit/100). Multivariable linear regression was used to adjust for covariates including age, gender, race and LV mass index (LVMi=LV mass/ BSA).

Results: 39 participants (3.2%) had visible scar on T1 mapping images. ECV and Par Coeff were associated with Ecc (p <0.01) with more shortening in subjects without scar and vice versa in subjects with visible scar. Multivariable linear regression showed that ECV and Par Coeff were associated with greater circumferential shortening. Similar association was seen between increased fibrosis and torsion. This relation remained significant for Par Coeff but not for ECV after adjusting for covariates.

Conclusion: Increased myocardial fibrosis is associated with decreased shortening and torsion in MESA participants with visible scar. However, among those without visible scar increased fibrosis is related to increased shortening, torsion and LVMi suggesting compensatory remodeling.