1349083 - Global Longitudinal Strain Provides a Composite Measure of Left Ventricular Function and Myocardial Fibrosis in Heart Failure: A Cardiac MRI Study

Background: Global longitudinal strain (GLS) provides a measure of left ventricular longitudinal systolic function and correlates with left ventricular ejection fraction (LVEF). GLS is known to also correlate with markers of myocardial fibrosis in aortic stenosis, however this relationship has not been established in a heart failure population. This study aimed to assess the prognostic value of GLS in an observational heart failure cohort, and to determine the relationship between GLS and cardiovascular magnetic resonance (CMR) markers of left ventricular function and myocardial fibrosis.

Methods: In this prospective, observational study, patients (n=324) with heart failure from six tertiary cardiac centres in Singapore underwent CMR at 3T (Ingenia, Philips Healthcare, The Netherlands) and plasma biomarker sampling.  LVEF was measured from a short axis cine stack. GLS was measured using feature tracking (CVI42, Circle Cardiovascular Imaging, Calgary, Canada). Pre- and post-contrast T1 mapping was performed with modified Look-Locker Inversion-recovery (MOLLI) 5s(3s)3s and 4s(1s)3s(1s)2s acquisition schemes, respectively, to derive the extracellular volume fraction (ECV) and the total extracellular volume of the left ventricular myocardium indexed to body surface area (iECV).  Late gadolinium enhancement (LGE) imaging was performed to assess for focal replacement fibrosis. The primary outcome was a composite of all-cause mortality or heart failure hospitalisation.

Results: The primary outcome occurred in 70 patients over a median [interquartile range] of 730 [716-734] days follow-up. In univariable Cox regression models, left ventricular end diastolic volume index (LVEDVi), left ventricular mass index (LVMi), LVEF, GLS, native T1, ECV, iECV, and presence of LGE were associated with the primary outcome. In multivariable Cox regression models, only GLS remained as a CMR predictor of outcomes (hazard ratio 1.15 [1.07-1.23], p< 0.001, Table 1). The addition of GLS to a model containing clinical parameters, N-terminal pro-brain natriuretic peptide (NT-proBNP), LVEF, presence of LGE, and iECV resulted in incremental prognostic performance (chi-squared 46 vs 40, p=0.005). In a multivariable linear regression model using only CMR covariates, LVEF, native T1, iECV, and presence of LGE were all associated with GLS (global R²=0.63, p< 0.001, Table 2). Combining the strongest clinical and imaging predictors, below median |GLS| < 9.9% and presence of diabetes mellitus had the strongest association with outcomes (log rank 37, p< 0.001, Figure 1).

Conclusion: In patients with heart failure, GLS is a strong predictor of outcomes. GLS shows strong correlation with left ventricular function (LVEF) and moderate correlation with CMR markers of fibrosis. GLS provides incremental prognostic value to LVEF and CMR markers of fibrosis in this cohort. Taken together, GLS appears to be a composite marker of left ventricular function and myocardial fibrosis in heart failure.