Myocardial fibrosis is associated with worse left ventricular strain and synchrony assessed by novel CMR imaging in the general population: data from the Akershus Cardiac examination 1950 study

Investigate the relationship between myocardial fibrosis and left ventricular (LV) deformation and mechanical synchrony using state-of-the-art cardiac magnetic resonance imaging (CMR) in an elderly general population. In 200 participants without known coronary artery disease, all born in 1950, diffuse fibrosis was quantified by septal extracellular volume (ECV) fraction and focal fibrosis by late gadolinium enhancement (LGE). LV global longitudinal and circumferential strain (GLS, GCS) and mechanical dispersion (MD) were derived by CMR-feature tracking (CMR-FT). Myocardial deformation was also assessed using fast strain-encoded MR (fSENC) percentage of LV segments with normal longitudinal and circumferential strain (≤ -17%). The associations between myocardial fibrosis and bothstrain and mechanical dispersion were examined using regression analyses. Median age was 69.0 (interquartile range (IQR) 68.6-69.3) years and 52% were male. In adjusted models, LGE presence and volume were associated with worse GLS (presence: β = 0.83, 95% CI 0.02 to 1.63; volume: β = 0.17, 95% CI 0.04 to 0.30) and lower fSENC % normal myocardium (presence: β = -6.68, 95% CI -13.33 to -0.04; volume: β = -1.66, 95% CI -3.14 to -0.18). The association between LGE (presence and volume) and GCS was attenuated when adjusting for indexed LV end diastolic volume. ECV values above 26% were associated with worse GLS, GCS and lower fSENC % normal myocardium. Participants with focal scars had significantly higher median MD (89.0 ms (IQR 71.2, 121.1) vs 78.0 ms (IQR 60.4, 97.3)), and focal scars were associated with MD above the sex specific upper quartile (OR 2.64, 95% CI (1.18, 5.94) for LGE presence and 1.22, 95% CI (1.05, 1.42) for LGE volume). In this elderly general population, focal myocardial fibrosis was associated with worse LV deformation and synchrony. There was a threshold effect with a non-linear association between diffuse fibrosis and strain.