Left-Ventricular Reference Myocardial Strain Assessed by Cardiovascular Magnetic Resonance Feature Tracking and fSENC-Impact of Temporal Resolution and Cardiac Muscle Mass.

ABSTRACT

Aims: Cardiac strain parameters are increasingly measured to overcome shortcomings of ejection fraction. For broad clinical use, this study provides reference values for the two strain assessment methods feature tracking (FT) and fast strain-encoded (fSENC) cardiovascular magnetic resonance (CMR) imaging, including the child/adolescent group and systematically evaluates the influence of temporal resolution and muscle mass on strain. Methods and Results: Global longitudinal (GLS), circumferential (GCS), and radial (GRS) strain values in 181 participants (54% women, 11-70 years) without cardiac illness were assessed with FT (CVI42® software). GLS and GCS were also analyzed using fSENC (MyoStrain® software) in a subgroup of 84 participants (60% women). Fourteen patients suffering hypertrophic cardiomyopathy (HCM) were examined with both techniques. CMR examinations were done on a 3.0T MR-system. FT-GLS, FT-GCS, and FT-GRS were -16.9 ± 1.8%, -19.2 ± 2.1% and 34.2 ± 6.1%. fSENC-GLS was higher at -20.3 ± 1.8% (p < 0.001). fSENC-GCS was comparable at-19.7 ± 1.8% (p = 0.06). All values were lower in men (p < 0.001). Cardiac muscle mass correlated (p < 0.001) with FT-GLS (r = 0.433), FT-GCS (r = 0.483) as well as FT-GRS (r = -0.464) and acts as partial mediator for sex differences. FT-GCS, FT-GRS and fSENC-GLS correlated weakly with age. FT strain values were significantly lower at lower cine temporal resolutions, represented by heart rates (r = -0.301, -0.379, 0.385) and 28 or 45 cardiac phases per cardiac cycle (0.3-1.9% differences). All values were lower in HCM patients than in matched controls (p < 0.01). Cut-off values were -15.0% (FT-GLS), -19.3% (FT-GCS), 32.7% (FT-GRS), -17.2% (fSENC-GLS), and -17.7% (fSENC-GCS). Conclusion: The analysis of reference values highlights the influence of gender, temporal resolution, cardiac muscle mass and age on myocardial strain values.