Finite-element based optimization of left ventricular passive stiffness in normal volunteers and patients after myocardial infarction: Utility of an inverse deformation gradient calculation of regional diastolic strain

Abstract Introduction Left ventricular (LV) diastolic dysfunction (DD) is common after myocardial infarction (MI). Whereas current clinical assessment of DD relies on indirect markers including LV filling, finite element (FE) -based computational modeling directly measures regional diastolic stiffness. We hypothesized that inverse deformation gradient (DG) method calculation of diastolic strain (IDGDS) allows the FE model-based calculation of regional diastolic stiffness (material parameters; MP) in post-MI patients with DD. Methods Cardiac magnetic resonance (CMR) with tags (CSPAMM) and late gadolinium enhancement (LGE) was performed in 10 patients with post-MI DD and 10 healthy volunteers. The 3-dimensional (3D) LV DG from end diastole to early diastolic filling (EDF; D G E D → E D F ) was calculated from CSPAMM. Diastolic strain was calculated from D G E D F → E D by inverting the D G E D → E D F . FE models were created with MI and non-MI (remote; RM) regions determined by LGE. Guccione MPs C, and exponential fiber, b f , and transverse, b t , terms were optimized with IDGDS strain. Results 3D circumferential and longitudinal diastolic strains ( E c c ; E l l ) calculated using IDGDS in CSPAMM obtained in volunteers and MI patients were E c c H  = 0.27 ± 0.01, E l l H  = 0.24 ± 0.03 and E c c M I  = 0.21 ± 0.02, and E l l M I  = 0.15 ± 0.01, respectively. MPs in the volunteer group were C H  = 0.013 [0.001, 0.235] kPa, b f H  = 20.280 ± 4.994, and b t H  = 7.460 ± 2.171 and C R M  = 0.0105 [0.010, 0.011] kPa, b f R M  = 50.786 ± 13.511 (p = 0.0846), and b t R M  = 17.355 ± 2.743 (p = 0.0271) in the remote myocardium of post-MI patients. Conclusion Diastolic strain, calculated from CSPAMM with IDGDS, enables calculation of FE model-based regional diastolic material parameters. Transverse stiffness of the remote myocardium ( b t R M ) may be a valuable new metric for determination of DD in patients after MI.