Why the study?
MitraClip is approved for functional mitral regurgitation but MR recurs in over one third of patients, possibly due to device-induced mechanical effects.
Does simulated MitraClip alter leaflet stress and myocardial strain in models of functional mitral regurgitation?
Does simulated MitraClip alter leaflet stress and myocardial strain in models of functional mitral regurgitation?
Finite element modeling demonstrates that MitraClip increases mitral leaflet stress and radial strain in the LV sub-valvular myocardium, effects that are augmented by LV enlargement, potentially explaining mechanisms of MR recurrence.
Answers are grounded in this paper and cite their sources.
May increase leaflet/subvalvular strain after MitraClip in FMR-CAD; leaves open mechanistic role in recurrent MR and requires clinical validation.
Purpose MitraClip is the sole percutaneous device approved for functional mitral regurgitation (MR; FMR) but MR recurs in over one third of patients. As device-induced mechanical effects are a potential cause for MR recurrence, we tested the hypothesis that MitraClip increases leaflet stress and procedure-related strain in sub-valvular left ventricular (LV) myocardium in FMR associated with coronary disease (FMR-CAD). Methods Simulations were performed using finite element models of the LV + mitral valve based on MRI of 5 sheep with FMR-CAD. Models were modified to have a 20% increase in LV volume (↑LV_VOLUME) and MitraClip was simulated with contracting beam elements (virtual sutures) placed between nodes in the center edge of the anterior (AL) and posterior (PL) mitral leaflets. Effects of MitraClip on leaflet stress in the peri-MitraClip region of AL and PL, septo-lateral annular diameter (SLAD), and procedure-related radial strain ( E rr ) in the sub-valvular myocardium were calculated. Results MitraClip increased peri-MitraClip leaflet stress at end-diastole (ED) by 22.3±7.1 kPa (p<0.0001) in AL and 14.8±1.2 kPa (p<0.0001) in PL. MitraClip decreased SLAD by 6.1±2.2 mm (p<0.0001) and increased E rr in the sub-valvular lateral LV myocardium at ED by 0.09±0.04 (p<0.0001)). Furthermore, MitraClip in ↑LV_VOLUME was associated with persistent effects at ED but also at end-systole where peri-MitraClip leaflet stress was increased in AL by 31.9±14.4 kPa (p=0.0268) and in PL by 22.5±23.7 kPa (p=0.0101). Conclusions MitraClip for FMR-CAD increases mitral leaflet stress and radial strain in LV sub-valvular myocardium. Mechanical effects of MitraClip are augmented by LV enlargement.
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Zhang et al. (2019) studied this question.
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