Transapical Ventricular Reshaping Reduces Functional Mitral Regurgitation and Improves Ventricular Function in a Preclinical Model of Ischemic Cardiomyopathy.

OBJECTIVE: Significant proportion of patients with advanced heart failure presents with dilated left ventricles (LVs) and functional mitral regurgitation (FMR). These patients currently have limited treatment options. MitraClip has benefited patients only with a smaller LVs (End-diastolic dimension<70mm), whereas those with larger LVs did not benefit. A possible explanation is correcting FMR alone may not adequately reduce the wall stresses of a dilated LV. We have developed a beating heart device that approximates the papillary muscles to reduce FMR, but also modifies the LV size and shape to reduce wall stress.

METHODS: Yorkshire swine (n=16) had a myocardial infarction (MI) by permanent occlusion of the left circumflex with intracoronary ethanol. Three months later, the animals developed heart failure and moderate or greater FMR. Through a transapical approach, the new device was implanted under echo guidance to reshape the LV and correct FMR. The acute impact of this approach on the mitral valve (MV) and LV was assessed with echocardiography and invasive hemodynamics.

RESULTS: After reshaping, echocardiography showed a decrease in end-diastolic volume (EDV) by 36.3±30.5 ml (p<0.001), a decrease in sphericity index by 0.143±0.087 (p<0.001), and an increase in ejection fraction of 5.90±6.38% (p<0.01). Mitral valve tenting area was reduced by 39.29±33.66 mm2 (p<0.001), coaptation length was increased by 2.12±1.02 mm (p<0.001), and posterior excursion angle was improved by 9.07±9.14° (p<0.01), resulting in FMR reduction.

CONCLUSIONS: Correction of FMR with favorable changes in mitral valve geometry, along with reduction in LV geometry are possible with the proposed device.