Non­invasive myocardial work indices in patients undergoing mitraclip implantation

Background: Percutaneous MitraClip Implantation is a promising alternative treatment for patients with severe mitral regurgitation (sMR). Myocardial Work (MW) is an interesting non­invasive parameter to evaluate cardiac performance, as a result of left ventricle (LV) pressure­strain loops. Purpose: The present study sought to evaluate the impact of MitraClip Implantation on MW indices. Methods: The study population consisted of 20 consecutive patients (mean age 74 ±6 years) with functional sMR, LV systolic dysfunction and advanced NYHA class, all successfully treated with MitraClip Implantation. Global Work Index (GWI), Global Constructive Work (GCW), Global Work Waste (GWW) and Global Work Efficiency (GWE) were estimated by LV pressure­strain loops using custom software, before and at 1­month after MitraClip Implantation. MR grade, LV end­diastolic and end­systolic volumes, indexed to body surface area (EDVi and ESVi, respectively), ejection fraction (EF), stroke volume index (SVi), systolic pulmonary artery pressure (SPAP), global longitudinal strain (GLS) were also evaluated by 2D transthoracic echocardiography. Patients’ functional status, by means of six minute walking test (6­MWT), NYHA class, and EuroQOL scale were also evaluated at 1­month follow­up. Results: A significant reduction of MR (from 3.8 ± 0.3 to 1.3 ± 0.4; p = 0.001) was obtained in the overall population at follow­up. There was not a significant difference in EDV (105.9±28.5 ml/m2 vs. 113.5±32.6 ml/m2), ESV (75.6±21 ml/m2 vs. 79.4±25.1 ml/m2), EF (31.3±13% vs 30.8±12.3%), SVi (31.5±8 ml/m2 vs. 37.6±9.9 ml/m2), GLS (­8.2±3.3% vs. ­8.6±2.1%) and SPAP (56.2±28.7mmHg vs. 46.2± 11.7 mmHg) (p=NS for all). Conversely, a significant increase in GWI (608.1±375.1 mmHg% vs. 812.4±321.4 mmHg%, p=0.002), in GCW (771.8±392.2 mmHg% vs. 998.8±332.5 mmHg%, p= 0.007, Figure) and in GWW (145.9±79.6 mmHg% vs. 188±85.1 mmHg%, p =0.048) was observed, while there was no significant difference for GWE (78.8±12.4% vs. 79.1±8.5%, p=0.8). NYHA class (from 2.67 ± 0.78 to 2.09 ± 0.59 p = 0.038) significantly reduced and 6­MWT (from 273.5 ± 103.7 m to 298.1 ± 104.6 m, p 0.032) improved, while no significant difference was found for EuroQOL (69 ± 17.9 to 69.8 ± 15.4, p= 0.8). Conclusion: Myocardial performance as assessed by myocardial work significantly improves 1­month after MitraClip Implantation. Our preliminary data need to be confirmed in a larger population and with a longer follow­up.