Prognostic impact of left ventricular myocardial work in patients undergoing surgery for primary mitral regurgitation

Abstract Background Although left ventricular ejection fraction (LVEF) is widely used as a parameter for the assessment of LV systolic function, LVEF can overestimate LV systolic function in patients with severe mitral regurgitation (MR) due to its high load-dependency. Echocardiography-based, left ventricular myocardial work (LVMW) can assess LV function by incorporating LV afterload. Purpose This study aims to evaluate the prognostic value of LVMW indices in patients with primary MR undergoing mitral valve surgery. Methods Individuals who underwent mitral valve surgery for severe primary MR were included. All patients underwent transthoracic echocardiography before surgery. LVMW was derived from a vendor-specific package which integrates LV global longitudinal strain with sphygmomanometric blood pressure to construct pressure-strain loops during the cardiac cycle. (Figure 1) For the LVMW indices, previously-established normal values were used as thresholds. The primary endpoint was all-cause mortality after mitral valve surgery. Results A total of 309 patients (mean age 63 ± 12 years, 68% male) with severe, primary MR who underwent surgery, were included. The mean LV global work index (LVGWI) was 1977 ± 537 mmHg% and 132 (43%) patients had impaired LVGWI (≤ 1900 mmHg%). During a median follow-up of 5.0 years (interquartile range, 2.5-8.9), 27 (8.7%) patients died after mitral valve surgery. Patients with impaired LVGWI or LV GLS (≤ 20%) had lower survival rates compared to the group with preserved LVGWI (p <0.01) or LVGLS (p = 0.02), whereas there was no significant difference in the survival rate between patients with LVEF ≤ 60% and > 60%. (Figure 2) Furthermore, LVGWI ≤ 1900 mmHg% demonstrated incremental prognostic value over LVGLS (p = 0.049) for all-cause mortality. Conclusions In patients with severe, primary MR who underwent surgery, impaired pre-operative LVGWI was associated with a higher mortality risk. In addition, impaired LVGWI had incremental prognostic value over LVGLS. Based on these findings, LVMW is a promising parameter for predicting postoperative outcome and determining the optimal timing of valve surgery in patients with severe, primary MR.Fig1.Echo-derived Myocardial workFig2.Kaplan-Meier curves