Relationship between myocardial energy expenditure and postoperative ejection fraction in patients with severe mitral regurgitation

Abstract

Objective: This prospective study aimed to investigate the myocardial energy metabolism in severe mitral regurgitation (MR) and explore its effect on postoperative differentiation of ejection fraction (EF).

Methods: A total of 85 patients with severe MR were prospectively enrolled from October 2018 to June 2019. During the study period, a total of 50 patients underwent mitral valve surgery and 49 patients were finally enrolled due to 1 missing data. Left ventricular function, circumferential end-systolic stress (cESS), and myocardial energy expenditure (MEE) were measured by transthoracic echocardiography preoperatively and 3 months after surgery. Patients were divided into 2 groups according to absolute difference of postoperative differentiation of EF.

Results: Nine patients underwent mitral valve repair and 40 underwent prosthetic valve replacement. Patients with reduced EF had higher MEE demonstrated with cESS and MEE. Negative correlation between preoperative EF and N-terminal pro-brain natriuretic peptide (NT-proBNP), cESS, MEEs, and MEEm and positive correlation between preoperative EF and effective regurgitant orifice area were found. Complications occurred in 12 patients during hospitalization. Basal NT-proBNP, left atrium (LA), and cESS were significantly higher in postoperatively decreased EF group. Taking into consideration the covariates of multiple logistic regression analysis, LA and cESS were found to be independent predictors of EF reduction postoperatively.

Conclusion: Higher LA and cESS are independent predictors of postoperative EF reduction. Preoperative high end-systolic stress could predict postoperative EF reduction and hence could be helpful for determining the timing of mitral valve surgery. Although MEE was higher in postoperatively decreased EF group, it did not reach statistical significance.

Figure 1

(a) Parasternal long-axis view of transthoracic echocardiography. MEE can be calculated by the formula explained in the text. PWT (marked with asterisk), LV diameters, ejection time, LVOT diameter, LVOT, and VTI are needed for the calculation. (b) Ejection time and LVOT VTI (pulsed Doppler of left ventricular outflow track and trace of velocity time integral) are shown LV - left ventricle; LVOT - left ventricular outflow tract; MEE - myocardial energy expenditure; PWT - posterior wall thickness; VTI - velocity time integral