Non-invasive measurement of global myocardial work to predict all-cause death and heart failure hospitalization in non-ischemic cardiomyopathy

Abstract Background Global myocardial work (GMW) can be non-invasively calculated using a dedicated software using global longitudinal strain (GLS) and blood pressure. The prognostic value of GMW in patients with non-ischemic cardiomyopathy (NICM) has not yet been demonstrated. Purpose To stablish the prognostic significance of GMW in NICM. Methods Patients with NICM with an available echocardiogram between 2015 and 2019 and left ventricular ejection fraction (LVEF) <50% were retrospectively included. A dedicated software was used to analyze GMW, global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE). All quantitative variables were modelled as a spline with three knots to account for non-linear associations. Patients were followed up until the occurrence of death, heart failure hospitalization or lost to follow-up. The primary endpoint was a composite of all-cause death of heart failure hospitalization (HFH). Results A total of 524 patients with NICM in whom GMW analysis was feasible were included in the study. Median LVEF was 35 (IQR 27 – 42), and median GMW was 968 (IQR 670 – 1282). There were no significant differences in clinical characteristics between patients with GMW above or below median, except for higher rates of HFH during the previous year in patients with lower GMW. Patients with lower GMW displayed lower LVEF, greater LV dilatation, worse GLS, lower TAPSE and a higher E/e’ ratio (Table 1). GMW and GCW were significantly collinear with GLS (Pearson’s r = -0.85 and -0.83 respectively, p<0.001), GWE was moderately collinear (Pearson’s r = -0.64, p<0.001) whereas GWW was not (Pearson’s r = 0.05, p = 0.23). During a median follow-up of 4.8 years, 164 (31.3%) patients presented the primary endpoint. After adjusting for age, LVEF, end-diastolic volume and TAPSE, GMW showed a significant, non-linear association with the primary endpoint (Figure 1), at the expense of both death and HFH when separately analyzed. Risk progressively increased with a GMW below 2500 mmHg% and plateaued at 1000 mmHg%. Only GCW retained an association with the primary outcome like the one observed with GMW, whereas GWW and GWE did not. Adding GMW to the model led to an improved risk discrimination (AUC increased from 0.66 to 0.69, p = 0.043). Conclusions Global myocardial work and GCW are new independent echocardiographic predictors of all-cause death and HFH in NICM, with higher rates of the outcome at lower GMW and GCW values, whereas GWW and GWE were not associated with event rates in NICM.