Normal Ranges of Global Left Ventricular Myocardial Work Indices in Adults: A Meta-Analysis

Recent studies have demonstrated that left ventricular myocardial work (MW) is incremental in diagnosis and prognostication compared with left ventricular ejection fraction and myocardial strain. The authors performed a meta-analysis of normal ranges of noninvasive MW indices including global work index, global constructive work, global wasted work, and global work efficiency and determined confounders that may contribute to variance in reported values.Four databases (PubMed, Scopus, Embase, and the Cochrane Library) were searched through January 2021 using the key terms "myocardial work," "global constructive work," "global wasted work," "global work index," and "global work efficiency." Studies were included if the articles reported LV MW using two-dimensional transthoracic echocardiography in healthy normal subjects, either in a control group or comprising the entire study cohort. The weighted mean was estimated by using the random-effect model with a 95% CI. Heterogeneity across included studies was assessed using the I2 test. Funnel plots and the Egger regression test were used to assess potential publication bias.The search yielded 476 articles. After abstract and full-text screening, we included 13 data sets with 1,665 patients for the meta-analysis. The reported normal mean values of global work index and global constructive work among the studies were 2,010 mm Hg% (95% CI, 1,907-2,113 mm Hg%) and 2,278 mm Hg% (95% CI, 2,186-2,369 mm Hg%), respectively. Mean global wasted work was 80 mm Hg% (95% CI, 73-87 mm Hg%), and mean global work efficiency was 96.0% (95% CI, 96%-96%). Furthermore, gender significantly contributed to variations in normal values of global work index, global wasted work, and global work efficiency. No evidence of significant publication bias was observed.In this meta-analysis, the authors provide echocardiographic reference ranges for noninvasive indices of MW. These normal values could serve as a reference for clinical and research use.