Normal Ranges of Right Ventricular Systolic and Diastolic Strain Measures in Children: A Systematic Review and Meta-Analysis

Background Establishment of the range of normal values and associated variations of two-dimensional (2D) speckle-tracking echocardiography (STE)–derived right ventricular (RV) strain is a prerequisite for its routine clinical application in children. The objectives of this study were to perform a meta-analysis of normal ranges of RV longitudinal strain measurements derived by 2D STE in children and to identify confounders that may contribute to differences in reported measures. Methods A systematic review was conducted in PubMed, Embase, Scopus, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov . Search hedges were created to cover the concepts of pediatrics, STE, and the right heart ventricle. Two investigators independently identified and included studies if they reported the 2D STE–derived RV strain measure RV peak global longitudinal strain, peak global longitudinal systolic strain rate, peak global longitudinal early diastolic strain rate, peak global longitudinal late diastolic strain rate, or segmental longitudinal strain at the apical, middle, and basal ventricular levels in healthy children. Quality and reporting of the studies were assessed. The weighted mean was estimated using random effects with 95% confidence intervals (CIs), heterogeneity was assessed using Cochran's Q statistic and the inconsistency index ( I2 ), and publication bias was evaluated using funnel plots and Egger's test. Effects of demographic, clinical, equipment, and software variables were assessed in a metaregression. Results The search identified 226 children from 10 studies. The reported normal mean values of peak global longitudinal strain among the studies varied from −20.80% to −34.10% (mean, −29.03%; 95% CI, −31.52% to −26.54%), peak global longitudinal systolic strain rate varied from −1.30 to −2.40 sec−1 (mean, −1.88 sec−1 ; 95% CI, −2.10 to −1.59 sec−1 ), peak global longitudinal early diastolic strain rate ranged from 1.7 to 2.69 sec−1 (mean, 2.34 sec−1 ; 95% CI, 2.00 to 2.67 sec−1 ), and peak global longitudinal late diastolic strain rate ranged from 1.00 to 1.30 sec−1 (mean, 1.18 sec−1 ; 95% CI, 1.04 to 1.33 sec−1 ). A significant base-to-apex segmental strain gradient ( P < .05) was observed in the RV free wall. There was significant between-study heterogeneity and inconsistency ( I2 > 88% and P < .01 for each strain measure), which was not explained by age, gender, body surface area, heart rate, frame rate, tissue-tracking methodology,