Abstract 12605: Defining the Reference Range for Left Ventricular Strain by Echocardiography in Healthy Subjects: A Novel Meta-analysis Strategy

Background: Left ventricular global longitudinal strain (LVGLS), circumferential strain (LVGCS) and radial strain (LVGRS) are established echocardiographic parameters of systolic function with wide clinical applicability and prognostic implications. Despite this, the reference ranges of left ventricular (LV) strain, particularly the lower limit of normal (LLN), are not well established. This meta-analysis aims to determine the mean and LLN of two- (2D) and three-dimensional (3D) LV strain in healthy subjects and factors that may influence strain measurements. Methods: We searched Pubmed, Embase and Cochrane databases until 30 November 2019 for studies reporting left ventricular (LV) global strain in at least 50 healthy subjects. We pooled the mean and LLN of 2D and 3D LV strain using random-effects models, and performed subgroup and meta-regression analysis for 2D-LVGLS. Results: Forty-four studies were eligible totaling 8747 subjects. The pooled means and LLNs (95% confidence intervals) were -20.0% (-20.6%, -19.5%) and -15.6% (-16.2%, -15.0%) respectively for 2D-LVGLS; -22.1% (-23.7%, -20.5%) and -15.7% (-17.3%, -14.1%) respectively for 2D-LVGCS; and 48.0% (43.8%, 52.1%) and 23.2% (20.9%, 25.5%) respectively for 2D-LVGRS; all listed in Table 1. Significant heterogeneity was observed for almost all pooled LV strain analyses. The only factors associated with significant differences in both pooled mean and LLN of 2D-LVGLS were systolic blood pressure and vendor software. Conclusion: Pooled means and LLNs of 2D- and 3D- LV global strain parameters in healthy subjects were reported. Based on the pooled LLNs and their confidence intervals, the thresholds for abnormal, borderline and normal LV strains can be defined. Systolic blood pressure and vendor software were the most important parameters influencing 2D-LVGLS mean and LLN. Our novel methodology can also be applied to the meta-analysis of other echocardiographic parameters to define reference ranges.