What does this research mean for the field?

In healthy subjects, the pooled lower limit of normal for two-dimensional right ventricular global longitudinal strain is -16.4%, establishing a reference threshold for abnormal strain. Novelty: ClaimNovelty.SYNTHESIS. Consensus alignment: ConsensusAlignment.NEUTRAL.

August 20, 2021Open Access

Defining the reference range for right ventricular systolic strain by echocardiography in healthy subjects: A meta-analysis

Q: What is the clinical evidence from this study?

Study design: Meta-Analysis. Population: Healthy subjects (n=4439). Intervention: Two-dimensional right ventricular global longitudinal strain (2D-RVGLS) measurement. Primary outcome: Pooled lower limit of normal (LLN) for 2D-RVGLS (95% CI -17.3%, -15.5%).

TWTom Kai Ming WangCardiac Imaging RGRichard A. GrimmCardiac Imaging LRL. Leonardo RodriguezCardiac Imaging

Key Result

In healthy subjects, the pooled lower limit of normal for two-dimensional right ventricular global longitudinal strain was -16.4%, establishing a reference threshold for abnormal strain.

Study Design

Type

Meta-Analysis (n=4,439)

Structured PICO

What are the normal reference ranges for right ventricular systolic strain by echocardiography in healthy subjects?

Population

45 studies pooling 4439 healthy subjects

Intervention

Two- (2D) and three-dimensional (3D) echocardiography for right ventricular global (RVGLS), free wall (RVFWLS) and interventricular septal wall (IVSLS) longitudinal strains

Outcome

Mean and lower limit of normal (LLN) of 2D and 3D RVGLS, RVFWLS, and IVSLSsurrogate

This meta-analysis establishes the pooled means and lower limits of normal for 2D and 3D right ventricular systolic strains in healthy subjects, providing thresholds for clinical use.

Limitations

Accuracy of RV systolic strain measurement may differ by subject and study depending on operator experience and image quality
Significant heterogeneity in the design, population, and methodology of strain measurements across studies
Not all clinical and echocardiographic characteristics were reported in all studies, limiting univariable meta-regression
Insufficient power for multivariable meta-regression
Lower limit of normal was defined arbitrarily as the boundary of the 95% CI rather than based on prognostic significance
Absence of patient-level data

Abstract

BACKGROUND: Right ventricular (RV) systolic strain has recently demonstrated prognostic value in various cardiovascular diseases. Despite this, the reference range including the lower limit of normal (LLN) and factors associated with RV strain measurements are not well-established. This meta-analysis aimed to determine the mean and LLN of two- (2D) and three-dimensional (3D) right ventricular global (RVGLS), free wall (RVFWLS) and interventricular septal wall (IVSLS) longitudinal strains in healthy individuals and factors that affect strain measurements. METHODS: In this meta-analysis, Pubmed, Embase and Cochrane databases were searched until 31 July 2020 for eligible studies reporting RVGLS, RVFWLS and/or IVSLS in at least 30 healthy subjects. We pooled the means and LLNs of RV strains by two- (2D) and three- (3D) dimensional echocardiography, and performed meta-regression analyses. RESULTS: From 788 articles screened, 45 eligible studies totaling 4439 healthy subjects were eligible for analysis. Pooled means and LLNs with 95% confidence intervals for 2D- RV strains were RVGLS -23.4% (-24.2%, -22.6%) and -16.4% (-17.3%, -15.5%) in 27 studies; RVFWLS -26.9% (-28.0%, -25.9%) and -18.0% (-19.2%, -16.9%) in 32 studies; and IVSLS -20.4% (-22.0%, -18.9%) and -11.5% (-13.6%, -9.6%) in 10 studies, and similar results for 3D- RV strains. Right ventricular fractional area change and vendor software were associated with 2D-RVGLS and RVFWLS means and LLNs. CONCLUSION: We reported the pooled means and LLNs of RV systolic strains in healthy subjects, to define thresholds for abnormal, borderline and normal strains. Important factors associated with RV systolic strains include right ventricular fractional area change and vendor software.

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