Global Longitudinal Strain Analysis of the Single Right Ventricle: Leveling the Playing Field

All available echocardiographic methods to assess single systemic right ventricular systolic function have limitations. Subjective grading is prone to bias and varies among readers. Quantitative methods that require significant manual input, such as fractional area change (FAC), are often not reproducible. The aim of this study was to determine whether global longitudinal strain (GLS) is more reproducible than FAC and subjective grading in patients with systemic right ventricle among individual readers and across different levels of experience.

Clinically indicated echocardiograms from 40 patients with functional systemic right ventricles were assessed by five readers with varying reading experience: one sonographer, one cardiology fellow, and three attending cardiologists at different career stages. All readers were blinded to patient data and other reader responses. Each reader reviewed the same images for subjective grade (on a scale ranging from 1 [normal] to 8 [severely depressed]), right ventricular end-diastolic and end-systolic area measurements, and longitudinal strain analysis. A repeat analysis was performed under identical conditions after ≥2 weeks on all 40 patients. Inter- and intrareader reproducibility was assessed using intraclass correlation coefficients (ICCs). Correlations between responses were assessed using Spearman's correlation coefficient.

The subjective method had fair to good reproducibility (ICC = 0.7; interquartile range [IQR], 0.60-0.72), while the FAC method was poor (ICC = 0.46; IQR, 0.39-0.51) among readers. Reproducibility for GLS was excellent (ICC = 0.88; IQR, 0.88-0.89). Intrareader reproducibility was excellent by subjective grading (ICC = 0.85; IQR, 0.73-0.88), poor by FAC (ICC = 0.63; IQR, 0.35-0.66), and excellent by GLS (ICC = 0.93; IQR, 0.88-0.96). Attending-level readers were more consistent with their subjective grading, while all readers were excellent with GLS.

GLS is more reproducible than conventional methods at assessing systemic right ventricular systolic function among readers with different levels of experience. For most readers it was more consistent than their own subjective grades of right ventricular function. Laboratories staffed by multiple readers are likely to be more consistent in grading systemic right ventricular systolic function using GLS.