Comparison of Quantitative Versus Qualitative Assessment of Single Right Ventricular Function for the Prediction of Midterm Outcomes

Relationship Between Obesity and Global Longitudinal Strain in the Pediatric Single Ventricle Fontan Population Across Ventricular Morphologies

BACKGROUND

Obesity is associated with diminished myocardial function as measured by strain echocardiography in children and young adults with normal cardiac anatomy. Data are lacking about the effect of obesity on myocardial strain in patients with a single ventricle. In this study, the relationship between body mass index (BMI) and single ventricle myocardial strain in the Fontan population was assessed.

METHODS AND RESULTS

Thirty-eight abnormal BMI Fontan cases (21 overweight and 17 obese) and 30 normal BMI Fontan controls matched based on single ventricular morphology, age, and sex were included in the study. Ventricular morphology was categorized as single right ventricle, single left ventricle, or biventricular. Single ventricle global longitudinal peak systolic strain (GLS) and other echocardiographic measurements were performed and compared between groups, with a P≤0.05 defined as significant. The abnormal BMI group demonstrated diminished GLS (-15.7±3.6% versus -17.2±3.2%, [P=0.03]) and elevated systolic blood pressure (P=0.04) compared with the normal BMI group. On subgroup analysis of those with single right ventricle morphology, the abnormal BMI group demonstrated diminished GLS compared with controls. There was no significant difference in GLS between the abnormal BMI and control groups in the single left ventricle and biventricular subgroups. Analyzed by ventricular morphology, no other variables were statistically different in the abnormal BMI group including systolic blood pressure. Inter-reader reproducibility for GLS and strain rate were excellent for both measures.

CONCLUSIONS

Obesity has an adverse relationship with myocardial strain in the young Fontan population, with the most maladaptive response seen in the single right ventricle.

Global longitudinal strain analysis of the singe right ventricle: leveling the playing field

BACKGROUND

All available echocardiographic methods to assess single, systemic right ventricle (sRV) 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 is to determine whether global longitudinal strain (GLS) is more reproducible than FAC and subjective grading in sRV patients among individual readers and across different levels of experience.

METHODS

Clinically indicated echocardiograms for 40 patients with functional systemic right ventricles were assessed by 5 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 (scale 1-8, normal to severely depressed), RV end-diastolic and end-systolic area measurements, and longitudinal strain analysis. A repeat analysis was performed under identical conditions after at least 2 weeks on all 40 patients. Inter- and intra-reader reproducibility was assessed with intraclass correlation coefficient (ICC). Correlations between responses were assessed with Spearman's correlation coefficient.

RESULTS

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) between readers. Reproducibility for GLS was excellent (ICC 0.88, IQR 0.88,0.89). Intra-reader 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.

CONCLUSION

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