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

BACKGROUND: 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. METHODS: 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. 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) 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. CONCLUSIONS: 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.

Single systemic right ventricle longitudinal strain: Intravendor reproducibility and intervendor agreement in children.

PURPOSE: Strain derived from speckle-tracking echocardiography is emerging as a useful tool in the assessment of single ventricle function. The purpose of this study is to compare layer-specific longitudinal strain values in children with single, systemic right ventricles (sRV) using two commercially available software platforms (GE EchoPAC (EP) and TomTec (TT)). METHODS: Two readers analyzed two-dimensional longitudinal strain on EP (v 202) and TT (v 2.21.25) in 40 pediatric sRV patients. Intravendor reproducibility and intervendor agreement between layer-specific measurements were assessed by intraclass correlation coefficient and Bland-Altman analysis. Absolute difference (AbΔ) and relative mean errors (RME) were calculated. Subgroup comparisons (stratified by age, heart rate (HR), and frames per second (FPS): HR ratio) were made. RESULTS: Median age was 4.4 years. 32 (80%) patients had hypoplastic left heart syndrome; 19 (48%) were post-Fontan. Intravendor reproducibility was excellent with high ICC (0.86-0.97). AbΔ between readers was small (1.2%-1.5%) with interobserver RME slightly higher for TT (11%-12% vs 8%-9% for EP). Layer-specific intervendor agreement was poor (ICC 0.45-0.62). Default layer comparisons (EP mid vs TT endo) showed good agreement (ICC 0.72-0.77) and less variability (AbΔ 2%, RME 15%) than layer-to-layer. There were no differences in ICC for groups dichotomized by age, HR, or FPS:HR ratio. sRV strain values are more negative when using EP. CONCLUSION: Intravendor reproducibility for sRV peak longitudinal strain in children is excellent with acceptable variability between experienced users. Intervendor, layer-specific strain agreement is poor. Vendor default layer strain values show better agreement but are not interchangeable.

Assessing the atria in pediatric sickle cell disease: Beyond the dilation.

BACKGROUND: Diastolic dysfunction (DD) and pulmonary hypertension (PH) are common causes of mortality for sickle cell disease (SCD) patients in developed countries. We hypothesized that left and right atrial strain (LAS-Ɛ, RAS-rƐ) are decreased in SCD adolescents, and that worsening values correlate with laboratory markers of disease severity. METHODS: Prospective cohort study of patients with HbSS genotype of SCD was compared with healthy controls. LAS and RAS were measured from 4- and 2-chamber views by a blinded reader. Peak strain and strain rate values were obtained for atrial contraction (ac), reservoir (res), and conduit (con) phases. Mitral/tricuspid Doppler velocities, left atrial volume, right atrial area were obtained. Laboratory variables were obtained from the electronic record with the three prior values being averaged. Differences in variables were assessed with Wilcoxon rank sum test, and correlations assessed with Spearman's coefficient. RESULTS: There were 33 SCD patients compared to 35 healthy controls of similar age, gender, and size. SCD patients had increased left atrial volume and right atrial area. For LAS, Ɛres was significantly lower in SCD patients. For RAS, RƐcon was significantly lower. Neither measurement correlated with clinical markers. The majority of SCD patients had relatively normal atrial strain values. Those with markedly lower values had similar atrial size. CONCLUSIONS: A sub-set of SCD patients have markedly low Ɛres and rƐcon. No correlation with clinical markers was identified. Larger, longitudinal studies may determine utility of atrial strain as a screening tool in this at-risk population.

Assessing the left atrium of childhood cancer survivors.

Survivors of childhood cancer are at risk of cancer therapy-related cardiac dysfunction (CTRCD) characterized by systolic impairment, with little known about diastolic function. Left atrial strain (LAS) is a surrogate measure of left ventricular filling. We hypothesized that survivors (1) have lower LAS versus controls, and (2) survivors exposed to higher anthracycline dosage have even lower LAS. Cross-sectional study of 45 survivors exposed to anthracyclines ≥ 1 year after chemotherapy and 45 healthy controls. Echo variables included mitral spectral and tissue Doppler, left ventricular ejection fraction (LV EF), LV dimension, LA volume, LV global longitudinal strain (GLS), and LAS. Peak strain (Ɛ) and strain rate (SR) at three phases were obtained: atrial contraction (ac), reservoir (res), and conduit (con). Two sub-analyses of cancer survivors were performed: (1) those with anthracycline dosage ≥ 250 mg/m2, and (2) those with Ɛres in the lowest quartile. On the whole, survivors had lower Ɛres and Ɛcon values. The majority of survivors had relatively normal LAS, while a subset had very low LAS values and were more likely to be older. Survivors exposed to ≥ 250 mg/m2 anthracycline also had lower Ɛres than those < 250 mg/m2. There were no differences in mitral spectral/tissue Doppler, LV dimension, left atrial volume, or GLS. A subset of childhood cancer survivors have lower LAS than their healthy counterparts, while most are essentially normal. Those exposed to higher anthracycline dosage have even lower Ɛres. Longitudinal study of LAS may prove useful in monitoring for CTRCD.