Evaluation of a non-invasive right ventriculo-arterial coupling parameter in repaired tetralogy of Fallot by cardiovascular magnetic resonance imaging and correlation with exercise testing
Bibliographic record
Abstract
Abstract Background and purpose Invasively measured right ventricle (RV) to pulmonary arterial coupling (RVPAc) quantifies RV performance within the context of its afterload but requires cardiac catheterization thereby limiting widespread use. We sought to compare a volumetric non-invasive RVPAc parameter in a contemporary cohort of children and adults with repaired tetralogy of Fallot (rToF), to investigate the impact of pulmonary regurgitation (PR) and RV outflow tract obstruction (RVOTO), and to correlate RVPAc with exercise capacity. Methods We retrospectively compared 99 pediatric and 117 adult patients with rToF who had performed cardiovascular magnetic resonance imaging (CMR) and exercise testing (CPET) within 1 year. Sanz’s method was used to non-invasively calculate RV-PA coupling as the ratio of RV end-systolic volume over stroke volume (ESV/SV); where a ratio >1 is considered ‘uncoupled’ [1]. Right-ventricular outflow tract gradient was obtained by echocardiography; PR fraction and Nakata-index [2], to quantify PA size, were calculated by CMR. We also calculated ‘effective SV’ by subtracting regurgitant volume from RV SV; which allowed for calculation of ‘effective’ RVPAc. Exercise capacity was measured as percentage of predicted peak oxygen consumption (%VO2) during cardio-pulmonary exercise testing. Subgroups were established depending on PR-RVOTO combination (cut-off defined as PR >30% and RVOTO > 25mmHg). Results RVPAc was significantly higher in the adult group [1.24 (1.03-1.49) vs. 1.00 (0.88-1.15); p<0.001]. According to PR-RVOTO, RVPAc was overall comparable between pediatric and adult cohorts (respectively p=0.379 and 0.053). RVPAc highly correlated with RV ejection fraction (RVEF) (r=-0.991, p<0.001), moderately correlated with indexed RV ESV (r= 0.696, p<0.001) and QRS duration (0.598, p<0.001), and weakly correlated with indexed RV end-diastolic volume (RVEDVi) (r=0.351, p<0.001), indexed RV SV (r= -0.241, p<0.001), LV ejection fraction (LVEF)(r= -0.382, p<0.001) and Nakata-index (r=0.264, p=0.002). There was no significant association between RVPAc and RV outflow tract gradient (p=0.109) or pulmonary regurgitant fraction (p=0.411). RVPAc was not significantly correlated with %VO2 (p=0.294). This remained true for subgroup analysis in the pediatric and adult cohorts separately. Regression models, which included age, BSA and either RVEF, RVPAc or ‘effective RVPAc’ to predict exercise capacity (%VO2) demonstrated an overall poor fit (adjusted R2 0.170; 0.176 and 0.181 respectively). Conclusion Adults with rToF have higher RVPAc ratio than pediatric patients which could signify progressive RV-PA ‘uncoupling’ with age or era-related pathological effects. Non-invasive RVPAc correlates with RVEF, RV volumes, PA size, LVEF and QRS duration, which could be used to track progressive RV dysfunction. Nonetheless, its clinical use appears limited as it does not predict exercise capacity better than RVEF.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".