Left ventricular extracellular volume is associated with loss of exercise tolerance in children after Tetralogy of Fallot repair, but not with ventricular dysfunction
Bibliographic record
Abstract
Diffuse myocardial fibrosis is associated with heart failure and ventricular dysfunction in many diseases. The aim of this study was to relate cardiac magnetic resonance (CMR) measures of diffuse myocardial fibrosis to cardiomechanics and exercise tolerance. In 25 patients (age 13.6±2.5 years, 14 male) after surgical repair of Tetralogy of Fallot (ToF), T1 measurements were performed at a mid and basal ventricular level in short axis before and 15 minutes after the application of 0.1 mmol/kg gadobenate dimeglumine in the interventricular septum (IVS), left ventricular (LV) lateral wall, complete LV myocardium and diaphragmatic portion of the right ventricle (RV). The extracellular volume (ECV) was calculated from native and post-contrast T1 times of myocardium and blood and the hematocrit. Peak circumferential (LV), longitudinal (RV) and radial (RV) strain as well as the standard deviation of the time to peak strain of different segments (SDpeak) were measured using CMR feature tracking. The correlation of native T1 times and ECV with strain parameters was tested using Pearson's coefficient. Native T1 times and ECV were correlated to exercise test results. The mean pulmonary regurgitation fraction was 36±16% and RV enddiastolic volumes were enlarged (EV-EDV 155±52 ml/m ) with near-normal ejection fraction (RV-EF 47±8%). LV measures were unremarkable. (Native T1 times and ECV did not differ significantly between different parts of the LV (native T1 time: IVS 1001±52 ms, LV lateral wall 978±55ms, entire LV 982±39ms; ECV: IVS 25±4%, LV lateral wall 23±5%, entire LV 24±3%) and between males and females, but were higher in the RV as compared to the LV (RV native T1 times 1021±69ms (vs. entire LV p<0.05), ECV 29±6% (vs. entire LV p<0.005)). There was no correlation of LV or RV native T1 times and ECV with peak segmental and global strain (global LV peak circumferential strain -22.2±4.6%, RV radial and longitudinal strain of the RV free wall 28.6±18.8% and -11.5±5%) nor with SDpeak (LV 49±30ms or 6.4±3.8% of RR-interval). Exercise test results, available in 11 patients, correlated negatively with ECV of the entire LV (V02 max. r=-0.62, p<0.05, Peak workload r=-0.63, p<0.05). In patients after ToF repair, CMR measures of diffuse myocardial fibrosis are associated with exercise intolerance but not with LV or RV dysfunction.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".