P423Left atrial fibrosis predicts impaired atrial function: proof of concept
Bibliographic record
Abstract
Introduction: Left atrial (LA) remodeling, associated with changes in atrial geometry, function and texture, is the hallmark of the pathophysiology of atrial fibrillation (AF). Magnetic Resonance (MR) imaging plays a key role in the assessment of LA remodeling. Recently, fibrotic burden, longitudinal strain and sphericity are introduced as novel measures that can be used to characterize atrial remodeling. However, the relation between these parameters is yet unknown. This proof of concept study evaluated the association between LA longitudinal strain measured by MR Tissue Tracking, LA sphericity, and LA fibrotic burden in paroxysmal AF patients referred for catheter ablation. Method: Eight paroxysmal AF patients underwent MR imaging (1.5T Avanto, Siemens) in sinus rhythm prior to their pulmonary vein isolation (PVI) procedure. Sphericity and fibrotic burden were assessed from 3D wholeheart and late gadolinium enhancement (LGE) images acquired at the end of atrial diastole, using custom-written software. LA longitudinal strain was derived from cine-MR images using Tissue Tracking (Circle CVI42, Calgary, Canada). Corresponding to the 3 LA phases, strain measurements were subdivided into total strain (representing atrial reservoir function), passive strain (representing LA conduit function) and active strain (representing LA contractile booster pump function). The LA longitudinal strain was compared to sphericity and fibrotic burden in AF patients. Results: Mean LA sphericity was 70.69 ± 2.16% and mean LA scar burden was 13.29 ± 15.44%. Total LA strain and passive LA strain had a strong correlation with scar burden (R2 = 0.63; p = 0.019, R2 = 0.88; p = 0.001, respectively) (figure 1A and 1B). Active strain, representing atrial booster function, was not correlated with LA fibrotic burden (R2 = 0.1; p = 0.455) (figure 1C). LA scar area had no correlation with LA sphericity (R2 = 0.13; p = 0.382) (figure 1D). No relation was observed between LA sphericity and longitudinal strain. Conclusion: LA reservoir function and LA conduit function are both significantly impaired in the presence of LA scar, while active atrial booster function was not affected. Therefore, impaired passive atrial deformation may serve as an early indicator of atrial fibrosis, even in the presence of limited remodeled atria, as indicated by a preserved, non-spherical shape. Future studies with a larger patient cohort are warranted to explore this concept in more detail. Abstract P423 Figure.
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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 | 0.011 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".