Dynamic Nature of Atrial Fibrillation Substrate During Development and Reversal of Heart Failure in Dogs
Bibliographic record
Abstract
BACKGROUND: Clinical atrial fibrillation (AF) often results from pathologies that cause atrial structural remodeling. The reversibility of arrhythmogenic structural remodeling on removal of the underlying stimulus has not been studied systematically. METHODS AND RESULTS: Chronically instrumented dogs were subjected to 4 to 6 weeks of ventricular tachypacing (VTP; 220 to 240 bpm) to induce congestive heart failure (CHF), followed by a 5-week recovery period leading to hemodynamic normalization at 5-week recovery (Wk5(rec)). The duration of burst pacing-induced AF under ketamine/diazepam/isoflurane anesthesia increased progressively during VTP and recovered toward baseline during the recovery period, paralleling changes in atrial dimensions. However, even at full recovery, sustained AF could still be induced under relatively vagotonic morphine/chloralose anesthesia. Wk5(rec) dogs showed no recovery of CHF-induced atrial fibrosis (3.1+/-0.3% for controls versus 10.7+/-1.0% for CHF and 12.0+/-0.8% for Wk5(rec) dogs) or local conduction abnormalities (conduction heterogeneity index 1.8+/-0.1 in controls versus 2.3+/-0.1 in CHF and 2.2+/-0.2 in Wk5(rec) dogs). One week of atrial tachypacing failed to affect the right atrial effective refractory period significantly in CHF dogs but caused highly significant effective refractory period reductions and atrial vulnerability increases in Wk5(rec) dogs. CONCLUSIONS: Reversal of CHF is followed by normalized atrial function and decreased duration of AF; however, fibrosis and conduction abnormalities are not reversible, and a substrate that can support prolonged AF remains. Early intervention to prevent fixed structural abnormalities may be important in patients with conditions that predispose to the arrhythmia.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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".