Effect of Simvastatin and Antioxidant Vitamins on Atrial Fibrillation Promotion by Atrial-Tachycardia Remodeling in Dogs
Bibliographic record
Abstract
BACKGROUND: There is evidence for a role of oxidant stress and inflammation in atrial fibrillation (AF). Statins have both antioxidant and antiinflammatory properties. We compared the effects of simvastatin with those of antioxidant vitamins on AF promotion by atrial tachycardia in dogs. METHODS AND RESULTS: We studied dogs subjected to atrial tachypacing (ATP) at 400 bpm in the absence and presence of treatment with simvastatin, vitamin C, and combined vitamins C and E. Serial closed-chest electrophysiological studies were performed in each dog at baseline and 2, 4, and 7 days after tachypacing onset. Atrioventricular block was performed to control ventricular rate. Mean duration of induced AF was increased from 42+/-18 to 1079+/-341 seconds at terminal open-chest study after tachypacing alone (P<0.01), and atrial effective refractory period (ERP) at a cycle length of 300 ms was decreased from 117+/-5 to 76+/-6 ms (P<0.01). Tachypacing-induced ERP shortening and AF promotion were unaffected by vitamin C or vitamins C and E; however, simvastatin suppressed tachypacing-induced remodeling effects significantly, with AF duration and ERP averaging 41+/-15 seconds and 103+/-4 ms, respectively, after tachypacing with simvastatin therapy. Tachypacing downregulated L-type Ca2+-channel alpha-subunit expression (Western blot), an effect that was unaltered by antioxidant vitamins but greatly attenuated by simvastatin. CONCLUSIONS: Simvastatin attenuates AF promotion by atrial tachycardia in dogs, an effect not shared by antioxidant vitamins, and constitutes a potentially interesting new pharmacological approach to preventing the consequences of atrial tachycardia remodeling.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".