Effect of change in posture and exercise on repolarization in patients with long QT syndrome with HERG channel mutations.
Bibliographic record
Abstract
INTRODUCTION: Congenital long QT syndrome (LQTS) is characterized by syncope and cardiac arrest, often in association with exercise or sudden arousal. It was hypothesized that patients with LQTS with human ether-a-go-go-related gene (HERG) mutations (LQT2) have an abnormal QT adaptation to changes in heart rate induced by exercise and that such abnormalities may be ameliorated by treatment with beta-adrenoreceptor blockers. METHODS AND RESULTS: Sixteen LQT2 patients (26+/-15 years of age, 10 female) and 27 healthy volunteers (34+/-16 years of age, 17 female) had 12-lead electrocardiograms recorded while supine, immediately on standing and continuously during treadmill exercise testing. Changing from supine to standing alone caused a significant increase in QTc in the LQT2 group compared with in control subjects (change in QTc of 48+/-38 ms versus 21+/-29 ms, respectively, P=0.02). While QT and QTc remained longer in LQT2 patients at peak exercise, QT shortening (QT peak minus QT supine) was greater in LQT2 patients than in control subjects (-158+/-32 ms versus -117+/-32 ms, P<0.001). Beta-blocker treatment had no effect on the resting QTc, but it normalized the increase in QTc on standing (45+/-29 ms before beta-blocker versus 23+/-32 ms after beta-blocker, P=0.03). During exercise, QT shortening and peak QTc were not affected by beta-blocker treatment. CONCLUSIONS: Abnormal repolarization in LQT2 is accentuated by a change in posture and exercise. Beta-blockers normalize the QTc prolongation elicited by such manoeuvres.
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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 | 0.001 |
| 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) | 0.001 | 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".