Can Right Ventricular Lead Position Influence Paced QRS Duration in Patients with Abnormal and Normal Left Ventricular Function?
Bibliographic record
Abstract
Right ventricular apical pacing (RVAP) in pacemaker or implantable cardioverter‐defibrillator (ICD) therapy has been associated with the development and exacerbation of heart failure (HF). Studies have suggested that RVAP resulting in dyssynchronous left ventricular (LV) activation and prolonged QRS duration leads to progressive mechanical dysfunction, decreased systolic function and increased mortality. These data suggest that the effect may be most pronounced in patients with pre‐existing LV systolic dysfunction. Pacing at the RV septum however has demonstrated narrower paced QRS durations and is being considered as an alternative pacing site to the RVA. In this study, the effect of RV lead placement on the QRS duration in patients with LV systolic dysfunction who demonstrate a left ventricular ejection fraction (LVEF) < 35% and normal LVEF was compared. Patients of a minimum age of 18 years with LVEF ≥ 50% (normal cohort) and LVEF ≤ 30% (HF cohort) were recruited. Four 3 minute high resolution recordings were obtained from an orthogonal lead position for subsequent offline signal averaging. Recordings of native rhythm and pacing at three RV sites: right ventricular outflow tract (RVOT), mid‐septum and RV apex (RVA) were obtained. A 12‐lead electrocardiogram (ECG) recording at each pacing site was stored for later confirmation of pacing location and comparison with paced averaged QRS duration. The QRS duration at different RV sites in the two populations was then compared. As studies to date are limited, this study provided valuable insight on RV lead placement on QRS duration in device therapy for HF treatment.
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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 | 0.004 |
| 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 | 0.001 | 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".