686Automatic AVD Programming by SyncAV Improves Electrical Synchronization in a Multicenter Study of CRT Patients
Bibliographic record
Abstract
Introduction: SyncAV, a new CRT feature that continually programs atrioventricular delay (AVD) shorter than the intrinsic AV conduction time (by a default or programmable offset), may improve electrical synchrony by fusion of intrinsic, LV-paced, and RV-paced activation wavefronts. However, it is not known how the degree of synchronization achieved depends on the LV pacing vector selected. Objective: Evaluate the electrical benefit of SyncAV by late- vs. early-activated LV pacing vectors. Methods: Ninety patients (74% male, 44% ischemic, 62% LBBB, 32±9% ejection fraction) post-CRT implant (23±28 months) using a quadripolar lead (Quartet™, Abbott) were enrolled prospectively. QRS durations (QRSd) were measured by a blinded observer from 12-lead ECG during: intrinsic conduction, biventricular pacing (BiV) + SyncAV™ OFF (sensed/paced AVD = 140/110 ms), BiV + SyncAV™ ON (nominal 50 ms offset), BiV + SyncAV™ ON (offset optimized to minimize QRSd), RV-only pacing, and LV-only pacing + SyncAV™ ON (nominal 50 ms offset). Each BiV pacing configuration used simultaneous V-V and was compared using the LV electrode along a quadripolar lead with the latest (BiVLateLV) vs. earliest (BiVEarlyLV) during RV pacing. Results: Conduction delay from RV pacing to LV sensing was significantly longer at the BiVLateLV cathode than the BiVEarlyLV cathode (174±29 vs. 154±32 ms, p<0.001). The QRSd associated with intrinsic conduction (155±29 ms) was narrowed with BiVLateLV + SyncAV OFF to 138±27 ms (9±20% reduction, p<0.001). Further QRSd narrowing to 133±25 ms (13±14% reduction, p<0.05 vs. BiV + SyncAV OFF) was achieved by BiVLateLV + SyncAV ON (nominal offset). The greatest QRSd narrowing to 123±22 ms (20±10% reduction, p<0.001 vs. BiV + SyncAV ON (nominal offset)) was achieved by BiVLateLV + SyncAV ON (optimized offset). However, there was no statistical difference between the QRSd narrowing achieved by BiVLateLV vs. BiVEarlyLV using either SyncAV offset (p=0.4-0.9). The optimal SyncAV offsets resulted in an AVD of 81.1±9.4% of the intrinsic AV interval, much longer than what is usually programmed with other optimizing methods. Expectedly, RV-only pacing actually prolonged QRSd by 10±18% relative to intrinsic conduction, and although LV-only pacing + SyncAV ON (nominal offset) narrowed QRSd by 8±16%, the reduction was no greater than BiV + SyncAV OFF with either BiVLateLV or BiVEarlyLV. Conclusion: SyncAV improves acute electrical synchrony beyond conventional CRT, particularly with patient-specific optimization, but is unaffected by the choice of LV pacing vector along a quadripolar lead (i.e., late- or early-activated). Abstract 686 Figure.
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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 | 0.001 |
| 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) | 0.000 | 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".